Re: Blown Head Gasket?

[Scott Fisher <sefisher@domain.elided>]

Karl Robrock asks about diagnosing a blown head gasket on his V6:

> First, I have no idea how to diagnose which head has a blown gasket 

Compression test *may* tell you, if the gasket has blown through around
the cylinder as well. It's at least a fairly easy test to perform; look
and see if one cylinder is seriously low compared to the other five, and
that's the head with the bad gasket.

> Also, I was wondering if while I have the head pulled I should
> do anyother work worth doing (anything related to cams, valves,
> etc.).

It's generally not a good idea to make major changes to one side of a
V-type engine without doing the other one as well.  The exceptions would
be to replace valve-stem seals if required, or of course to repair any
other obvious failures (e.g. a burned valve, flat cam lobe, etc.)  But
in general, it's not a good idea to do say a valve job on *one* head and
leave the other one alone -- it puts unequal stresses on the engine. 
(And there are even those who say you shouldn't do a valve job without
also doing rings, because the higher compression at the top end will
accelerate wear at the rings and can cause failure/blow-by that much
sooner.)

> Is there any reason I should NOT do this myself? I am assuming this
> would cost $600-$800 at a shop. I will however, have my car towed 
> to a shop to have the radiator flushed.

I don't get your logic here -- radiator-flushing is a driveway job,
pulling the head is much more involved.  I've never pulled the head on
an Alfa V6, but I've done a selection of British sports car
decapitations; the key to good head replacement is having a good torque
wrench, an excellent manual, and a lot of patience.  Even better is to
have someone beside you who's done the job before.

Best,

- --Scott Fisher
  Sunnyvale, CA

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