Intake gasket question

[maddog2]

I have a question concerning the aplication of the intake manifold gasket.

My engine is a 1992 Mercruiser 4.3LX with a 4 barrel Webber carb.

question: Does the gasket go on dry?

Do you apply gasket sealer to the intake gasket?

I know that the intake has only the water inlet on the front where the thermostat is located. The back side of the intake is blocked off.

 

[Bt Doctur]

Re: Intake gasket question

Personally, all my motors get "Permatex Aviation sealant" around the water jacket ports only,
When you install the manifold, use a good amount of Black RTV front and rear
but don`t tighten the manifold down all the way ,let sealant cure, then tighten to spec.

 

[tinman565]

Re: Intake gasket question

Personally..I put a thin coating of sealer around each port on both sides of the gasket. That way, I'm positive I'm not getting a vacuum leak. As the motor heat cycles (cold,hot,cold..etc)..the intake manifold bolts have a tendency over time to loosen up a bit. Everbody installs manifolds there own way, and in my opinion, a thin coat of sealer all around each port cant hurt.

 

[Gary H NC]

Re: Intake gasket question

The bead on the front and rear lip i put on a little heavy and overlap it onto the gasket about one inch.

 

[maddog2]

Re: Intake gasket question

I downloaded the Mercruiser service manual for this engine and it says to
(1) apply Perfect Seal to intake manifold gaskets and install gaskets on cylinder heads.
(2) place a 3/16" (5mm) wide bead of RTV sealer on block. Extend the bead 1/2" (13mm) up each gasket to seal corners.

The image in the manual shows the RTV sealer on the block and 1/2" on each corner. There is no mention of adding sealer around any water openings or intake/exhaust openings.

My problem is that the "backyard" mechanics calling themselves a boat repair center had silicone on both sides of the intake gasket. when I found water in the oil, I removed the intake and examined the gaskets. Im no specialists, but a friend showed me places on the gaskets where water was leaking into the engine. He says to only seal the block and the gasket corners as the service manual describes.

 

[tinman565]

Re: Intake gasket question

I'm just telling you what I do on my stuff. We run high horespower drag motors (blowers, nitrous, and naturally aspirated combos), we build and repair other peoples motors...and built, and maintain our 502 Mag motor in our boat. I have never had a problem with putting a thin coat of sealer on both sides of the intake gaskets. The problem with some peoples repairs is that they dont take the time to do a proper job...dont pay enough attention to detail..and or just dont give a sh*t about you as long as they get your money.
Clean the head surface PERFECTLY with a razor blade, or a small wire wheel on a die grinder..then wipe it down with a solvent and let dry. Do the same on the intake. Make sure they are both spotless. Apply a light coat of sealer around all the ports on the head, install the gasket..then apply a light coat of sealer around all the intake ports and assemble the intake to the head. Tighten the bolts in a circular direction starting from the middle and working your way out. After the motor has been run and cooled down a couple times, go back and re-torque the intake bolts again. You wont have a problem sir.

 

[maddog2]

Re: Intake gasket question

Thank you Tinman565 for your input and expertise on this subject.