Did 7.4l engines not have an exhaust manifold gasket from factory?

[bob850]

I have a 1993 K2500 Suburban with the 7.4l engine, approx 113k miles. I asked a shop to replace the donut gaskets at the manifold to y-pipe connection. They managed to break the flange at the end of the driver side manifold, necessitating a manifold replacement. After what they did, I did not trust them so I just took the truck home.

So, I decided to replace the driver side exhaust manifold myself. When I got the manifold off, I saw that there was no existing gasket between the head and the manifold. I bought the vehicle used, but it appeared the manifold had never been removed before.

Did these engines not come with a gasket from the factory? When I installed the new manifold, I used an AC Delco metal gasket, and all is well now. But I'm curious about the lack of gasket on the old unit.

 

[someotherguy]

Pretty typical for them to not have gaskets from factory original. The machined surfaces are a nice match when new..

Richard

 

[Schurkey]

And the exhaust manifold stays cooler when not insulated from the cylinder head by a gasket.

 

[CrustyJunker]

Interesting to know big blocks were built like this. My small blocks were like this too, never leaked when reassembled either!

 

[Schurkey]

Interesting to know big blocks were built like this. My small blocks were like this too, never leaked when reassembled either!

Most old engines were built like that. Pontiac tended to use a gasket; I'm thinking that they were the only ones of the five sisters.

 

[Jason Glover]

If we have a leak from the matching surface (which I do on both driver and passenger sides) should buy a gasket set or look at getting the manifolds resurfaced?

 

[LC2NLS6]

My 93's 454s both did not from the factory. However, I replaced my manifolds on the one and I did use gaskets. My 87 V6 Turbo Buicks had no gaskets from the factory either.

 

[Schurkey]

If we have a leak from the matching surface (which I do on both driver and passenger sides) should buy a gasket set or look at getting the manifolds resurfaced?

You should INSPECT the manifolds for A) Flatness, and B) Smoothness.

IF (big IF) the manifold surface is warped, or if it's pitted/rough, sure, you're going to get it planed at a machine shop so that it's flat and smooth.

It's POSSIBLE--but not likely--that the cylinder head itself is pitted or warped.

And make sure the manifold isn't cracked, the bolts are the right length, and the bolt holes in the head aren't damaged.

You could reinstall with a gasket. Lots of folks do. I think it's a mistake. The gasket becomes an insulator, heat in the manifold doesn't transfer to the cylinder head, and so the manifold runs hotter than it would without the gasket.

 

[Erin]

And the exhaust manifold stays cooler when not insulated from the cylinder head by a gasket.

The exhaust guy I use doesn’t like using gaskets either. He’s uses some type of red silicone.

 

[Erik the Awful]

When I put my homemade headers on my Cadillac motor, I used copper RTV instead of gaskets. It worked great, even with the header flanges warped as hell. Goop 'em up and torque 'em down!