overheating, which way does the water cycle?

[lux201]

Hi all, I am having an overheating problem with my 96" 300tdi disco:(, water pump is new and thermostat is new.
when it gets hot the bottom radiator hoses are cool enough to hold but the top hoses are almost too hot to touch:confused:.
I am getting pressure buildup in the water system, so first though would be head gaskit but fume tests came back negative and no water in oil or visa versa.
next step is to try to work out if there is a block somewhere, I have bypassed the heater for the moment but this diddnt change anything, I am going to get the radiator rodded next week and tomorrow I am going to check in front of it for debree but for now the disco is barely drivable, it just gets hot too quickly.

Im interested if anyone knows whether the water flows downwards through the radiator, considering the extreme difference in hose temps this would back up my blocked radiator theory.

[Blknight.aus]

blocked radiator.

as a minimum get it hit with a coolant flush treatment, then a flush gun and then again with the coolant flush but you're probably better off getting the radiator rodded.

oh and to answer the question on he edit.. (I promise one day I will think about not posting till the coffee kicks in)

most of the time coolant flow through the radiator is from top to bottom.

[roverrescue]

300tdi discos and fenders have 3 or 4 core (depends on year) double pass cross flow radiators.

End tanks are are at left and right. Water comes from thermo to top of PS end tank, runs across the top half of the rad to DS end tank then back across to hose at bottom of PS end tank. There is a baffle at the half way point in the PS tank to create the double pass.

With this set up blocking just 1/4 of the cores means you have a 50% blockage. Normally it is the lower cores that fill with gunge. Your radiator needs rodding.

Steve

[lux201]

Thanks fot your help guys:), I will report the result of the rodding.

Cheers,
Jarrod.

[lux201]

ok, radiator now rodded(quite an easy job, will post photos in a while) Unfortunately no difference:( but im starting to think it may be the guage, whilst appearing hot(last white line before the red) I hopped out and slightly undid the cap to relieve some pressure, and quite comfortably ran my hand under the water being pushed out by pressure, it was hot but not as hot as the guage would indicate, infact I could leave my hand under it all day.. but there was alot of pressure pushing that water out, I could hear it bubbling up through the system when pressure was relieved.. also I noticed that when ignition is off the temp reads about 1/4ish or more less than with engine running.. next will be to check over the earths.
Does anyone else know if that sort of pressure is ok under a usually normal running temp?

[Blknight.aus]

maximum system pressure is about 14psi. normal operating pressure would be 8-10

you rodded the radiator yourself? and what cap did you remove to get the coolant to flow out from?

[danny11987]

not queite same problem, but in my d2 v8 im losing coolant. thought it was from throttle heater so disconected, still losing it. have to top up 2-4 liters every 500km

[Davie]

There is a post on here somewhere about the headgasket and symptoms, worth a check

[Rover18]

Hi all, I am having an overheating problem with my 96" 300tdi disco:(, water pump is new and thermostat is new.
when it gets hot the bottom radiator hoses are cool enough to hold but the top hoses are almost too hot to touch:confused:.
I am getting pressure buildup in the water system, so first though would be head gaskit but fume tests came back negative and no water in oil or visa versa.
next step is to try to work out if there is a block somewhere, I have bypassed the heater for the moment but this diddnt change anything, I am going to get the radiator rodded next week and tomorrow I am going to check in front of it for debree but for now the disco is barely drivable, it just gets hot too quickly.

Im interested if anyone knows whether the water flows downwards through the radiator, considering the extreme difference in hose temps this would back up my blocked radiator theory.


looks like a kinked hose somewhere or a faulty thermostat try to remove thermostat and see if it heats up got to be your thermostat

[roverrescue]

How long had engine been running before your "pressure" test?
The guages in both disco and fender are "flat spotted" from thermostat temperature 85ish degrees right through to about 105 degrees to show normal. If your factory gauge is showing hot the temperature "should" be 105 plus which you shouldnt be able to put your hand under unless you are the terminator... So I would have to agree with your assumption it may be gauge related.

BUT/

I would argue if the system is highly pressurised WITHOUT heat then you may have combustion pressure getting to the water jacket.

P=VT in a closed system Volume is constant... therefore Pressure is proportional to Temperature... the pressure is generated by temperature which in a tdi runs nominally at 80-100 degrees. If you can "put your hand under it all day" me be guessing it is lower than 80 which means it may be pressurising at sub-optimal temperature which leads me to think you may have combustion pressure getting to the water jacket.

Do you have a way of measuring actual water temp seperate to the factory "guage"?

Steve

[lux201]

maximum system pressure is about 14psi. normal operating pressure would be 8-10

you rodded the radiator yourself? and what cap did you remove to get the coolant to flow out from?

yep, it was quite easy with the right equipment, before we started we went down to a radiator repair place and he gave us some tips and also provided the solder rods, some sort of proper radiator flux(clear liquid, maybe some sort of acid) and the rodder which is basically just like a vehicle dip-stick with the twisted end cut off, infact I think that would work, he provided the lot for $20(top bloke)

Pics-

The items Provided
http://img245.imageshack.us/img245/5013/imag0043l.jpg (http://img245.imageshack.us/i/imag0043l.jpg/)
Thankfully my mate had an oxi and was happy to help out
http://img233.imageshack.us/img233/5277/imag0045q.jpg (http://img233.imageshack.us/i/imag0045q.jpg/)
We used the oxi to remove the solder, just made sure we removed anything that could melt first, as we heated we also scraped out the old solder
http://img219.imageshack.us/img219/4553/imag0046f.jpg (http://img219.imageshack.us/i/imag0046f.jpg/)
Then came the rodding, thats my mate having a go, I then sat down and went through it twice more
http://img810.imageshack.us/img810/2240/imag0049vm.jpg (http://img810.imageshack.us/i/imag0049vm.jpg/)
Simply attached a hose to the bottom so water pressure would assist with cleaning
http://img149.imageshack.us/img149/5870/imag0050i.jpg (http://img149.imageshack.us/i/imag0050i.jpg/)

At this point my phone went flat, so I couldnt take any more photos, after the rodding we cleaned the surfaces ready to solder back and reversed removal procedure, my mate had made up a pressure tester to test the final result.
Although it diddnt fix my problem I am glad I now know how to do this and that I know it has been done.

[lux201]

OK, been at this now for 14hrs solid and I think thats it for tonight.

Previous owners Attempts:

New thermostat,
New Water pump,
Got the water system fume tested



Things I have done:

Radiator Rodded,
Engine flushed,
Thermostat removed,
Additional earth from negative to engine(havnt tried to body yet)
checked for kinks etc
not sure about this but thought i'd give it a try, filled system with fresh water and removed usual airlocks, when cold I placed a balloon over filler port, waited a minute and the balloon started to fill up, after about 5 mins the balloon was at about 50% capacity with vehicle at idle speed, I had a sniff of the air in the balloon to see if I could smell exhaust(or any contaminant) and nothing, smelt like clean balloon, my mate agreed on this.

basically what is still happening is this: after fresh fill of water and usual airlocks removed we take it for a drive, everything seems fine for about 10mins, the temp sits a little under half way, then all of a sudden, out of the blue it will start climbing rappidly, once it hits what I assume is the danger zone(last white line before the red) we stop and check the hoses and we can grab them without problem(with thermostat in the top one is a bit hotter) if I open the filler cap at this point just a little to relieve pressure we get mainly water spilling out which is only warm but there is quite alot of pressure.

I am worried it may be the head but it is starting to look that way:(

[Blknight.aus]

pump impeller may be shagged, and as its a diesel unless you use a temperature sensitive coolant the usual sniff check that works on a petrol engine wont work.

see if you can extend the radiator hoses from the engine into a large bucket and run it up without a thermostat fitted to see what the flow rate from the pump is...

is the thermostat shagged (Ive had new ones that wouldnt open before)

is the thermostat in the right way round?

[roverrescue]

Im banking on delaminated head gasket - gasses through the composite gasket at pot 2 or 3 to the water jacket.

If it blows a ballon up at idle when cold I wouldnt imagine you wouldnt smell too much other than air... at idle the engine is pumping mostly air. Bugger all fuel being burnt to smell combustion products.

The only thing I dont get is you say thermostat removed, driving around temps start to climb after only 10 minutes... seems quick in my experience of limping head gasketted 300tdi s. With the thermostat removed 10 minutes is pretty quick - unless you are pegging it up hill.

Can you directly measure the actual water temperature in the head - factory gauge is not reliable.

The water in the resevoir really only has a direct connection to the main flow from the bottom hose, if there is a water restriction in the block or pumping problem the water in the head (where the factory sensor is) could be boiling but not circulating enough to increase the temp in the resevoir.

I like Davids idea of running the bottom hose and top hose from a big bucket just to check on circulation.

Steve

[lux201]

ok, up and had my coffee and time to get back into it, first of all I will be pulling out the water pump for a visual inspection, failing that I will give Dave's water test a go and then thirdly a compression test..

honestly I would be happy to know it was a head gaskit but unhappy to go ahead and just do it if it diddnt fix the problem, it wouldnt be the first time as I have owned many ford falcons.

I was wondering if anyone knows the correct procedure for doing a compression test on the 300tdi, I think it will tell me the truth.

Thanks a heap for all your suggestions, I will post my results.

Cheers.

[Blknight.aus]

get a diesel compression test unit. the gauge should be calibrated with a small large scale step from 0 to about 100psi and then cover out to about 600psi in small scale large steps Dont use any gauge that cant handle at least 400 psi

with the engine cold

remove all the glow plugs, remove the fuse or the relay that drives the glowplugs
remove the wire from the fuel pump solenoid
attach the diesel compression test unit to glow plug hole 1
crank the engine for 3-5 compression strokes.
not pressure
repeat for pots 2,3+4
put the glow plugs back
put the wire back (dont forget that bit)

10% variance from lowest pot to highest is the limit of acceptability. and IMHO more than 5% is questionable.

repeat with a hot engine, as a general rule, if the variance is more than 5% on a hot engine then its time to start pondering about contemplating new rings. If it gets worse then its time for headwork in one form or another and a leak down test is in order to work out what


as a precautionary step for doing a leak down test its worth while sourcing or making a leak down adaption for the glow plug to make one just gut an old glow plug and weld an air fitting onto the top If you get more than 10% varience on a hot engine conduct a basic leak down test.

plug the adaptor onto the pot with the lowest compression set that piston to post TDC on the power stroke and lock it in gear, or lock the crank by means of the crank timing pin or a socket and breaker bar on the main pully, remove the dipstick and block the crank case ventilation tube with a finger from a rubber glove.

when you put the air on listen for the escaping air.

out the inlet its the inlet valve
out the exhuast its the exhuast valve
out of an adjacent piston its a delaminating head gasket that hasnt compromised the cooling system yet
out the cooling system its the head or the gasket
out the dipstike tube its the rings.

Drop the pressure off and using the big nut on the pully OR by letting the engine turn over step by step against the transmission repeatedly apply the air to check the leakdown past the rings at about 15 degree steps of the crank, this will give you an indication of oval worn bores which means its pretty much time for a rebuild.

[lux201]

ok, I checked out the pump and sure enough as the previous owner said it appeares brand new also threw a hose into every orifice and there seemed to be no water restrictions.

I have now taken the head off and cleaned it up ready to get it shaved and tested, I figured it would be a nice thing to have done anyway.. I could not clearly see where a water breach could have been occuring but there was an abnormal, burnt sort of look between the 2nd and 3rd cylinders, I suppose will know for sure when the test has been done.

at the end of the day I only payed 1,800 for a 96" 300tdi disco that only has 174,000 k's on it so I dont mind spending a little more, I will also do the timing belt while I wait.

I will let you all know how it turns out.

cheers.

Head pic:-

https://www.aulro.com/afvb/ (http://img375.imageshack.us/i/imag0051q.jpg/)

[Blknight.aus]

thats a pretty good indicator of a delaminated head gasket.

[lux201]

hmm, after closer inspection I have found 2 small cracks coming from my glow plug ports in cyl 2 and 3:(, im hoping this is not an area of critical structural integrity, if so I wonder if I am able to get the ports drilled to stop the cracks from growing any further.

pics provided:-

http://img195.imageshack.us/img195/1893/imag0054h.jpg (http://img195.imageshack.us/i/imag0054h.jpg/)
http://img823.imageshack.us/img823/1043/imag0055r.jpg (http://img823.imageshack.us/i/imag0055r.jpg/)

[roverrescue]

Those glow plug ports always seem to crack on 300tdi... unless the crack is super deep it is of no concern.

As I suspected that looks like a delaminated head gasket between 2 & 3.

Use the MLS head gasket as opposed to composite after you have the head lightly skimmed - assuming it is true enough for just a light skim.

Good to see you found the problem ;)

Steve

[lux201]

Those glow plug ports always seem to crack on 300tdi... unless the crack is super deep it is of no concern.

As I suspected that looks like a delaminated head gasket between 2 & 3.

Use the MLS head gasket as opposed to composite after you have the head lightly skimmed - assuming it is true enough for just a light skim.

Good to see you found the problem ;)

Steve

ok, great thanks :BigThumb: I was actually wondering about this.

[lardy]

how ya getting on?

[lux201]

how ya getting on?

well now that I know it is the head gaskit im somewhat glad to finally see some light at the end of the tunnel, its been 2 solid days and a full night working on this, and to be honest I did think it was a little under powered by comparison to my older 200tdi disco(im going to miss that thing:().. But at the end of the day I see it all as a quality vehicle bonding experience, next will be the rear main seal.. I might do the clutch, spiggot, throw-out bearing and seals at the same time.. but thats another project, I still have to transfer the wheels, suspension and flexi flares from the old one as well, looks like I have a busy week ahead..
now, if only this rain will give us all a break!

[lardy]

Nothing like getting gunked up with **** to find out what makes a motor tick!
I am busy as this weekend as well nothing like it really ...although it can be a pain in the arse the feeling of self satisfaction after completing a job ahhh great!!!

[lux201]

Nothing like getting gunked up with **** to find out what makes a motor tick!
I am busy as this weekend as well nothing like it really ...although it can be a pain in the arse the feeling of self satisfaction after completing a job ahhh great!!!

Agreed! ..problem is that my other half now knows I enjoy it(must have over heared all the drinking and laughing and carrying on).. so no longer have an excuse to get out of other s*** around the house:(.. I tried telling her washing clothes and such can be enjoyable.. ..but then I got that look..

[lux201]

OK, I got my head back today, it passed integrity test and is all shaved and ready to go:D, I have cleaned up the block using a razor blade then cleaned it off using metho and a green scratchy finished with a buff off with a clean rag, that took me most of the day but now its nice and clean:).. now just awaiting gaskits, bolts etc in the mail, they should be here tomorrow.

[lux201]

OK, its done!! the head is back on and everything is running nicely :D I did the tappets before turning it over just incase the clearances had changed due to head shave, new gasket etc. took it for a drive and temp is nice and there is deffinately a noticable performance increase.

To be honest im kinda glad I went through everything else first, I now know it is all done.

I will drive it for a day then drop water and oil and give it a full service.

Total Cost:
Head Shave and pressure test - $150
Head Gasket, tty bolts and rocker cover gasket - $185(after delivery)
after petrol and beers total came to around $380.

Very happy!!
Thanks for all your help:D.

[LOVEMYRANGIE]

I could not clearly see where a water breach could have been occuring but there was an abnormal, burnt sort of look between the 2nd and 3rd cylinders, I suppose will know for sure when the test has been done.



http://img375.imageshack.us/img375/9814/imag0051q.jpg (http://img375.imageshack.us/i/imag0051q.jpg/)

Never really understood why these exhaust valves were placed ajacent each other. Its right up there with the Nissan ZD30 having the ports paired front and rear instead of left and right and both sharing a common port runner ;/
It ends up being the hottest part of the head. With all the new 300 heads ive sold in my time, this was a reasonably common area for failure with them.

With the glow plug holes, a quick nip with a diegrinder to the square up the sharp edge and stress relieve it makes a difference to it cracking, bit this is generally not an issue.

Good to hear its all sweet again!

Cheers

Andrew

[roverrescue]

Andrew I have wondered this too, and the only (this is weak I know;)) thing I come up with is it gives two exhaust runners to mount the hairdryer up to.

I wonder if with more MLS (multilayer steel) gaskets getting used whether we will see less delamination failures in that area?

S

[lux201]

Andrew I have wondered this too, and the only (this is weak I know;)) thing I come up with is it gives two exhaust runners to mount the hairdryer up to.

I wonder if with more MLS (multilayer steel) gaskets getting used whether we will see less delamination failures in that area?

S

i'll let you know how many K's I get out of mine ;)

[Disco1Newbee]

Additional earth from negative to engine(havnt tried to body yet)


What did you go to achieve this? Its something i need to do and not really sure what it is I should be doing.

Thanks

[lux201]

What did you go to achieve this? Its something i need to do and not really sure what it is I should be doing.

Thanks

Most people seem to wire up a cable from the negative terminal on the battery to a bolt that holds the seat to the floor, instead I just copied the setup from my older 200tdi disco and ran a fat cable(used a car amplifier cable) from the negative terminal over to one of the bolts that hold on the aircon compressor.

Although I assume it is I couldnt give you a conclusive answer as to whether this is the right way to do it though as it seems my earth was already ok.

I can take a photo if it helps, just let me know.

Cheers.

[Blknight.aus]

it provides additional earth tothe battery and prevents voltage loss.

the best run is from the bolt that holds the startermotor direct to the battery

that gets you a good start.

then run a braided earth strap over the the chassis I normally do this from either the alternator to the bolt on the engine mount or from one of the PTO cover bolts to the gearbox mount (do it onto the chassis side of the mount)

If you're running back to body instead of back to chassis or back to negative cables for aux power then its advisable to make another earth lead that goes from the body to one of the other main earth points.

In the V8's install an earth line from the coil mount that runs back to the lower alternater bolt. this helps with conducting the spark voltage.

[LOVEMYRANGIE]

Andrew I have wondered this too, and the only (this is weak I know;)) thing I come up with is it gives two exhaust runners to mount the hairdryer up to.

I wonder if with more MLS (multilayer steel) gaskets getting used whether we will see less delamination failures in that area?

S

Thats ideally why MLS are used. The main thing with them is you cant really compress them any further than the thickness of the layers designed crush and when they do they bond together. The fire ring is a lot stronger on an MLS and doesnt suffer burnout like a composite.
Composite gaskets are cheap to make but the material will begin to breakdown over time from things like coolant and oil soak.
The other main feature of an MLS is that where the above happens in a composite, this can also lead to the the head warping and developing cracks as the face tension changes and becomes uneven.
An MLS also has better heat transfer equalising block/head face temperature. As before, with the fire ring compressed against steel layers that transfer heat, a burnthru is infinitely less likely than in a composite where the fibre material insulates rather than transfer.
Your only other option is to go down the nitro and methanol route and go full machined copper o ring with grooved deck and head!

Cheers

Andrew