1989 125 HP force L drive exhaust manifold question

[hornetswarm]

I am toying with the idea to use a high temp sealant on the exhuase gaskets. The gasket is a 3 part assembly, 1 alluminum gasket and two rubber gaskets. The manual does not state to use any sealant, but can it hurt?

The mating surface is in ok condition with a little chips here and there on the inner edges (looks like minor corrosion).

Anyone second the idea of using a high temp gasket sealant here.....

[pnwboat]

I've used Permatex Ultra Grey with good success on the exhaust gaskets. Don't over do it, just a light coating. Make sure you wipe the sealing surfaces off real good with some carb cleaner or similar product to remove any oil or grease residue.

[hornetswarm]

Thanks for the info. When I apply the Permatex, should I apply to the bare metal surfaces on the Powerhead and the exhaust mainfold....or right on the gasket?

[pnwboat]

After cleaning the metal sealing surfaces with carb cleaner, apply a light coating to both the gasket and the cover and block. Remember, the gasket was designed to work without any sealant. You're just adding a second layer of sealant to compensate for any irregularities in the metal sealing surface. You don't want too much of the sealant to squeeze out and restrict the water passages or break off and do the same. Once you bolt everything together, let it set up for a couple of hours at 70° for a couple of hours before you fire it up. The colder the temperature, the longer it takes to set up.

[hornetswarm]

PNWBOAT,

I appreciate the assistance. I will post some pictures of the project in work to assist future boat mechanics.

[hornetswarm]

Okay PNWBOAT. My gasket should come in the mail today or tomorrow. I have another simple questions hopefully. I want to replace the 20 or so bolts on the exhaust cover. I went to home depot and got zinc bolts that are the same size 1/4 (20) x 3 1/2. My only concern is they are zinc (standard grade fastners). Will these hold up?