740 head gasket

  • Thread starter Thread starter Stewart Hargrave
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Stewart Hargrave

We've seen several 740 head gasket failures on this group recently.
Well, now it's my turn. I'm well familiar with the symptoms, and there
is no questin in my mind that my head gasket has failed too. The
question is why?

I replaced the gasket two and a half years ago, in which time I've
done less than 25k miles. I was meticulous with the job, and
everything was properly done, including skimming the head. There have
been no episodes of overheating since then, and I can think of no
other obvious reason why it should have failed again.

But I seem to remember a while ago someone (James?) saying that the
head bolts needed a further tightening sequence after the engine had
been through a heat cycle. Haynes implies specifically otherwise, so I
would be interested to hear more about this.

Anybody got any other comments to prevent this being a regular
occurence? Or just to make me feel better about things?
--

TSH


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Stewart Hargrave said:
We've seen several 740 head gasket failures on this group recently.
Well, now it's my turn. I'm well familiar with the symptoms, and there
is no questin in my mind that my head gasket has failed too. The
question is why?

I replaced the gasket two and a half years ago, in which time I've
done less than 25k miles. I was meticulous with the job, and
everything was properly done, including skimming the head. There have
been no episodes of overheating since then, and I can think of no
other obvious reason why it should have failed again.

But I seem to remember a while ago someone (James?) saying that the
head bolts needed a further tightening sequence after the engine had
been through a heat cycle. Haynes implies specifically otherwise, so I
would be interested to hear more about this.

Anybody got any other comments to prevent this being a regular
occurence? Or just to make me feel better about things?
Click to expand...


Depends on the type of bolts, the older rigid bolts with allen heads need to
be retorqued after a heat cycle, the newer stretch bolts don't, but should
be replaced when the head is removed. Supposedly you can reuse them once and
you might get away with more but it's not adviseable. As for why the gasket
failed, was the top of the block checked for flatness? Did you use a name
brand gasket, or some cheapie? Might have just been a dud part.
 
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