Re: 740 head gasket
"Stewart Hargrave" <SpamOnlyToHere@MiserableOldGit.Me.uk> wrote in message
> 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?
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.