V8 Head Gasket Tips and Tricks?

[Disco_Harvs]

Hi All,

In a day or two I'd like to replace the head gaskets on my disco as they are starting to weep externally. I've bought all the gaskets and some gasket glue but I was just wondering if there's anything I should be aware of or any special tools I need before starting the project?

I've bought one of the disco CDs off this site and as far as I can tell it's a pretty straight forward job of removing rocker covers, rockers etc and then the head bolts. From what I could tell none of the timing gear needs to be touched. Is this correct?

The engine in my disco is the 4.6L rangie engine and whilst my manual doesn't cover the torque settings on the 4.6L I'm guessing the head torque should be the same as the 3.9L. Is this a bad guess?

Any advice would be appreciated.

Cheers,

Harvs

[stevo]

get some wet and dry sandpaper to clean the block and head surfaces
and when you pull parts off such as push rods cam followers etc keep them in order so everything goes back the same.

Not sure about the bolt torque but do not assume it is the same someone on here will have the answer also be carefull about putting sealant on headgasket surfaces not allways a good idea I have pulled heads off and found some idiot has used silicone sealer

[Disco_Harvs]

get some wet and dry sandpaper to clean the block and head surfaces
and when you pull parts off such as push rods cam followers etc keep them in order so everything goes back the same.

Not sure about the bolt torque but do not assume it is the same someone on here will have the answer also be carefull about putting sealant on headgasket surfaces not allways a good idea I have pulled heads off and found some idiot has used silicone sealer


Thanks Stevo,

I was a little hesitant about sanding the head and block. I was planning on just getting a plastic scraper and chipping off any residue and then cleaning the rest with a bit of metho/petrol. The engine was brand new when the previous owner put it in and this is the first head gasket change so I'm hoping there wont be too much to clean up. If I do have to use wet and dry rub what grade would you recommend?

As for the sealer, I bought some head gasket sealant from a landrover wrecker here in SA. They said it was suitable so I'm just going on that. One question I do have is how much do I use? I was planning to run a small bead of sealant around every metal part that the gasket touches. ie a bead on both the block and the head. Oh and I was going to do it in the following order.

1. Run sealant around block and let it sit for 5mins etc.
2. Press on the gasket.
3. Run sealant around the head let it sit.
4. Put the head back on and start torquing it up.

Does this seem reasonable?

Sorry for all the questions, but I want to make sure I do it right the first time round.

Cheers,

Harvs

[EchiDna]

are you sure the heads are flat? this can cause the weeping in the first place... you can have the machining done for (relatively) few dollars compared to having someone do the whole job.

Torque wrench settings vary from motor to motor - make sure you use the right settings for the specific motor and make sure you re-torque it and change the oil and filters (if water got into the oil) and flush the radiator again (if oil got in the water) after a week or two as the gasket beds in. nothing worse than doing the hard work and being too busy to re tighten the head bolts.... then the head gasket blows again and you are back to square one...yeah , I've been there and done that on my first car... :rolleyes:

[stevo]

I used 800 grit then finished off with 1200,scotch bright is a good idea as well,the torque and yeild method does not need redoing as the chance of breaking bolts is high and replace your head bolts,I did mine (td5) the old bolts had stretched about 0.40mm so reusing these would cause them to break.

You can buy the torqgue(delete button on computer has stopped working so can't delete spelling mistakes) torque guage at super cheap ($25)
and as PLR has pointed out read and reread the manual

[camel_landy]

It's been a while since I did a V8 but here goes...

The head bolts are put in with thread lock... Make sure you clean the threads out.
When cleaning all the old crud off the block & heads, I usually just use a razor blade.
When the heads are off, check that they'll flat by using a flat edge.
The inlet manifold comes off as one unit but can be a sod trying to get it out of the way. I usually undo the injector connectors, etc... but others I know just tie the whole lot off to one side. Just do whatever works for you.
The only bit I've found to be fiddly is getting the valley gasket seated before fixing everything else over the top. The rubber bits at either end can be a bit of a sod sometimes.

It's not too difficult a job assumimg you don't hit problems... My biggest problem was snapping a head bolt while removing one of the heads. It was one of the lower bolts towards the back of the engine and it snapped off inside the block. I was sh1tting myself while we were drilling it out!!! :eek:

M

[Disco_Harvs]

Thanks guys,

Sorry for the late reply, I've been running around trying to work out what's what and whether or not I should still be doing this job myself. But what the heck what's the worst that could happen? ....... Actually don't answer that.

PLR, the gaskets that I've got are some graphite flex gaskets from Durapro (some japanese company) model number GSBR290D if that helps. There doesn't seem to be any built in sealant bead so I'm guessing these are to replace the factory tin gaskets.

The engine number prefix as best as I can tell is 'S' however it could be a 8 5 or 6. Doesn't look like a B though. As for the ratio number I'm not sure what that is but there is a stamp of GR8.37:1 if that helps.

The other gaskets I have are the two little rubber gaskets and a large U shaped gasket (I'm guessing this is the valley gasket).

As yet I don't have any replacement head bolts so I'll have to head out on the weekend for a set of these.

Ok, so far I have this.

1. Head bolts aren't reusable so get some new ones
2. Clean out the threads
3. Clean surfaces with scotch guard (wet rub just scares me)
4. Check for a warped head with a straight edge
5. No sealant should be used on the actual head gasket.
6. torque settings are done once as per the manual ie. Torque to the specific Nm then via degrees for the rest.
7. Read the manual again and again
8. If a head bolt snaps put the disco on a trailer and take it to a professional :)

One questions that still remain is where does the gasket goo go then? The manual doesn't seem to mention applying goo at any point in time. Actually I've found it quite vague in the whole engine overhaul section. Am I looking in the wrong spot or does it just assume I know what I'm doing. It gives details about the head gasket torque settings, but I've found no details at all on the fitting of the valley gasket etc. All it has is an exploded diagram to show where things go.

Another question I have is, are the exhaust gaskets reusable? I don't have any new ones lying around so I might need to get some at the same time as the head bolts.

Once again thanks for all the help,

Harvs

[Disco_Harvs]

Thanks for that Peter,

I think I've at least got enough info now to start the job and see where it takes me. I had assumed it was a 4.6 head but after that info, I chased up the mechanic who put the engine in and it was actually the 3.9 head bolted onto the 4.6. Now at least I know what I'm dealing with. As for whether or not the bolts are reusable I guess I'll just have to wait and see.

Cheers again,

Harvs,

[PhilipA]

Regardless you should not use "Gasket goo" on the gasket, and it says this in the manual
The sealant on the gasket from new should be just a thin blue or maybe red line around the water holes.
The sealant recommended by Rover is "Hylomar Blue" You can get it in a spray can or tube. You can spray it safely on the area where the head joins the manifold. I suggest spray it on the gasket, and a bit around the water holes at the front and back of the head. As it dries beefore you do things up it does not squeeze everywhere like silastic.
You are only supposed to use sealant (silastic)at the very ends of the rubber gaskets under the valley gasket, where they touch the heads. I have never had a leak through these unless the head gasket is pressurising the crankcase.Its a bit tricky doing up the bolts which hold the steel ends onto the valley gasket. they should only be finally tightened after the valley gasket has been torqued at the head faces
Tip- The valley gasket has "Front" on it. Put that to the front. Trust me.
Regards Philip A

[Milton477]

Thought you might need the manal to complete the job. Please see the attached pdf file. I think that have attached it correctly, let me know if you have a problem. Good information about rover V8 can also be found at http://rpiv8.com (http://rpiv8.com/)

I have replaced head gaskets several times. Always used new bolts with only a little engine oil for lubrication. Head gaskets go straight on without any sealer.

Good luck

143

[4X4V8]

This is all great info guys, thank-you. I found out today my 99 DII V8 with only 111,000km has a leaking cyl head :mad: , among other engine leaks, so I'll be taking the heads off soon, too...pretty disappointed such a young engine needs heads off.

What's a ballpark figure for a good gasket set to do the above - and what brands would you avoid (already taken note of composite v tin head gaskets)? Has anyone found a worthwhile price advantage buying o/seas, eg Famous Four in the UK?

[Pedro_The_Swift]

This is all great info guys, thank-you. I found out today my 99 DII V8 with only 111,000km has a leaking cyl head :mad: , among other engine leaks, so I'll be taking the heads off soon, too...pretty disappointed such a young engine needs heads off.

What's a ballpark figure for a good gasket set to do the above - and what brands would you avoid (already taken note of composite v tin head gaskets)? Has anyone found a worthwhile price advantage buying o/seas, eg Famous Four in the UK?

how long have you had it 4X4V8?:mellow:

[4X4V8]

I've had it a week. Yeah, welcome to the LR ownership experience ;) . I am not too worried about it. Lesson is never assume, and always get a LR expert to check over the car. I haven't seen inside a 'ol Rover engine since I replaced the lifters in a P76 in 1983, so it'll be fun... well, that's what I keep telling myself, anyway...

[Pedro_The_Swift]

so if its a D2, its a THOR?
and it could be 10 or 14 bolt heads?

[DEFENDERZOOK]

i would be sending the heads off to have the valves lapped in.......
unless things have improved on the later models......


a little trick to cleaning the heads and the block.......
scrape off any old gasket with a razor blade or scraper.......then instaed of using sand
paper which will wear where you rub......and you can actually have an uneven surface.....
use a honing stone........just a cheapo from a $2 shop will do.....
it does a larger area and it does it a lot flatter than sand paper.........
especially between the bores....which is where you always manage to to have the most
pressure when sanding.....and is usually the spot where the head gasket blows first.....
and use oil with the stone to stop it from getting all clogged up........

[4X4V8]

Thanks PLR, it's always good to have some knowledgable input. Mine is an early D2, definitely a THOR engine and it's weeping coolant out of the left cylinder head to block join at the rear. It also has a throttle body warmer leak and a constant ticking, which has been diagnosed by a specialist as worn rockers. I will inspect the valve train for wear before I go and replace anything, as it could be cam and lifters as you mentioned.
I am a little disappointed with LR quality, esp with an engine they should have been familliar with after 30 years building 'em, despite the fact it was an upgraded version. I owned a 16-year old German V8 sedan before the Disco with 160,000 km and the engine was perfect, had never been apart, ... I sold it for its mostly age-related problems (heater core etc) and rarity, which meant I spent too much time fixing it rather than driving it. I had the misguided belief that a much younger car would not be perfect, but would be an improvement. I can't believe I'm in the same situation again with a car 1/2 its age and with much lower kilometres...:(

[PhilipA]

Unless you go to the snow a lot, just loop the throttle body warmer lines. Apparently this is a common failure .When I fitted the Thor to my 3.9, I asked Graeme Cooper who gave me that advice. Mine has always run perfectly, but it depends. If you go to a very cold wet area you may have problems.

My 3.9 had the same head gasket failure. Your car has probably been overheated at some stage, as you will find that the head has warped, and needs a skim. So don't be too hard on the quality. Its probably the operator or mechanic.
Maybe the throttle body leak ran it out of water from someone never checking.
Regards Philip A

[Disco_Harvs]

Hi All,

Well the project has started. It has been much slower going than I originally expected, thanks to my lack of knowledge, my computer crashing before I could get the manual printed off, and my lack of motivation when the temperature is about 0 degrees.

Last night however I came up against my first real problem. The trumpet manifold has been put on previously with a LOT of sealant. I can't budge the thing. I've tried levering it up, knocking it sideways with a block of wood and hammer and nothing seems to shift it.

My next plan is to put a chisel in the join and try and prise it off but is this a stupid idea? Has anyone done this before and does it damage the alloy. Any other ideas on how to get it off would be greatly appreciated.

PLR
As always thanks for the tips. I'll pull out the lifters out and check them. This job is much bigger than I originally thought so I'm keen on checking everything whilst it's all off.

4x4v8
In regards to head gasket price I got my complete gasket set for $260 which included a $30 dollar tube of sealant. I didn't get the factory ones though with the bead of sealant. Whether or not this is a bad thing is yet to be determined.

My tips so far for anyone else thinking of doing this job.
1. Make sure you have a lot more time than you think it will take.
2. Make sure you depressurise the fuel line before you pull everything off. The manual actually states this but I, as always, rushed ahead :D
3. Get some tips on how to remove that stupid bottom radiator hose. I ended up removing the arm that goes up to the expansion tank, bending it down and draining the majority that way. I'll be stuffed if I can get the entire bottom hose off. I tried hot water to soften the hose but still no luck.
4. Make sure you have some tiny spanners. A lot of my hose clamps are in places that can not be undone by screwdrivers, so a spanner is the only solution.
5. As others have said, and as I now say, read the manual. The step by step guide really is quite handy.

[Disco_Harvs]

Hi it's me again,

I've now got the heads off and I was wondering if anyone could tell me what type of bolts I have got. The heads are 10 bolt heads but the bolts don't seem to have any sealant on them (as suggested) and the tensile rating seems to be quite large. I'm starting to think they may be reusable. Any ideas?

Thanks in advance,

Harvs.

p.s This is the first time I've inserted files so it may take me a few attempts.

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[PhilipA]

If the washer is integral , they are stretch bolts. Ie you tension them to a certain amount then you turn them a predetermined amount say 90 degrees, and you buy a gauge from a car accessory place. The gauge is just a protractor that fits over a 1/2 inch drive. The instructions should be in the manual , or if I recall came with my head gaskets.
Regard sPhilip A

If I recall the stretch bolts can be used twice or three times . I think Rover recommend that you change them each time but they are mucho dinero.
Regards Philip A

[arthurking83]

.....I owned a 16-year old German V8 sedan before the Disco with 160,000 km and the engine was perfect, had never been apart, ... I sold it for its mostly age-related problems ......

My '79 RR has done 496,000 klms on original ....just about everything!
I got it in '88 with 148,000. Still have it, and it's age related problems :p

Oils leaks :lol:, tickety cams/rockers/lifters/springs, drove it for 2 years with a rotted radiator...from Melb to Ayer Rock, Eucla, Lake Eyre, Slim Dusty style....we checked every nook and cranny, and just assumed the temp gauge had gone haywire showing hotter than normal.

Some people have luck, others make their own luck.....
....me....I guess I've been lucky with my 19 vehicles, mostly Rover(V8's!! about 10-12) and possibly 2-3+ million klms...I lost count !

Apart from ALL the electrical failures, on all my poms.....
Only car that "let me down" was a '74 P6B when a bottom end bearing let go.
Oh!... and the Type 3 VW engine that fell out :lol: Cracked it engine mounts!

Currently the '98 Rodeo may break the RR record(but I ain't counting my chickens yet!) @ 400,000klms and hasn't missed a beat, except for valve recession(on gas)......

...BUT!! It aint a Rangie (or any other LR!!) and it can be disposed of without teary farewells!

As you only had it a week, and it's a '99 model...well who knows what the previous owner has done???

I should really learn how to pull apart/put back together a Rover V8!
Not that the skill would have come in handy! :rolleyes:

[Disco_Harvs]

Thanks for that Guys.

I'd be lying if I said it was the answer I wanted to hear, but thems the breaks. I'll be off to the wrecker for some new bolts this coming weekend. I've been quoted around $150 for a new set of bolts and if that's the price for not having to do this job again for a very long time, then so be it. Before this job the most complicated engine bay I'd worked in was a gemini's and lets just say the Disco has been a big step forward. There have been a few choice words said as I've tried to work in what seems to me, to be a tight engine bay. But at the end of the day, now that things are starting to work out, I'm glad I've attempted the job as I've learnt a lot. Mind you if I ever get stuck out bush I think I'd starve to death before I managed to actually get anything fixed. :)

Cheers,

Harvs.

[4bee]

Mind you if I ever get stuck out bush I think I'd starve to death before I managed to actually get anything fixed. :)

:D:D:D:D :rolleyes:

[amshaw]

Thanks for that Guys.

I'd be lying if I said it was the answer I wanted to hear, but thems the breaks. I'll be off to the wrecker for some new bolts this coming weekend. I've been quoted around $150 for a new set of bolts and if that's the price for not having to do this job again for a very long time, then so be it. Before this job the most complicated engine bay I'd worked in was a gemini's and lets just say the Disco has been a big step forward. There have been a few choice words said as I've tried to work in what seems to me, to be a tight engine bay. But at the end of the day, now that things are starting to work out, I'm glad I've attempted the job as I've learnt a lot. Mind you if I ever get stuck out bush I think I'd starve to death before I managed to actually get anything fixed. :)

Cheers,

Harvs.

Well harvs...how is it going??

[Disco_Harvs]

Hi amshaw,

I think it's all fixed. I put on the last few parts on the weekend and so far so good. I've only driven it once and I lost a bit of coolant but I'm hoping that was just air bubbles sorting themselves out. I'll be checking it again tonight any hopefully everything is fine.

I have a slight problem with idle, ie it won't idle at anything below 1200 rpm in gear and 1700 in neutral or park. I looked in the manual for a idle learning procedure for the ECU, but there doesn't seem to be one. There seems to be the idle control screw which modifies the revs a little but not much at all. Initially I thought it might be the throttle position sensor but that doesn't seem to have any impact on idle revs. I think I might just take it to the mechanic for a good tuning.

Thanks for your help everyone.

Harvs.

P.S. I didn't have any parts left over so that's always a good thing. Sure I lost a little scraper thing somewhere in the engine bay and still haven't found it but as there are no nasty clashing sounds I'm guessing it's not causing any trouble

[PhilipA]

Harvs,
The idle is set as "base idle" on the screw on top of the throttle body , then the stepper contols it at about 800RPM no load, and 550-600 in drive
If it is idling fast you have one of a few problems
1 There is dirt around the throttle plate. Fix, go in there with some carb cleaner and a rag.
2 You have a vacuum leak. Did you reconnect the little hose at he back to the fuel pressure regulator?
3 The stepper motor is sticking. Remove and clean the little cone thing with carb cleaner and clean the housing with cotton buds.(just like you do your ears) Assuming a 3.9 which I cannot remember.
4 You have the timing too far advanced. Check with a timing light.OR the centrifugal advance may have feozen. If a 3.9.

To set the base idle warm it up. Disconnect and block both ends of the hose from the manifold to the stepper and set the base idle to 550RPM by turning teh screw in or out. This is after youy have checked the other things.
Regard sPhilip A

[Disco_Harvs]

Thanks PhilipA,

1. When you say throttle plate are you talking of the whole accelerator etc assembly attatched to the plenum? If so I've sprayed that with CRC and wiped with a rag as I was worried some of the components may be sticking.

2. I have attached that little pipe but I did notice the other night when I killed the engine that there was a slight hiss coming from that area. I might need to investigate this further and ensure there are no leaks.

3. I never removed the stepper motor so I'm assuming it's still ok. If all else fails I'll check it out.

4. Again I'm assuming the timing is ok. I didn't touch any of the timing gear so it shouldn't be out. I hope.

"Disconnect and block both ends of the hose from the manifold to the stepper and set the base idle to 550RPM ". Damn it, I knew there was something I was forgetting last night. I'll block the hoses tonight and try again. :oops2:


Cheers,

Harvs.

[barney]

Thanks PhilipA,

1. When you say throttle plate are you talking of the whole accelerator etc assembly attatched to the plenum? If so I've sprayed that with CRC and wiped with a rag as I was worried some of the components may be sticking.

2. I have attached that little pipe but I did notice the other night when I killed the engine that there was a slight hiss coming from that area. I might need to investigate this further and ensure there are no leaks.

3. I never removed the stepper motor so I'm assuming it's still ok. If all else fails I'll check it out.

4. Again I'm assuming the timing is ok. I didn't touch any of the timing gear so it shouldn't be out. I hope.

"Disconnect and block both ends of the hose from the manifold to the stepper and set the base idle to 550RPM ". Damn it, I knew there was something I was forgetting last night. I'll block the hoses tonight and try again. :oops2:


Cheers,

Harvs.
should check your timing before you stuff up any idle or mixture settings. never assume it's ok...always check it. a lot of electricians have died that way

[PhilipA]

The throttle plate "butterfly" is the thing that turns inside the mouth of the throttle body. Also the pipe that comes from the ventilator into the plenum should be cleaned.
Sometimes you can also get a vacuum leak if the little T piece from that vent pipe to the bottom front of the plenum has cracked. This is not a normal Tpiece as it has a restrictor in it. Sometimes people replace this T piece with a normal T piece and they can never get the idle down.
Anyway , you now know where to look so go through each thing progressively.
Re the timing. You were able to remove the heads without pulling out the distributor? Good one. You can do mine next.
Regards Philip A