Sealer for cylinder head and crankcase gasket

[bob-d]

Should I use OMC sealer in the can or is there something newer and better?
What about the copper rings on the cylinder head gasket. Leave them dry?
Thanks.

[frankr]

Use OMC gasket sealer on the head gasket unless it comes with factory supplied sealant. Yeah, I know, early models said to apply them dry (or just didn’t mention it). Using it is better though. Crankcase gets Scotch 847 or gel seal.

[chris-p]

I know that the 3M 847 is the recommended sealer per the manual, but I am not a big fan of it for crankcase halves.

For gearcases yes, powerheads no, just my humble opinion.

It has fillers in it, and is not anaerobic. It hardens and dries before you get the halves closed, causing leaks. Loctite 515 , or better yet, Loctite 518 is ideal. Or as stated, the OMC Gel Seal.

[bob-d]

Sorry for my poor description. The gasket I’m looking to seal is the one under the crankcase between the exhaust housing.

[fisherman6]

That’s the powerhead base gasket. I typically install those dry. A sealer can be used, but I have found it isn’t necessary in my experience and it makes clean up next time a little more difficult. If I have one I think I may remove a few times, I have put a light film of grease on both sides so it releases. I haven’t had much of an issue with leakage with them. I’m sure others will offer their experiences and methods as well.
-Ben

OldJohnnyRude on YouTube

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