Can anybody help please?.
I had a new head gasket fitted to the above car in Jan 1999.
After 12000 miles the repair has failed and has to be done again.
I have discovered that the head was not skimmed during the initial repair and I thought that an alluminium head should always be machined before being refitted, otherwise premature failiure can result.Am I right please. Regards Cabman
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I thought that an alluminium head should always be machined before being refitted,
Only if it didn't meet the correct manufacturers tollerances.
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cabman
Dave's right, but head gasket failure is usually accompanied, by, or preceded by, engine overheating. This often distorts aluminium heads, which are more prone to damage than cast iron.
Hence the common advice to 'always' skim the head just to be on the safe side. Certainly get it at least checked for flatness if not skimmed before replacing the gasket again, and don't forget to recheck the head bolts for tightness after a 1000 miles or so, assuming they are not stretch bolts.
Also check the block face for damage, as the problem may not lie with the head.
Regards
John S
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cabman Dave's right, but head gasket failure is usually accompanied, by, or preceded by, engine overheating.
Did you establish the cause of the first failure. If the engine is persistently running hot, and I guess the AX has no temp guage, just a warning light, then it will go on eating head gaskets. I learned this lesson the expensive way with a Pug 104ZS 20 years ago.
Cheers
simon
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Simon,thanks for your help. I must admit I'm at a loss as to why the gasket has failed again,this will be the third time it has been replaced.Not bad for a car with 36000 on the clock, the first two times it was done under warranty (now expired)It has never overheatedand I'm just hoping that by proving that the job wasn't done properly before I can avoid a hefty bill.
Cheers Cabman
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It's very important of course, especially with an aluminium head, that the correct tightening procedure is followed otherwise further gasket failure can result.
Do you know why the gasket failed in the first place? If it was due to corrosion of the head, or misalignment of the coolant passages or combustion chambers due to a bad casting in the first place, simply replacing the gasket will not give a long term cure. What I mean is, the gasket could be failing because there isn't the correct width of land around one or more combustion chambers. The fact that the gasket has failed three times does suggest that there is some sort of a flaw in the head.
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Cabman,
Head gasket failure on a replaced head can be due to overheating, warped head, block faults (rare), poor quality gasket, failure to replace head bolts, poor torque procedure, lack of coolant changes etc.
Heads can warp but I think they warp less than folks think. There is a machine shop around here that will shave a load off every head they see without checking, "got to do it they say or it will just go again". There are some very high compression cars going about the Fens with their own problems!!
I always check the head and in personal experience find only perhaps 30% of them are warped and needing skimming. I can't think I've ever had to redo a head job....care at every stage is the answer.
I always say I'd rather have an engine at 150K that's never had the gasket done and look after it, rather than one that's had a new gasket that may or may not have been done properly.
Many engines go to the breakers without ever needing the head off, that is the norm.
David W
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the first two times it was done under warranty
Not sure if it's a myth or not, but I heard that garages don't get paid the same labour rate when the work is done under warranty as they would if the customer were paying himself. IMHO, if they don't get as much revenue for the repair, then less attention to detail can happen because they rush the job.
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Interesting therory Dave and highly believeable.You sound as cynical as me! Ive taken some legal advice from a well known motoring org.and they think I have a good case. Let You know.
Thanks
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I know D W is the man to explain this . The topping up of water and bleeding of air from this system is a bit more involved than most cars and if it is not done correctly could cause the problems that you have been unlucky enough to suffer. I believe the top of the radiator is lower than the top of the engine which is why the system should be filled via a home made header tank. I am not an expert DW is.
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