Exhaust Leak On 396/425 Engine, 1965

[Daniel K.]

Good evening,



Thank you all for your help.

Dan K.

[William C.]

Re: Exhaust Leak On 396/425 Engine, 1965

GM did not use gaskets on the exhaust manifold to head surface. Take them all out and clean the surfaces of head and manifold, torque to spec and you should be ok.

[Daniel K.]

Re: Exhaust Leak On 396/425 Engine, 1965

Thank you Bill.

This engine does look like it has gaskets. Engine was rebuit in the late 70's or early 80's by Rick Race. I will take apart and clean, clean. clean.

Thanks again.

Dan K.

[Joe L.]

Re: Exhaust Leak On 396/425 Engine, 1965

Thank you Bill.

This engine does look like it has gaskets. Engine was rebuit in the late 70's or early 80's by Rick Race. I will take apart and clean, clean. clean.

Thanks again.

Dan K.

Dan-----


I expect the gaskets were installed when the engine was rebuilt. This is quite common as engine overhaul gasket sets usually contain the exhaust manifold gaskets even though they were never used in PRODUCTION.

After you remove the manifold and thoroughly clean the gasket surface, I would check it or have it checked with a precision straight edge. If it checks out as flat, simply reinstall without gaskets. If it does not check out, have the surface machined flat. Then, install without gaskets.

When exhaust gaskets are used on big blocks, they must be present on all 4 ports on each side. If one or more of the gaskets are removed and the others left in place, you WILL have a leak at the ports without the gaskets. It's "all 4 or nothing" on each side.

[Daniel K.]

Re: Exhaust Leak On 396/425 Engine, 1965

Thank you Joe for your help.

Dan K.