Cast Iron heads for 300TDi?

[Tank]

Does such a beast exist, any info would be welcome, that and a Cam Chain drive would be the perfect engine, surely someone somewhere has thought about this, Regards Frank.

[Casper]

That would be great but having the possibility of running common rail would make it even better, more power and economy for those not so worried about electrics.

The cam chain would be relatively easy thing to do, you can get sprockets made to measure and run a standard chain like off a Falcon 6 or even a holden but the problem would still be in the stretch.

Cam chains still stretch and they wear sprockets, this is why most industrial and commercial diesels run timing gears not belts or chains.

The other thing is noise, chain can be shut up with fibrous sprocket on the drive but again that gives a weak point and gears can be shut up with helical cutting and oiling which the 300Tdi timing case and Cam and Pump would not be able to take the forces as they are not designed to do so.

You could probably redesign it etc with a cast iron cover with bearing cones built in to remove the side forces from the gears to the case but it would add a huge amount of weight and bulk to the engine that I don't think it would be worth it.

The cast iron head though would be a great but again the weight difference might negate any advantage other than service life.

Cheers Casper

[uninformed]

Hi Frank. I have never heard of a cast iron head for a tdi. Maybe there is one :confused:. Lets look at why the alloy head fails:

EGTs get to high.
Engine temp get to high
poor servicing.
Head gasket failure.

IMO the alloy head is probably fine, especially the newer ones. Fitting a new cast iron head will not address the EGT's or the engine cooling. It comes down to being under intercooled and undercooled. Having a defender temp gauge is certainly no help either. IMO if a bigger radiator and intercooler were fitted, a better free flowing exhaust. Alot of head problems would be less. I think the newer head gaskets may also be better.

There is a better timing belt available from the UK. It is the one for the 2.8tgv, it is the same length and tooth profile, but a stronger belt. International have there scheduled timing belt change at 120k. The timing gears on the 2.8tgv are alot stronger also.....maybe these fit a 300tdi.

just my thoughts and all could be wrong

[wagoo]

If a local company like Yella Terra could justify casting replacement cylinder heads for the the old Holden red,blue and black 6 cylinder engines, surely some enterprising concern could see the higher volume global sales potential for a cast iron replacement for the 200/300 tdi.
Bill.

[rick130]

If you are going to fit an iron head to a Tdi you may as well just drop in a 4BD1T.

The iron head definitely resists a major overheat better, we've cooked our Patrol TD42T twice now, once that would have absolutely destroyed a Tdi and it's still soldiering on as good as new at near 400,000km (touch wood :angel:) without a spanner on the engine.

[rangieman]

I have often thought of this and one thing that springs to mind is i thought the Tdi was based on the old style rover 2,25 come 2,5 engines s , If so would a head off one of these old engines fit , Surely someone has one lying around that could be dry fitted :cool:

[Tank]

I have often thought of this and one thing that springs to mind is i thought the Tdi was based on the old style rover 2,25 come 2,5 engines s , If so would a head off one of these old engines fit , Surely someone has one lying around that could be dry fitted :cool:
I have a couple (heads 2.25) laying about, but even if they could be fitted the 2.25 heads are pre-combustion (indirect injection) chamber heads and I imagine that there would not be the same HP produced by these old type heads. I have sent some emails to some Chinese suppliers of heads whether they could cast a few of their alloy 300tdi heads in cast iron, will let you know the results, Regards Frank.

[rick130]

I have sent some emails to some Chinese suppliers of heads whether they could cast a few of their alloy 300tdi heads in cast iron, will let you know the results, Regards Frank.

Now that'd be interesting Frank.

[Jeff]

The reason the TDi went to a timing belt instead of a chain is because a previous Rover engine the 2.25 had a cam chain. It was not normally a problem in Land Rovers, but the same engine was used in black cabs and prolonged idling caused oil pressure related problems, as the oil pressure driven cam chain tensioner would not operate properly at idle. Engine problems ensued and Rover went to a belt as it was not only not dependant on oil pressure, it was quieter.

Early in the TDi's life, a company called Zeus made a gear driven timing conversion, but the hardening on the gears was not always good and you don't see them mentioned these days.

Jeff

:rocket:

[uninformed]

Hi Jeff, I have heard from someone that fitted the odd Zeus gear set. From his reports the main problem was the extreme helic angle that the gears were cut on, and that they are only supported from one side. The thrust pressure would be alot due to this. He did say that the casting of the front cover and the gears themselves seemed beautifuly made. Just some poor design that let them down. Unfortunately they have been hit and miss. Some people have had great service from them, others have had total engine failure due to them. They are not cheap, and the risk involved seems to high to me.

I think Turners had a big stoush with Zues :confused: as they were fitting them and problems acured......but that is my vague memory and could be way off :confused:

[wagoo]

The reason the TDi went to a timing belt instead of a chain is because a previous Rover engine the 2.25 had a cam chain. It was not normally a problem in Land Rovers, but the same engine was used in black cabs and prolonged idling caused oil pressure related problems, as the oil pressure driven cam chain tensioner would not operate properly at idle. Engine problems ensued and Rover went to a belt as it was not only not dependant on oil pressure, it was quieter.


Jeff

:rocket:
I'm not sure I understand how the variable oil pressue would cause problems with the chain tensioner.The tensioner mechanism has a ratchet device so that tension is maintained when oil pressure drops as when engine is shut down. This works very reliably on 2.25 petrol engines. Perhaps the cam/injection timing of the deisel is more sensitive to chain stretch or when there is some lash in the chain, but not quite enough for the tensioner mechanism to adjust to the next tooth on the ratchet.In which case a finer toothed ratchet may have been a solution.

I believe the universally highly respected Gardiner deisel engines had chain driven timing gears.
Bill.

[Dougal]

That would be great but having the possibility of running common rail would make it even better, more power and economy for those not so worried about electrics.

Commonrail doesn't have any significant power or economy benefits over mechanical direct injection, but it can burn a lot cleaner and quieter with pilot injection.

Nissan use timing chains and hydraulic tensioners on most of their engines, some of them (like the LD28) have a habit of jumping a tooth if revved when the engine is cold and oil pressure is low. These aren't ratchet tensioners, just spring backed with oil pressure.

Precombustion chamber diesels (indirect injection) are a major step backwards in power, efficiency and head-strength.

[PAT303]

Funny how alloy headed Tdi's overheat and fail because people won't spend money to fix them properly but then have no problem spending alot more for a cast iron head that will somehow by a miracle won't have a problem with overheating just because they are cast iron???. Pat

[rick130]

Funny how alloy headed Tdi's overheat and fail because people won't spend money to fix them properly but then have no problem spending alot more for a cast iron head that will somehow by a miracle won't have a problem with overheating just because they are cast iron???. Pat

:confused:

[manic]

someone just recast the the older heads.. do it now! alloy or iron there's owners out there would give a boolok for a new one.... Who's moaning about there not being a 300tdi iron option!? If your head fails cos you poked it -> just get a brand new one and count yourself lucky... my 200tdi is on scraps! :p

[Tank]

Copy of an email (at bottom) I sent to Turners asking if there was anyone making a cast iron head for the 300TDi and their reply. I also sent an email to a Chinese company and they are going to make enquiries and get back to me during the week coming, Regards Frank.

Dear Frank
I am afraid there is no such thing as a cast iron cylinder head for the
300TDI.

Provided the 300TDI engine cooling system is kept in good order and the fuel
injection equipment serviced on time, Ie combustion conditions are good the
head gasket/cylinder head should not be giving any problems. We supply both
south American and the Spanish replacement cylinder heads and under good
operating conditions they will not give trouble. We also use the composite
original Elring head gasket rather than the mls later type

Reference cast iron, this type of head was fitted to the 2.5TD engine in the
80's and we were selling just as many of those as we are for the 300TDI if
not more due to cracking of the cylinder head caswtings due
overheating/faulty injection equipment. The same principal applies, for a
head gasket/cylinder head to last good operating conditions are required.

Often the radiator is a culprit with the 300tdi as it relatively small and
when partially blocked will cause problems with the engine.

I trust the above explains and should you require a new cylinder head
assembly this is available direct from our online store here.
http://www.turnerengineering.co.uk/acatalog/300Tdi.html (wlmailhtml:{0E55BC53-D98B-4177-869A-6304B33F059E}mid://00000004/!x-usc:http://www.turnerengineering.co.uk/acatalog/300Tdi.html)
Regards
Frida Turner
Turner Engineering
Churchill House, West Park Road, Newchapel, nr Lingfield, Surrey RH7 6HT,
United Kingdom
n Tel : +44 (0) 1342 834713
T Fax: +44 (0) 1342 834042
www.turner-engineering.co.uk (wlmailhtml:{0E55BC53-D98B-4177-869A-6304B33F059E}mid://00000004/!x-usc:http://www.turner-engineering.co.uk/)
www.turnerengineering.co.uk (wlmailhtml:{0E55BC53-D98B-4177-869A-6304B33F059E}mid://00000004/!x-usc:http://www.turnerengineering.co.uk/)

Division of Agency & General Investment Co Ltd
Registered in England No: 1115015 - Registered Office : BR1 3RA
VAT registration No: GB 210 9301 15

-----Original Message-----
From: sales@turner-engineering.co.uk (wlmailhtml:{0E55BC53-D98B-4177-869A-6304B33F059E}mid://00000004/!x-usc:mailto:sales@turner-engineering.co.uk) [mailto:sales@turner-engineering.co.uk]

Sent: 25 February 2012 05:13
To: sales@turner-engineering.co.uk (wlmailhtml:{0E55BC53-D98B-4177-869A-6304B33F059E}mid://00000004/!x-usc:mailto:sales@turner-engineering.co.uk)
Subject: Cast Iron 300 TDi cylinder head

Name:Frank Stanton
Email Address:Frank.Stanton@bigpond.com
Message:
Is there a cast iron cylinder head for a 300TDi, it seems to be a major
problem with this motor, especially here in Australia.
Most alloy 300 TDi heads seem to give up the ghost between 250,000klms and
300,000klms. Given the vast distances travelled in outback Australia a cast
iron head would give more confidence and reliability then the alloy heads.
With the Chinese copying everything nowdays at a good price maybe some bare
heads could be bought and machined by you. There would be a tremendous
market in Australia for a more reliable head for the 300TDi, Regards Frank.

[rick130]

Thanks Frank, Frida's comments makes sense, and we all recognise the radiator is marginal in capacity.

I wonder which head Turners reckon is better ?
The Brazilian or Spanish version ?

[Dougal]

It's not a good comparison saying that the idi 2.5td cast iron heads also cracked. IDI heads are weaker due to the large hole that is the pre-combustion chamber pocket and take more load due to the higher compression ratio.

Isuzu has a great example, the Isuzu 4BD1T is a 3.9l direct injection turbo engine with cast iron head. Head failures are rarer than bigfoot sightings.
The Isuzu 4BD2T engine is exactly the same block but indirect injection with a cast iron head fitting precombustion chambers and slightly higher compression ratio (about 2 points).
The 4BD2T cracks heads often enough that replacements are all over ebay.

[wagoo]

Re Turner Engineerings reply. Whilst they obviously have an excellant reputation for engine reconditioning, they are probably not known for innovation.With the exception of Ashcrofts,if it was left to British industry to develop upgrades for Landrovers we'd be still stuck with 10 spline halfshafts and 2 pinion non locking differentials. And that is coming from a Pom.
Tank, send your enquiry to the manufacturers of Yella Terra heads.
Bill.

[uninformed]

As with what Turner's said, I'd add:

uping the boost (gasket cant cope)
uping the fuel (EGT's and engine temps rise, head cant cope)

How much is a new head going to cost? If you go to the trouble of setting up a full width intercooler and a almost full width Rad, that could help long term....yes you have to replace Rads eventually, but if you not changing the cause of the problem, just the result, you will have to replace that again also.

[Tank]

Thanks all for your informative input, I agree that the Radiatior is too small for the job, I had extra tubes fitted to my new one. I still think alloy heads on turbo diesels will have the problems.
I have fitted 2 composite head gaskets and 1 shim metal one in the time I have had tis 300TDi, in the first case the head had warped (380,000klm) 7 thou., I had it machined and the valves reseated.
A few months later the headgasket let go again (in almost the exact same spot on Clyde Mountain on the Kings Hwy.), another composite and new head bolts, the head had warped 7 thou again between cyls. 2 and 3.
On the last occasion I fitted the 3 layer metal gasket, but did not machine the head again. So far (about a year, knock on wood) all seems well, at no stage did the head gasket blow due to overheating, the first sympton of a blown head gasket was pressurising the header tank and later overheating. The warping was in the same position as previously, an area about75mm+ circle covering about half of #2 and #3 combustion areas, so there is a 3 to 4" depression directly in the middle of the head, probably gone soft.
I have worked on and off for around 30 years on mine and others trucks and I have never seen this on a cast iron head, so if I can get a cast iron head for my 300TDi I would be happy, if not I will get a new alloy head a shim metal head gasket and a set of ARP head studs, Regards Frank.

[Dougal]

Just to let you know about another 2.5 diesel I own with similar issues.

Nissan YD25 which has a steel block and alloy head. These also do head-gaskets for similar reasons. The turbo is water-cooled and these water lines corrode first developing pin-hole leaks near the turbo. The resulting water loss is slow enough that it isn't noticed until the head-gasket goes.

The van I bought with this problem had already had the gasket done by the previous owners, but the muppets (truck workshop) hadn't cleaned the block so the new gasket wasn't any better.
I had the van up for sale, the gasket went when I was delivering it. Oops.

So the problem isn't just landrover engines, but it does seem to have a common cause, water loss going un-noticed.

[rick130]

FWIW I have a new head gasket/t/stat housing gasket and stem seals here ready to fit as mines had the heater let go a few months back although so far everythings ok........

JC recommended the composite gasket unless I had a freshly decked block and new head.

[Tank]

This is the latest emails from the chinese company that is looking into Cast iron heads. Can anyone work out what "stodd" wants to know re: the OEM number in the email below, Regards Frank.

Dear Frank,

Thank you , Someone told me that the 300TDI have the OEM number. Is that correct please ?

Stodd


----- Original Message -----
From: Frank stanton (wlmailhtml:{0E55BC53-D98B-4177-869A-6304B33F059E}mid://00000004/!x-usc:mailto:Frank.Stanton@bigpond.com)
To: China 4x4 Extreme (wlmailhtml:{0E55BC53-D98B-4177-869A-6304B33F059E}mid://00000004/!x-usc:mailto:sales@china4x4extreme.com)
Sent: Monday, February 27, 2012 7:19 PM
Subject: Re: Cylinder heads,


Stodd, thank you, Regards Frank.

From: China 4x4 Extreme (wlmailhtml:{0E55BC53-D98B-4177-869A-6304B33F059E}mid://00000004/!x-usc:mailto:sales@china4x4extreme.com)
Sent: Monday, February 27, 2012 6:39 PM
To: Frank stanton (wlmailhtml:{0E55BC53-D98B-4177-869A-6304B33F059E}mid://00000004/!x-usc:mailto:Frank.Stanton@bigpond.com)
Subject: Cylinder heads,




Dear Frank,

I have contacted some companies in China of the Cylinders Head and now we are waiting for some answer from them. We will come back to you some feedback as soon as we had them.

Best regards,

Stodd

[Casper]

From my understanding,intercooling has very little to do with EGT's.

EGT's are caused by over fueling, worn injectors or over compression (over boosting).

Comparing truck engines Tank to a domestic vehicle engine is like comparing Sydney harbour with your bath tub, both hold water but are far different in every other way.

Just the sheer amount of material in say a Cat truck head or in some cases heads can't be compared nore can they be compared in the work that they do.

The Commercial engines are designed for a specific purpose and meet a specific life span, once they hit that life span, the good operators would rip it out and recondition it so that it lasts that life span again.

If you say that a 300Tdi has a life span on average of 300,000kms then most of what your asking for an improvement to has already met what it is expected to (probably twice what the manufacturer expected) and everything else is a bonus.

Also Commercial engines are generally designed to be rebuilt, Domestic engines are not, yes they can be rebuilt but they will never be as good as they were when they were new unless you do a lot of work and improvements which would then make it better than new but may not may it last any longer.

Even though I'm disappointed in myself for killing my 300Tdi, I'm paying the penalty by having to drive a Falcon ute until I have the money to fix it but I can't fault the car, it gave me 65,000 kms more than what I expected it would and I've owned it since 185,000 kms so it's done me pretty well.

I have spent nearly half my life having to justify repairs to bean counters and the only thing that really matters in the end is if the product meets initial expectations, if it doesn't either buy another product from a different supplier or improve on what you have, neither of which is ever cheap.

Cheers Casper

[B92 8NW]

From my understanding,intercooling has very little to do with EGT's.



I get the impression isuzurover, Dougal et al will disagree:D.

I certainly do anyway.

[isuzurover]

I get the impression isuzurover, Dougal et al will disagree:D.

I certainly do anyway.

Actually the main bit I was going to say was wrong was this:


...

EGT's are caused by ...(over boosting).

...

I posted recently how increasing boost lowers EGTs - quite a lot.

But yes - intercooling effectively increases boost by increasing air density.

[Dougal]

I get the impression isuzurover, Dougal et al will disagree:D.

I certainly do anyway.

Yep.
More boost lowers EGT's. Intercooling makes a massive difference too.

[Bush65]

My issue with the alloy vs iron head on something like a 300Tdi, is not overheating but the mechanical properties of the material. The lower elastic modulus of alloy and creep is the reason the head bolt tension reduces over time, thus lowering the clamping force on the gasket, leading to blown head gaskets, and in turn other problems.

It is cheaper to produce alloy heads.

[uninformed]

what can one do to over come this John? studs instead of bolts?

[Bush65]

what can one do to over come this John? studs instead of bolts?
Studs can help with clamping load, but elastic modulus and creep are material properties (aluminium in this case) - creep (permanent dimension change) also increases with temperature and time.

Edit: I should also add that I don't advocate going to this trouble and expense - polishing a tvrd is an expression used on some other forums and comes to mind here.

[Dougal]

Perhaps a periodic re-tension of the head?

[isuzurover]

Perhaps a periodic re-tension of the head?

How do you do that on bolts that were angle tightened (as per 300tdi head bolts)? You can retighten by a specified angle, however you don't know when the bolt will snap.

[Dougal]

How do you do that on bolts that were angle tightened (as per 300tdi head bolts)? You can retighten by a specified angle, however you don't know when the bolt will snap.

Slacken them off and again tension to the starting tension, followed by the corresponding angle.
If you get a greater rotation than originally, then either the head has compressed or the bolt stretched.

You should only do this a few times for any given bolts lifespan. I've reused my Isuzu bolts, they are visually still good. Same for the head bolts on one of my nissans. At $30 per bolt and 18 bolts for the Nissan it was an easy choice.

[Dougal]

How do you do that on bolts that were angle tightened (as per 300tdi head bolts)? You can retighten by a specified angle, however you don't know when the bolt will snap.

Slacken them off and again tension to the starting torque, followed by the corresponding angle.
If you get a greater rotation than originally, then either the head has compressed or the bolt stretched.

You should only do this a few times for any given bolts lifespan. I've reused my Isuzu bolts, they are visually still good. Same for the head bolts on one of my nissans. At $30 per bolt and 18 bolts for the Nissan it was an easy choice.
Some bolts are well into TTY (torque to yield) at the factory tension, all mine appear to still be in the elastic region, no visible or measurable elongation/necking so I keep using them.

[isuzurover]

Slacken them off and again tension to the starting torque, followed by the corresponding angle.
If you get a greater rotation than originally, then either the head has compressed or the bolt stretched.

You should only do this a few times for any given bolts lifespan. I've reused my Isuzu bolts, they are visually still good. Same for the head bolts on one of my nissans. At $30 per bolt and 18 bolts for the Nissan it was an easy choice.
Some bolts are well into TTY (torque to yield) at the factory tension, all mine appear to still be in the elastic region, no visible or measurable elongation/necking so I keep using them.

300Tdi head bolts are TTY AFAIK. The manual says to replace them when doing the head.

[Dougal]

300Tdi head bolts are TTY AFAIK. The manual says to replace them when doing the head.

Manuals always say that.:angel:

[uninformed]

Manuals always say that.:angel:

yeah I didnt believe my manual when it said not to over fill the engine with oil. :D

[isuzurover]

Manuals always say that.:angel:

Not isuzu manuals ;)

[roverrescue]

from vague memory the 300 overhaul manual states head bolts can be re used s5 times.
For the price of a set though id put in new ones and use the old ones for mill clamp bolts!

[rick130]

300Tdi head bolts are TTY AFAIK. The manual says to replace them when doing the head.

:confused:

My manual says they can be re-used five times so can't be TTY ?

[edit] I just saw Steve's post too.

[Bush65]

How do you do that on bolts that were angle tightened (as per 300tdi head bolts)? You can retighten by a specified angle, however you don't know when the bolt will snap.
Measuring tension in bolts is not simple - I have encounted good methods but they are not cheap or applicable here.

In this example, what I have done is loosen one bolt at a time, then re-tighten. Repeat the process for all head bolts and use the recommended sequence.

I have discovered that 300Tdi head bolts can be tightened well beyond the recomended angles without failing.

I dispute the often stated claim that they are torqued to yield - no one has convinced me that using a specified angle proves that yield was reached. That simply defies logic, and to be pedantic, the alloy steel used for 300Tdi head bolts will not have a yield point.

[isuzurover]

Measuring tension in bolts is not simple - I have encounted good methods but they are not cheap or applicable here.

In this example, what I have done is loosen one bolt at a time, then re-tighten. Repeat the process for all head bolts and use the recommended sequence.

I have discovered that 300Tdi head bolts can be tightened well beyond the recomended angles without failing.

I dispute the often stated claim that they are torqued to yield - no one has convinced me that using a specified angle proves that yield was reached. That simply defies logic, and to be pedantic, the alloy steel used for 300Tdi head bolts will not have a yield point.

Thanks John - very helpful and informative comments as always.

In general wrt torquing to yield - something I have never fully understood... Once you reach the yield point the stress vs strain curve flattens out or even goes down. So if you did indeed torqued a bolt to (just past) yield, the clamping force would/could be lower than just before yield???

And I am not sure what you mean by no yield point? Do you have a stress-strain curve for such bolts to demonstrate?

Steve and Rick - I don't have a Manuel for the Tdi - I was (foolishly) going by statements on here that that was what the manuel said.

[Bush65]

Thanks John - very helpful and informative comments as always.

In general wrt torquing to yield - something I have never fully understood... Once you reach the yield point the stress vs strain curve flattens out or even goes down. So if you did indeed torqued a bolt to (just past) yield, the clamping force would/could be lower than just before yield???

And I am not sure what you mean by no yield point? Do you have a stress-strain curve for such bolts to demonstrate?

Steve and Rick - I don't have a Manuel for the Tdi - I was (foolishly) going by statements on here that that was what the manuel said.
Low carbon steel (AKA mild steel) has a definite yield point, high strength alloy steels do not.

I don't have pics with me, but will attempt an explanation of what happens in a tensile test, starting with low carbon steel.

As tensile load increases, the elongation (stretch) increases proportionaly until the proportional limit is reached - the slope of this straight line corresponds with the elastic modulus (E = stress/strain where stress = load/area and strain = elongation/original length so E = (L x l)/(A x e) ) curve. Near limit of proportionality the elastic limit is reached - where original length will be achieved if load is released. Just after the elongation of the test piece will start to increase with no increase in load - this is yielding and the curve goes horizontal. As further elongation occurs the load starts to drop (because cross sectional area has become smaller - waisting) and the curve dips down. The material begins to work harden and the load starts to rise again to increase elongation. Load starts to fall again because waisting becomes severe. During the last 2 stages the curve resembles an arch. Finally the test piece breaks.

With high strength alloy steel, the curve starts the same and the slope until the limit of proportionality is reached is the same because with steels E is much the same (small differences do occur but are usually neglected except for stainless) regardless of alloy or heat treatment - the value of load at proportional or elastic limit is higher but slope is same. Then as waisting occurs the curve has a similar arch shape until the break occurs. There is no yield point where elongation increases for no increase in load.

Because yield strength changes (material property) we commonly base design strength = 0.nn x yield strength. We avoid yield because it will result in permanent deformation (also formation of a plastic hinge which can turn a ridgid structure into a mechanism (resulting in collapse).

As the high strength steels have no yield point, we create an approximate value on the load/elongation curve by drawing a line parallel to the linear slope, but offset by 0.2% elongation. Where the 0.2% offset line cuts the curve from the tensile test, we have a value to use with our much loved equation (design strength = 0.nn x 0.2% offset strength).

For bolted joints in steel structures, it has become normal and more economical to use high strength structural bolts these are different to common high tensile bolts which are called hexagon precision bolts in the relavent Australian Standard (AS1110 from memory). HSS bolts are designed to be tensioned to the prescribed proof load (near as damb the yield or more correctly 0.2% offset) and the bolt proportions (particularly the head) were developed after much research by the international committee - the Aus Standard is identical to the ISO standard.

The Steel Structures Code (AS4100) and it's commentry have a section on tightening bolts. For bolted joints designed as fully tensioned (tension to the proof load) one of the acceptable tightening methods is part turn (snug tighten then further angle as given in table for bolt length). The other acceptable methods involve tension measurement and torque control (e.g. tension wrench) is generally not permitted.

It is well documented that the part turn method often results in tension exceeding the proof load, but it is not an issue. The standard allows bolts that have been fully tensioned to be re-used once, but only if they are used in the same bolt hole as they were removed from - because permanent deformation of threads, etc. can prevent proper tension being achieved if used in a different location.

With mechanical equipment, where parts are required to be pulled apart and re-assembled more than once, the bolted joints are usually designed for bolts tightened to approx 65% proof load and tables give tightening torque for achieving this tension.

When bolts are tightened to the proof load, the friction forces become so large that torque control results in errors of resulting bolt tension something like 25% - this error has been found in many tests making it unacceptable.

To avoid fatigue failure of bolts subjected to cyclic loads, the best practice is to use bolts (quantity and diameter) so that when tightened their pre-tension is at least 2 times (up to 5 times) the external applied load (in the bolt). Together with this tension, the joint must be designed so that it is considerably stiffer than the bolt. Then during pre-tensioning the bolt elongation is much more than the elongation of the joint. During the load cycles the variation in the tension in the bolt will be small and the variation in the compression of the joint will be large (in proportion to the relative stiffeness). The sum of change in tension of bolt and change in compression of joint equals the external applied load. So fluctuation in the bolt tension (the most important factor for fatigue strength) is much less than the fluctuation in applied load.

Note: it is not a requirement to tighten bolts to yield to achieve ar pre-tension 2 to 5 times the external applied load (we normally use 65% proof load, but where it is not possible to use more bolts or larger dia bolts then we use greater pre-tension, but achieving the pre-tension becomes more difficult.

[Tank]

Low carbon steel (AKA mild steel) has a definite yield point, high strength alloy steels do not.

I don't have pics with me, but will attempt an explanation of what happens in a tensile test, starting with low carbon steel.

As tensile load increases, the elongation (stretch) increases proportionaly until the proportional limit is reached - the slope of this straight line corresponds with the elastic modulus (E = stress/strain where stress = load/area and strain = elongation/original length so E = (L x l)/(A x e) ) curve. Near limit of proportionality the elastic limit is reached - where original length will be achieved if load is released. Just after the elongation of the test piece will start to increase with no increase in load - this is yielding and the curve goes horizontal. As further elongation occurs the load starts to drop (because cross sectional area has become smaller - waisting) and the curve dips down. The material begins to work harden and the load starts to rise again to increase elongation. Load starts to fall again because waisting becomes severe. During the last 2 stages the curve resembles an arch. Finally the test piece breaks.

With high strength alloy steel, the curve starts the same and the slope until the limit of proportionality is reached is the same because with steels E is much the same (small differences do occur but are usually neglected except for stainless) regardless of alloy or heat treatment - the value of load at proportional or elastic limit is higher but slope is same. Then as waisting occurs the curve has a similar arch shape until the break occurs. There is no yield point where elongation increases for no increase in load.

Because yield strength changes (material property) we commonly base design strength = 0.nn x yield strength. We avoid yield because it will result in permanent deformation (also formation of a plastic hinge which can turn a ridgid structure into a mechanism (resulting in collapse).

As the high strength steels have no yield point, we create an approximate value on the load/elongation curve by drawing a line parallel to the linear slope, but offset by 0.2% elongation. Where the 0.2% offset line cuts the curve from the tensile test, we have a value to use with our much loved equation (design strength = 0.nn x 0.2% offset strength).

For bolted joints in steel structures, it has become normal and more economical to use high strength structural bolts these are different to common high tensile bolts which are called hexagon precision bolts in the relavent Australian Standard (AS1110 from memory). HSS bolts are designed to be tensioned to the prescribed proof load (near as damb the yield or more correctly 0.2% offset) and the bolt proportions (particularly the head) were developed after much research by the international committee - the Aus Standard is identical to the ISO standard.

The Steel Structures Code (AS4100) and it's commentry have a section on tightening bolts. For bolted joints designed as fully tensioned (tension to the proof load) one of the acceptable tightening methods is part turn (snug tighten then further angle as given in table for bolt length). The other acceptable methods involve tension measurement and torque control (e.g. tension wrench) is generally not permitted.

It is well documented that the part turn method often results in tension exceeding the proof load, but it is not an issue. The standard allows bolts that have been fully tensioned to be re-used once, but only if they are used in the same bolt hole as they were removed from - because permanent deformation of threads, etc. can prevent proper tension being achieved if used in a different location.

With mechanical equipment, where parts are required to be pulled apart and re-assembled more than once, the bolted joints are usually designed for bolts tightened to approx 65% proof load and tables give tightening torque for achieving this tension.

When bolts are tightened to the proof load, the friction forces become so large that torque control results in errors of resulting bolt tension something like 25% - this error has been found in many tests making it unacceptable.

To avoid fatigue failure of bolts subjected to cyclic loads, the best practice is to use bolts (quantity and diameter) so that when tightened their pre-tension is at least 2 times (up to 5 times) the external applied load (in the bolt). Together with this tension, the joint must be designed so that it is considerably stiffer than the bolt. Then during pre-tensioning the bolt elongation is much more than the elongation of the joint. During the load cycles the variation in the tension in the bolt will be small and the variation in the compression of the joint will be large (in proportion to the relative stiffeness). The sum of change in tension of bolt and change in compression of joint equals the external applied load. So fluctuation in the bolt tension (the most important factor for fatigue strength) is much less than the fluctuation in applied load.

Note: it is not a requirement to tighten bolts to yield to achieve ar pre-tension 2 to 5 times the external applied load (we normally use 65% proof load, but where it is not possible to use more bolts or larger dia bolts then we use greater pre-tension, but achieving the pre-tension becomes more difficult.
John, thanks for your informative post, I don't pretend to understand it all, but I get the Gist of it.
I was wondering if you could offer advice, I am contemplating purchasing a new (alloy) head for my 300TDi, the original has developed a dish like depression around 3 to 4" in diameter and about 8thou. deep. This area is right in the middle of the head straddling #2 and #3 combustion areas. The first time the gasket blew (and it had never run hot until the gasket blew) this depression was noted I had the head skimmed to remove it.
The next time the gasket blew (exact same circumstances) the depression was back, first and second time I used new bolts and torqued to Factory specs.
I didn't have the head skimmed again and fitted a new composite gasket, when it blew again I fitted a laminated metal gasket and old bolts, the depression in the head was still there and the previous composite gaskets all blew in the same spot, at the depression. So far, about 12 months now, (knock on wood) everything is OK.
I intend using ARP head studs and a new laminated metal gasket, I always tap the threads in the block before fitting head bolts. Would you have any suggestions on how to Torque these nuts and washers, would I do it to Factory specs. I cant see where TTY would work on head studs, washers and nuts, I will be using the lube oil for the washers and nuts as supplied by ARP, any information would be appreciated, Regards Frank.

[Bush65]

John, thanks for your informative post, I don't pretend to understand it all, but I get the Gist of it.
I was wondering if you could offer advice, I am contemplating purchasing a new (alloy) head for my 300TDi, the original has developed a dish like depression around 3 to 4" in diameter and about 8thou. deep. This area is right in the middle of the head straddling #2 and #3 combustion areas. The first time the gasket blew (and it had never run hot until the gasket blew) this depression was noted I had the head skimmed to remove it.
The next time the gasket blew (exact same circumstances) the depression was back, first and second time I used new bolts and torqued to Factory specs.
I didn't have the head skimmed again and fitted a new composite gasket, when it blew again I fitted a laminated metal gasket and old bolts, the depression in the head was still there and the previous composite gaskets all blew in the same spot, at the depression. So far, about 12 months now, (knock on wood) everything is OK.
I intend using ARP head studs and a new laminated metal gasket, I always tap the threads in the block before fitting head bolts. Would you have any suggestions on how to Torque these nuts and washers, would I do it to Factory specs. I cant see where TTY would work on head studs, washers and nuts, I will be using the lube oil for the washers and nuts as supplied by ARP, any information would be appreciated, Regards Frank.
Some people have not had luck with the laminated steel gasket in the 300Tdi. You need both head a block to be flat, then all surfaces need to be very clean, nothing that will reduce friction, including finger prints.

I have ARP studs for the head on my 4BD1T, but have not used them with a 300Tdi, which they should help.

When I fitted them (4BD1T) I used the tightening torque that ARP recommended. They had a finer thread pitch for the nut end of the stud than the stock bolts, so using the stock bolt tightening angle would have given a different tension, thus clamping force on the gasket.

I used a tensioning method recommended by diesel engine builders with much more experience than I. Use many small tension steps, much more than the 2 or 3 stages often used (tighten in the same order as stock).

When all studs/bolts are tensioned to the usual 2nd from last stage, release the tension (reverse the normal tightening order and do this in stages). The reason for this is that the mating threads (male & female) settle better. Then tension the bolts by stages as before, to the final tension.

[roverrescue]

Thanks John for the great tech (nice to have you back)

Ben, as an aside, I often find AULRO similar to Fawlty Towers
"I was (foolishly) going by statements on here that that was what the manuel said."

The Manuel in both FT and AULRO will often lead you astray, laughing of course ;)

Steve

[Tank]

John, thanks for that info, I figured ARP would have there own torque figures.
I used the metal laminated head gasket (even though I didn't machine the head, it had a dip in the middle about 7 Thou.).
The composite gasket on each occasion that they blew did so between and 2 and 3 cylinders and surrounds, each time the composite material was missing. I figured at least the metal gaskets wouldn't get blown away, been good for over a year now, knock on wood. Would loved to have been able to get hold of a cast iron head, but not to be. I will buy a new alloy head, laminated metal gasket and ARP studs and hope I get some reliability, Thanks again, regards Frank.

[rick130]

Some people have not had luck with the laminated steel gasket in the 300Tdi. You need both head a block to be flat, then all surfaces need to be very clean, nothing that will reduce friction, including finger prints.


[snip]

That was JC's advice to me, so I have a new Elring composite gasket here + stems seals, etc. for a precautionary change very soon (which is something I've been saying for the last six weeks :angel:)

I reckon 285,000km on the original gasket with 17psi of boost and silly EGT's at times over the last 130,000 km or so, it hasn't done too badly.

[Bush65]

Further to my ealier reply that lacked pics, I found some in by photobucket account that were used in a reply on a similar subject much earlier.

Curve on left shows yielding of low carbom steel
https://www.aulro.com/afvb/images/imported/2013/11/908.jpg

0.2% offset - used as yield strength for high strength steels
https://www.aulro.com/afvb/images/imported/2013/11/910.jpg

Chart that shows what happens when material is stressed past yield over several repetitions
https://www.aulro.com/afvb/images/imported/2013/11/909.jpg

Stress vs strain curves for a few materials
https://www.aulro.com/afvb/images/imported/2012/03/564.jpg

[Davey1000]

Low carbon steel (AKA mild steel) has a definite yield point, high strength alloy steels do not.

I don't have pics with me, but will attempt an explanation of what happens in a tensile test, starting with low carbon steel.

As tensile load increases, the elongation (stretch) increases proportionaly until the proportional limit is reached - the slope of this straight line corresponds with the elastic modulus (E = stress/strain where stress = load/area and strain = elongation/original length so E = (L x l)/(A x e) ) curve. Near limit of proportionality the elastic limit is reached - where original length will be achieved if load is released. Just after the elongation of the test piece will start to increase with no increase in load - this is yielding and the curve goes horizontal. As further elongation occurs the load starts to drop (because cross sectional area has become smaller - waisting) and the curve dips down. The material begins to work harden and the load starts to rise again to increase elongation. Load starts to fall again because waisting becomes severe. During the last 2 stages the curve resembles an arch. Finally the test piece breaks.

With high strength alloy steel, the curve starts the same and the slope until the limit of proportionality is reached is the same because with steels E is much the same (small differences do occur but are usually neglected except for stainless) regardless of alloy or heat treatment - the value of load at proportional or elastic limit is higher but slope is same. Then as waisting occurs the curve has a similar arch shape until the break occurs. There is no yield point where elongation increases for no increase in load.

Because yield strength changes (material property) we commonly base design strength = 0.nn x yield strength. We avoid yield because it will result in permanent deformation (also formation of a plastic hinge which can turn a ridgid structure into a mechanism (resulting in collapse).

As the high strength steels have no yield point, we create an approximate value on the load/elongation curve by drawing a line parallel to the linear slope, but offset by 0.2% elongation. Where the 0.2% offset line cuts the curve from the tensile test, we have a value to use with our much loved equation (design strength = 0.nn x 0.2% offset strength).

For bolted joints in steel structures, it has become normal and more economical to use high strength structural bolts these are different to common high tensile bolts which are called hexagon precision bolts in the relavent Australian Standard (AS1110 from memory). HSS bolts are designed to be tensioned to the prescribed proof load (near as damb the yield or more correctly 0.2% offset) and the bolt proportions (particularly the head) were developed after much research by the international committee - the Aus Standard is identical to the ISO standard.

The Steel Structures Code (AS4100) and it's commentry have a section on tightening bolts. For bolted joints designed as fully tensioned (tension to the proof load) one of the acceptable tightening methods is part turn (snug tighten then further angle as given in table for bolt length). The other acceptable methods involve tension measurement and torque control (e.g. tension wrench) is generally not permitted.

It is well documented that the part turn method often results in tension exceeding the proof load, but it is not an issue. The standard allows bolts that have been fully tensioned to be re-used once, but only if they are used in the same bolt hole as they were removed from - because permanent deformation of threads, etc. can prevent proper tension being achieved if used in a different location.

With mechanical equipment, where parts are required to be pulled apart and re-assembled more than once, the bolted joints are usually designed for bolts tightened to approx 65% proof load and tables give tightening torque for achieving this tension.

When bolts are tightened to the proof load, the friction forces become so large that torque control results in errors of resulting bolt tension something like 25% - this error has been found in many tests making it unacceptable.

To avoid fatigue failure of bolts subjected to cyclic loads, the best practice is to use bolts (quantity and diameter) so that when tightened their pre-tension is at least 2 times (up to 5 times) the external applied load (in the bolt). Together with this tension, the joint must be designed so that it is considerably stiffer than the bolt. Then during pre-tensioning the bolt elongation is much more than the elongation of the joint. During the load cycles the variation in the tension in the bolt will be small and the variation in the compression of the joint will be large (in proportion to the relative stiffeness). The sum of change in tension of bolt and change in compression of joint equals the external applied load. So fluctuation in the bolt tension (the most important factor for fatigue strength) is much less than the fluctuation in applied load.

Note: it is not a requirement to tighten bolts to yield to achieve ar pre-tension 2 to 5 times the external applied load (we normally use 65% proof load, but where it is not possible to use more bolts or larger dia bolts then we use greater pre-tension, but achieving the pre-tension becomes more difficult.



I think we are talking at cross-purposes here as bolting together structural steel bears no resemblance whatsoever to bolting down an aluminium cylinder head that gets hot. Back in my school days in Manchester there was a Physics Practical that had to be done. It would be about fifty years ago now but I can still remember doing it. The experiment was titled "Youngs Modulus of a Steel Wire". Anyhow the test rig involved two lengths of piano wire each about six feet long. One wire had a constant weight applied. The other wire was loaded up with ever increasing weights and between the two wires there was a spirit level with a micrometer screw. A graph of load against extension was plotted and for the most part the graph was linear. Once the yield point was reached however small increases in load produced large extensions. The wire was of course micrometred in several places, an average diameter was then calculated and the maths was done. Amazingly the calculated figure tallied with that in an Engineering Handbook to four figure accuracy, amazing! (and no there was no cheating) Many many years later I worked for a while at British Leyland in Birmingham. As to bolts and bolting the consensus of opinion was that an under-tightened bolt represented money wasted because the same clamping force could have been obtained with a smaller, lighter, cheaper bolt. There were even multi spindle computer controlled nut wrenches that would tighten four or five wheel nuts at one go. The crafty computer would plot the Hookes Law graph in its "brain" and get those nuts really tight! In the case of aluminium cylinder heads there is the perennial problem that the aluminium expands about three times faster than steel. In this case having inch thick bolts made from Kryptonite would not be a good idea. The reason is that the expanding aluminium would crush the gasket and once the engine cooled slightly, the gasket would blow. The ideal bolts are ones that are strong enough to hold the head down but also sufficiently elastic to stretch very slightly when the head gets hot. High class engines have a separate head for each cylinder so warping is not such a problem but we can't all afford those!

If one has an iron engine with iron heads, gasket problems are much less likely. One example of this was a Ford Granada V6 (can't remember whether it was the Cologne 2.8 or the Essex 3.0 litre) After a trip to the shops the car was blowing steam like a steam locomotive as a twig had gone through the radiator. I switched off and left it until the next day. In such cases never lift the bonnet or add water as this can cause trouble, slow natural cooling is best. Once the hole in the radiator was soldered-up the car ran as good as new.

On the 300TDi there are some little vent pipes that go via a plastic widget. These can easily get blocked with rust or radiator sealer and all kinds of air locks will then occur. Very expen$ive! ;)

[jakeslouw]

Not the Essex: those would blow head gaskets faster than you could say "RADIATOR".

I went through so many heads and gaskets in my time, it wasn't funny.

So it must have been the Cologne engine built by the Germans. Not the Essex built in a back yard in England.

[clubagreenie]

Try retorquing a TTY Bolt, I dare you. It'll snap 90 times out of 100. Torque to YIELD (stretch) so next time you'll never get the same torque as the elastic modulus has already been reached, it'll just stretch to failure. Then removing them is difficult as they don't necessarily break off cleanly so you can't necessarily get a stud remover onto them either.

Studs on the other hand, especially those from ARP are very consistent but still require checking to the extent that they supply a spec sheet to be filled in at installation, and whenever they are removed. So you know if they have exceeded their tollerances.

[rick130]

Try retorquing a TTY Bolt, I dare you. It'll snap 90 times out of 100.

[snip]


300Tdi head bolts aren't TTY though. ;)

[Bush65]

IIRC the 300Tdi overhaul manual doesn't specify that the head bolts can't be re-used.

While I recommend against re-use, I have been forced to do so, and also over tightened them by more that 10%, and not one snapped :angel:

[Tank]

This info from Land Rover Workshop Manual for 300TDi so LR seem to think that head bolts are NOT to be reused and that NEW bolts are to be fitted when fitting new head gasket, Regards Frank.

Remove

1.

Remove rocker shaft.

2.


Remove fuel injectors.

3.


Remove glow plugs.

4.


Using sequence shown, progressively slacken

then remove and discard 18 bolts securing
cylinder head.
5.


Using assistance, remove cylinder head.

NOTE: Dowel located.
6. Remove


Cylinder head - refit

1.

Ensure that mating faces of cylinder head and


block are clean and dry and that 2 locating



dowels are fitted in cylinder block.



2.



Lubricate threads of new cylinder head bolts


with engine oil.



3.



Check that cylinder head bolt holes in cylinder


block are clean and dry.



4.



Rotate crankshaft in a clockwise direction until


pistons are half-way up cylinder bores.



5.



Position the selected cylinder head gasket on


cylinder block ensuring that word "TOP" is



facing upwards.



6.



Using assistance, fit cylinder head ensuring
that it is located on dowels.

[rick130]

Frank, my manual (genuine LR Service manual for Defender, 300Tdi, 97MY, pg. 22) says the head bolts can be used up to a maximum of 5 (five) times :confused:



NOTE: Cylinder head retaining bolts can be used up to a maximum of five times


[edit] I also found on page 18 of the overhaul manual the section you've quoted.
I'll have a look through the Tech bulletins and see if anything pops up.

[uninformed]

LR just covering their bases....

[Blknight.aus]

Personally...

tdi300 headbolts can be reused 3 times

I recommend replacing them if you don't know or if you've already reused them once so that IF you have to reuse them in the field you have one more shot left on them.

I've only ever snapped bolts on the tdi that have been done more than 3 times already (known by good service histories and reciepts/owner knowledge from doing their own work.)