Just how difficult is a head gasket?

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Oscar
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Just how difficult is a head gasket?

Post by Oscar »

I had to put a litre of water in Groliffe this morning, and we blew out clouds of steam all the way down the M2 for 7 miles before I decided to turn back. How tricky is a head gasket? I mean, what are the wrinkles and tips that people can offer? I have the Haynes and the Russek, I'm looking for people's own experience - all contributions and pointers gratefully received.

Cheers

Oscar
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Post by themildbunch »

hi - looking at your profile I'm guessing this is a TZD that has blown? As you may have read my new TZD has a similar problem but not as obvious... I'm not going to attempt it, much as I'd like to, as I don't have the space or time and the pain of dealing with the turbo / exhaust manifold has put me off further...
Having said that I did take the head off my 16 valve when the cambelt snapped, replaced all the bent valves, put it back together and it fired first time! That really wasn't that difficult but I do verge on the obsessive when looking at manuals so I probably changed more and took much more time than was necessary - The one thing I did find tricky though for a novice was judging what was really worn, a little worn or fine...
My local specialist needs the car for 3 days to do a TZD head gasket - this includes time for the head to go off to a machine shop for a skim - around £600...
Another more positive way of looking at it is that you'll be getting a new cambelt fitted, oil and coolant changed and a nicely reconditioned head as well as the gasket if it's all been done properly!

You'll get great support here if you decide to DIY...
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Post by docchevron »

It's a tad more involved on a TD as opposed to the N/A but still easy enough..

I've taken to undoing the exhaust manifold and leaving it in situ before removing the head since removing the down pipe and turbo feed and return pipes can be a faff.

It's all pretty straightforward and well explained in the BOL really.

It's easier reassembly if you time and lock the engine before dismantling, and it pays to undo the 16mm bolt that holds the cam sprocket to the cam before removing the belt or locking the cam (since if you rely ont he locking bolt it'll more than likely tear out of the head).
You can of course remove the cam cover and use a spanner to hold the cam but I've never come across one yet that wont undo against compression by giving the spanner a good tap.

Don't forget the top bolt on the engine mount that screws into the head, mor than once I've cursed something chronic at a "stuck" head before remembering that bloody bolt...

It pays to clean the block face with some emery on a rubbing block..

Other than that, it's all pretty straight forward..

Good luck!
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Post by mat_fenwick »

docchevron wrote:Don't forget the top bolt on the engine mount that screws into the head, mor than once I've cursed something chronic at a "stuck" head before remembering that bloody bolt...
Or the top bolt on the cambelt tensioner! And a ratchet spanner is very helpful getting off the exhaust manifold nuts.
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Post by kiwi »

If you got the tools then not to difficult.

While you at it change the water pump as well.
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Post by KevR »

kiwi wrote:If you got the tools then not to difficult.

While you at it change the water pump as well.
Sound advice - water pumps are cheap and since they're a weak point, it's worth doing.

I seem to remember that there are various thicknesses of head gasket, and you have to wait 'til the head's off to measure how far the pistons come out of the block before you decide which one you need. I might have dreamed that though.
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Post by mat_fenwick »

No, that is correct. What most people seem to do is just fit the thickest gasket, identified with 3(?) notches at one end (the more notches, the thicker the HG). Most gasket sets simply come with the thickest gasket in anyway! Obviously this will drop the compression ratio slightly but not sure whether it makes a noticeable difference.
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Post by Oscar »

So the BOL is correct in the first part about proceeding as if I were doing a cambelt change? That's good to know. I've done that before and can change the pump and tensioner at the same time, as well as renew the coolant.

Nice to know too that it doesn't really matter if I fit the thinkest gasket. I'd rather buy all the kit, line it up and then start, instead of having to stop and go off and buy stuff - always takes 3x as long, in my experience.

Yes, it is a TZD that has gone.
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Post by mat_fenwick »

Oscar wrote:So the BOL is correct in the first part about proceeding as if I were doing a cambelt change?
Yep, once you've done that it's just a case of removing a few more bolts and the head's off. Simple as that!
I've only done one BX TurboD HG change, and a couple of other XUD changes so am not super experienced but would reckon on 4-5 hours to get everything apart (if I worked on it without interuptions) and the same again to get it back together. I always end up doing other jobs at the same time so the whole thing takes days/weeks!
You'll need a T55 Torx bit for the head bolts if you haven't got one already.
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Post by themildbunch »

Shouldn't the head mating face be checked for 'flatness'?
Isn't this why heads are often skimmed to be safe?
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Post by mat_fenwick »

Yes - if it has overheated (difficult to tell without a temperature gauge the head is likely to have warped. Some people will skim regardless but if the head is flat and the sealing surface is intact there is no need.
You need to find out the reason for the HG going in the first place unless you want to gain practice quickly...
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Post by docchevron »

I did three in a weekend once, all on the same car. I got the time to remove the head down to 28 minutes...

Personally I'd have the head skimmed, recut the valve seats etc etc, but if the head is flat then a clean up and refit should be fine..

If you do get it skimmed then you could specify to the machine shop that you want absolutley NO milling marks at all in the surface then use an all metal gasket.
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Post by Oscar »

I doubt it has overheated. The temp guage didn't go much past its normal parameters, so I think it's ok. As far as the cause of the failure is concerned - good question. Would "age" be reasonable? Do HGs just give up after a while?
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Post by Jaba »

Oscar,
What nobody has mentioned yet (I think) is that you have to detach the lower mount and swing the engine forward at the RHS to get at the stuff behind the head.

The head comes off easily enough but getting it back on by yourself can be tricky. I usually put it back on without the manifolds and studs, but just refitting the studs and manifolds takes longer than Doc's 28 minutes, so its not a time saver.

Here's a quote from Andyspares Forum in 2005 by Richard West that you might find helpful ( I would post the link but the thread has disappeared from the FCF)........

">3. Haynes tells me to put 8mm dowel/drill in flywheel hole to lock >#1&4 pistons at TDC - this is fine, but I can't even see the hole >behind the starter - do I need to remove the starter to do this and >is it a big job?
You should be able to do it without removing the starter - get a long piece of 8mm bar and bend about 100mm up to about 15°. The hole is just above the sump / block joint, and using a long rod allows you to stand by the RH front wheel, and slide the rod in whilst turning the engine over with the wheel.

>4. What size TORX socket is needed for the head bolts - are there >any other 'special' tools required?
T55 for the head bolts. You need a 16mm deep socket to get the engine mount off.

>5. Can I pull the head off with the intake/exhaust manifolds and >turbo attached - is there enough physical room. I don't want to try >and remove the manifolds in place if possible - I've got nightmares >about broken studs!

Yes, but it's tight! Remove the engine mount and prop the engine forward with a block of wood off the bulkhead to make more room. When refitting the head, use a piece of cardboard to protect the head / block first, then when it's in position, slide the head gasket in. Otherwise it gets wrecked

>6. Any other tricks/hints I should know about before I do this -

If your wallet can stand it, replace the three braided hoses that go down the back of the block. You don't want to be doing those the week afterwards... When reinstalling the head, make sure that the turbo oil feed goes the right side of the driveshaft before you torque the head down (experience again!). The left most 3 head bolts on the back of the head cannot be removed or fitted with the inlet manifold in place, so don't forget to fit them before you drop the head back on! Tie wrap them up to the manifold whilst you are putting the head on. "




I have got one to do as well - my head is cracked , down on power and and pressurises the coolant.
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Post by RichardW »

"Here's a quote from Andyspares Forum in 2005 by Richard West that you might find helpful ( I would post the link but the thread has disappeared from the FCF)........ "

:lol:

I hadn't even done a cambelt when I did that HG job way back in 2002. It would be a lot easier the second time. If you can remove the manifolds so much the better, but it was almost impossible to remove the centre bolt on the inlet manifold on mine even with the head on the bench, so it had to come out complete. It's 'kin heavy like that, so get an assisstant if you can!
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