Replacing exhaust manifold gaskets

Bills money pit · 10-28-07, 10:24 AM

I have a exhaust manifold leak which can be heard when accelarating. I intend to replace the gaskets and upon trying to loosen the stud nuts, they are rusted to the bolts as one. Any ideas on how to loosen each one without breaking them off. Thanks for the help.
Bill...

fine69 · 10-28-07, 01:09 PM

Try saturating it with PB Blaster penetrating oil. I would spray the bolts several times within a 36 hours period... hopefully that will help unfreeze the nuts.

BarryK · 10-28-07, 02:27 PM

stock exhaust manifolds don't have gaskets to replace........

Bills money pit · 10-28-07, 08:19 PM

what type of sealer will stop the leak?

BarryK · 10-28-07, 08:59 PM

are you sure the exhaust leak is coming from where the exhaust manifold mates to the head? More likely is that it may be coming from one of the A.I.R. pipe connections in the manifold or elsewhere as the stock manifold is pretty thick and not very prone to warping on the mounting surface. If you are positive that is the location of the leak a local machine shop should be able to mill the manifold true for you.
I've never looked so don't really know if anyone offers a gasket for a stock manifold. Using a gasket solely to help "seal" a leak where a gasket was never originally intended to be you are using a bandaid approach to solving the problem rather than doing it correctly.

Vetsvette2002 · 10-29-07, 01:17 PM

Quote:

Originally Posted by Bills money pit

I have a exhaust manifold leak which can be heard when accelarating. I intend to replace the gaskets and upon trying to loosen the stud nuts, they are rusted to the bolts as one. Any ideas on how to loosen each one without breaking them off. Thanks for the help.
Bill...

Unless you are refering to the 2" dia. round gaskets, there were NO gaskets used between the exhaust manifold and the cylinder head.

To replace the 2" donut gaskets, apply either PB Blaster or Kroil and allow time to penetrate. Then try tightening first, another application of penetrant then loosen and remove the 3 front exhaust pipe to exhaust manifold retaining nuts.
Remove old gaskets and replace with new ones.
Re-install the retaining nuts and torque to spec (called out in the AIM).

Don

Bills money pit · 11-01-07, 07:39 PM

Thanks for the replys. Now I am not sure where the leak is located. A mechanic friend told me it was the manifold gaskets. Apparently he did not know there we no gaskets between the manifold and head. The leak is minor as I only hear it when I give it the gas and then it is faint. Maybe I should just turn up the radio and leave it alone. I always want the car to be perfect. It is that kind of vette, as orginal as any I have seen around these parts.

red70vette · 11-02-07, 05:16 PM

I would be wary of advice from your mechanic who thinks there is an exhaust manifold gasket leak when there is no manifold gasket. It tells me that he is like many other mechanics who are parts changers and have no diagnostic skills. They will continue to change parts until they get it fixed or you run out of money whichever comes first.

bradfordsvettes · 11-02-07, 05:38 PM

there are gaskets out there you can use .From the factory no gaskets were used but over time and with exhaust leaks ,rust etc

a gasket may be a band-aid for an irregular surface I have used the aluminum and copper with good results they are one piece the paper and metal ones do not hold up . At best it is still a stop gap repair

Steve

Bob Chadwick · 11-02-07, 10:39 PM

Quote:

Originally Posted by bradfordsvettes

there are gaskets out there you can use .From the factory no gaskets were used but over time and with exhaust leaks ,rust etc

a gasket may be a band-aid for an irregular surface I have used the aluminum and copper with good results they are one piece the paper and metal ones do not hold up . At best it is still a stop gap repair

Steve

X2. There were no gaskets there to start with, though they are commonly used to repair a leak. I had a leak problem with my exhaust manifolds, before headers, and one was solved at the metal shop and the other still required a gasket.

daveintexas · 11-04-07, 01:43 AM

There is also the possibilty that the manifold could have a small crack, and THAT is where you hear the leak coming from. They are made of cast iron, however they DO crack! Check on the bottom side or even on the inside next to the engine and see if maybe it has a very small crack in it.

bill81vette · 11-04-07, 07:35 AM

I too had an exhaust leak but only when I started the vette,after a few minutes it would go away.Last winter I found the leak to be where the exhaust pipe meet the manifold on the right side.there is a valve there for the emissions.I could take the flange and wiggle it when the engine was cold.

so under the vette I go with a socket and a ratchet and proceeded to break all three studs,even though I had used PB for a few days prior,off comes the manifold,drilled tapped and replaced all three with new studs and nuts.
put it back together and found the other side had a slight leak as well!!!

prepared to break those three but got lucky and the tightened right up without breaking

I did put new manifold gaskets on the right side.
and no more leaks!!