Lower Intake Manifold Gasket: Plastic Frame vs. Medal Frame on 1995 Chevrolet Lumina

I am replacing my Chevy 95 3.1L Lumina-sedan's lower intake manifold gasket, without push rod guides (1st design). There are two types for after-market products: Victor Reinz's plastic(body)+rubber vs. Dorman's metal(body)+rubber. Which one is better against coolant+engine oil leaks? Thank you. PS: Dorman's frame design looks different though!!!

by in Moorpark, CA on June 17, 2013
1 answer 7 comments
ANSWER by on June 20, 2013
Do yourself a favor and buy the gasket from the dealer. If the job is done right, the redesigned gaskets won't have to be changed again. You will have to remove and reinstall the pushrods though.
COMMENT by on June 20, 2013
Thank you for your advice. May I ask you how long it will take to do this changing lower intake gasket, cleaning the intake manifold, heads, and engine block's ridges for RTV sealants, for one person? does it require two persons?
COMMENT by on June 22, 2013
It is generally a 4-6 hour job depending on where you go and who is doing it. It is a 1 person job (normally). You will also need to pull the valve covers to remove the pushrods (unless you have the special tool that is designed to get them out without removing the valve covers) because you will have to loosen the rocker arms. Do not remove the rocker arms. BE AWARE THAT THE PUSHRODS ARE DIFFERENT LENGTHS AND DON'T MIX THEM UP WHEN PUTTING IT BACK TOGETHER. THE SHORT RODS GO TO THE ROCKER ARMS THAT ARE SET FORWARD IN THE HEADS (the intake valves), AND THE LONGER ONES GO TO THE ROCKER ARMS THAT ARE SET BACK IN THE HEADS (the exhaust valves). If you mix them up during assembly and start the engine with them in the wrong places, you will cause extensive internal engine damage (valves, pistons, or both).
COMMENT by on June 25, 2013
Great advice about the push rods, Thanks! Looking at the picture of intake manifold gasket installed on the engine, I think I only have to remove the intake valve, shorter push rods; in order to replace the gaskets. So, 6 short push rods removing, no sweat!!! Lastly, may I ask which is better to clean dirty block, manifold and heads for RTV, break cleaner or carburator cleaner? thank in advance.
COMMENT by on June 26, 2013
Neither. A gasket scraper is the best removal tool. Then wipe everything down with a shop towel with some brake cleaner sprayed on it to remove any residues.
COMMENT by on July 01, 2013
Thank you for your advice. However, upon reviewing instructions for installing lower manifold gasket and another manual, I am not sure what the thickness of RTV for sealing the ridges between the two cylinder heads should be. The instructions just mention 8mm-10mm beads of RTV for 3.1L V6 GM; is it for the width of RTV beads, of for the thickness of RTV beads or both? Please advice.
COMMENT by on July 03, 2013
Both. What we generally do is put a bit of RTV on the intake side, smear it on with a finger, then do the same for the engine block side. Both of these coats should be very thin. Then dab a bit of RTV at the corners of the Cylinder heads where the gaskets make contact with the engine block. A 1/4 inch drop will do you. If the new gasket kit comes with the rubber gaskets for the ends of the intake, you don't need any more RTV than what you put on with your fingers already. If it didn't come with the rubber gaskets, then run a 6-8mm(high and wide) bead of RTV along the engine block between the gasket corners. Just be sure if you have to seal the ends with RTV w/o rubber gaskets, that you set the intake down straight into place and don't move it around front to back very much.
COMMENT by on July 03, 2013
Thank you for your advice. Have a nice 4th of July!