Finding exhaust manifold leaks

philip l. stewart

New member
Dec 16, 1997
287
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>
> I'm more concerned
> with the possibility that I have a leaking exhaust head. That sound comes and
> goes.

Richard, I once too was concerned that I thought I was hearing the start
of an exhaust manifold leak, but I remembered a technique that I saw a
savy mechanic use to pin point the location of such a leak. He used a
3' long piece of garden hose which he held to his ear while the engine
was running. The other end of the hose he ran along the mainfold and
head joint listening for the tell-tale puffing of a small leak.

When I did this same thing with my GMC I quickly located the cylinder's
exhaust port which was leaking. When I got the manifold off, the blow
by mark on the gasket was just where the hose said it would be.

There's a lot of noise inside the engine compartment and this method is
similar to using a stethescope for finding where the quieter ones are
coming from. I now use this method as part of my preventive maintenance
since I know that a small leak needs to be fixed before it gets large
enough to start damaging the heads.

As Arch would say, that's what I did.

Phil Stewart
'76 Transmode, TN
 
Thanks for the advice. I'll check that out as soon as I get the coach back here
again. It's still at the storage lot waiting for warm weather.

Richard Waters
'76 Palm Beach, Troy, MI

> >
> > I'm more concerned
> > with the possibility that I have a leaking exhaust head. That sound comes and
> > goes.
>
> Richard, I once too was concerned that I thought I was hearing the start
> of an exhaust manifold leak, but I remembered a technique that I saw a
> savy mechanic use to pin point the location of such a leak. He used a
> 3' long piece of garden hose which he held to his ear while the engine
> was running. The other end of the hose he ran along the mainfold and
> head joint listening for the tell-tale puffing of a small leak.
>
> When I did this same thing with my GMC I quickly located the cylinder's
> exhaust port which was leaking. When I got the manifold off, the blow
> by mark on the gasket was just where the hose said it would be.
>
> There's a lot of noise inside the engine compartment and this method is
> similar to using a stethescope for finding where the quieter ones are
> coming from. I now use this method as part of my preventive maintenance
> since I know that a small leak needs to be fixed before it gets large
> enough to start damaging the heads.
>
> As Arch would say, that's what I did.
>
> Phil Stewart
> '76 Transmode, TN