Intake manifold leak

[MJRider]

My '96 GMC Suburban 5.7L Vortec has the routine intake manifold leak. I would like to replace the plastic manifold when I have it off with a cast one but have been having trouble finding a replacement that I am sure will fit.

Does anyone know of a replacement model that will fit this truck?

[kenny-1907]

I am not sure what exactally you are talking about. The intake manifold on ANY engine is either gonna be cast or aluminum. I had a 96 sierra with the 5.7 and if it is the same notorious leak that you are talking about , it is leaking from the rear intake manifold gasket, and if that is the same thing , it is aluminum not plastic and all you need to do or have done is replace the gaskets. I took mine in to have it done because it was the middle of winter and i did not have a garage to work in and cost me $400 to replace all the intake gaskets.

[skipr]

Originally Posted by kenny-1907

I am not sure what exactally you are talking about. The intake manifold on ANY engine is either gonna be cast or aluminum. I had a 96 sierra with the 5.7 and if it is the same notorious leak that you are talking about , it is leaking from the rear intake manifold gasket, and if that is the same thing , it is aluminum not plastic and all you need to do or have done is replace the gaskets. I took mine in to have it done because it was the middle of winter and i did not have a garage to work in and cost me $400 to replace all the intake gaskets.

Sorry, but you are mistaken. The upper manifold is mylar (a form of plastic) And I don't know if you can get one aluminum or cast. I changed out my intake gaskets myself, it cost $40 for the gaskets. But alot of labor involved taking offf all the stuff in the way of getting to the manifolds.

[kenny-1907]

Was this something different on engines that were made elsewerer ? ? I could have sworn that my intake was aluminum on my 96, and i just got off the phone with the garage that did the gaskets for me and they said that it was aluminum <shrugs>

I't's not like i have not been wrong before

[kenny-1907]

well , i just got off the phone with GM here and they said that there is 2 parts to that intake , upper and lower. The Acutall intake which is the lower part is aluminum but the upper part which the called the runners or the plenum (spelling) is plastic and that has nothigh to do with the leak <shrugs> I did not do the work my self as i said cause it was cold as hell when it happend of course

[skipr]

You are correct, about the lower being the source of the leak. But you have to take off the upper to get to the lower, and it would be foolish not to change the upper to lower gasket when putting back together.I guess you could call it a plenum, but the OEM service manual clearing states it as being the upper intake manifold, but no fuel goes through the upper intake so theoretically it's an air plenum.