Head Gasket - more woe

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David.Cox
Posts: 42
Joined: 21 Apr 2001, 13:49

Head Gasket - more woe

Post by David.Cox » 18 May 2003, 00:11

Car is BX 17 Diesel Turbo.
Story so far. four months ago engine replaced by local garage ( of normally good repute - they do classic restorations) with engine from reputable dismantler, with said to be genuine 60k use. At the same time my original rotodiesel pump was rebuilt by lucas. The replacement secondhadn engine looked on esxterior observation to be in good nick.
Two week ago appeared that head gasket had gone. Garage did test on the water header tank and confirmed it as head gasket. They did the head gasket, but observed when I picked it up that there had ben "slight corrossion around the water ports - cleaned up, head skimmed and ok to fit." In addition, when they first tested the car after doign the gasket they found the metal water "bypass pipe" to be corroded to the extent that it was leaking so they replaced it.[:)]
Took the car out following day, and had white smoke once again coming out. Garage looked at it again - I had thought perhaps we had a turbo problem, as I could not hear it whine, like it used to. They took it for a drive and said nothing was wrong.
I took it back and in driving 40 miles had to top up water every 20.At the end fo the d rive the water in header takn was agitated, if not boiling, and an hour later there was considerable pressure as I took the cap off
With engine stone cold this morning I did the head test e.g. run engine for 30 seconds, and found there was pressure, all pointing to head gasket again.
This almost immediate failure makes me wonder if we are talking head gasket at all. DAvid Burns in a previous posting 24/1/03 talked about possiblity, albeit uncommon, of cracked block/head to water jacket as anotehr possibility, though he was talkign about this in a different context. It is the corrosiion business, which makes me wonder about there being something other than the head gasket which is joining the water system to the engine gasses, and hence the possibility that the engine is totally US as a result.
Advice would be much appreciated.

jeremy
Posts: 3959
Joined: 20 Oct 2002, 16:00

Post by jeremy » 18 May 2003, 14:21

The citroen TD engine is prone to head cracking, even though it is made of a different alloy to the normal one. Often these cracks are very small and they open up when the head cools, and close when it warms up.
One would like to think that a good mechanic would test it for cracks when changing the gasket!
corroded waterways could cause this problem but I would have expected failure after a little while not immediately.
jeremy

David.Cox
Posts: 42
Joined: 21 Apr 2001, 13:49

Post by David.Cox » 18 May 2003, 16:38

Thanks jeremy. What concerns me is whether the original failure was not in fact the head gasket. I have the discarded gasket . Would it show signs of having failed ? Or ws it f rom the start a leak between water jacket and engine.?
The mere fact that there is some corrosion for sure in the waterways makes me wonder if this was the problem to start, and by the time the head has been removed and looked at we might as well have put another engine in in terms of laboour costs ! I am thinking in terms of biting the bullett and getting a fully recon engine, and persuading the garage to spend the labour time on putting recon engine in rather than messing with the present one. Does anybody agree that this might be the best policy.

jeremy
Posts: 3959
Joined: 20 Oct 2002, 16:00

Post by jeremy » 18 May 2003, 19:04

I should have explained that the corrosion I think is being referred to is corrosion of the alloy head around the waterways. This is common with alloy heads and generally means that the edge of the waterway recedes a little and the contact is with the wrong part of the gasket - causing leaks. These can be cured by welding a new edge in place and machining the face again.
Blocks almost never corrode significantly and the chances of a bore having rusted through is most unlikely. Cracks - well I suppose its possible but most cracks happen in the outer water jacket rather than the bore itself.
Not many otherways in which the cooling system can become pressurised unless it is boiling because of air locks or water pump problems. If it was waterpump you wouldn't get steam in the exhaust.
This may just be bad luck for the mechanics who did the job and the gasket itself is defective but I'm sure thats where the problem is.
Jeremy

David.Cox
Posts: 42
Joined: 21 Apr 2001, 13:49

Post by David.Cox » 19 May 2003, 03:41

Thanks Jeremy. I had read it slightly wrong. Looks like recon head at most then.Put my mind at rest quite a bit. I was beginning to wonder about the block rusting through - especially with a comparatively young engine.

jeremy
Posts: 3959
Joined: 20 Oct 2002, 16:00

Post by jeremy » 19 May 2003, 04:14

I'm still concerned that the gasket appears to have failed so soon. It may be worth having a good look at the old gasket and seeing if you can work out what may have happened (not always as easy as it sounds!)
I have never fitted a head gasket on these engines but understand that getting the gasket in the correct place is far from easy due to the angle of the block etc. There have been some posts here dealing with this problem. I wonder if the gasket itself was damaged accidentally during fitting or if possibly the head has not been torqued down properly (itself a complicated process. Other possibilities could be the use of incorrect bolts or re-use of old and stretched bolts. I do not know how much spare thread there is under a properly tightened bolt but believe that for example the heads of later diesel engines are thicker to prevent cracking - it may be that longer bolts are used for these heads . . .
Speculation - I know.
This reminds me of fitting another engine in a mini for my wife. I thought I'd make a good and smart job of it and decided to paint the engine before I fitted the engine. I duly cleaned the thing up and put on my new gasket, fitted the head and tightened it up finger tight before painting it. I then fitted the engine and torqued up the head, then went to start it. - No life at all - and apparently no compression! - well - inevietably I had to remove the head again and there was the problem - the paint had gone into the head joint and formed a small lump of solid paint along the edge of the gasket - thick enough to prevent the head seating properly!
jeremy

David.Cox
Posts: 42
Joined: 21 Apr 2001, 13:49

Post by David.Cox » 20 May 2003, 03:46

Thanks again Jeremy. Garage has been a star. They would not have made mistakes in fitting, and certainly used new headbolts etc. this is a garage that restores lots of old cars. They have accepted that the head is probably cracked. time taken to replace with a recon head, same as engine change ; hence we have come to mutual agreement that they put me back in the position I was when we decided to put secondhand engine in. I am paying for a full recon engine, and they will fit it free of labour charge.
All I have to do is find the money, but my baby is really worth it and I will not have it die on me yet.
Thanks for the help