To put sealant on gaskets or not-

Perchin 1

Cadet
Joined
Jan 29, 2010
Messages
12
Another question, I have a 1975 4hp evinrude that was running a bit hot so I pulled the cylinder head and exhaust plate and found a piece of rubber in there-anyway when putting the powerhead and exhaust plate back on should I put a a high temp sealant on the gaskets? Also should I flat sand the head? Thanx in advance-
 

Texasmark

Supreme Mariner
Joined
Dec 20, 2005
Messages
14,544
Re: To put sealant on gaskets or not-

Some do and some don't use it. I do and I don't; depends. Problem with sealant is that it is not your gasket and may provide less sealing protection than your gasket; course it could do better also.

I use Kopper Koat on my head gaskets and never had a problem, especially on automotive heads. I get it in the spray can and put a light coat on all surfaces and when tacky, put it together. It's made for heads.

I never use sealant on a carburetor.

Only problem I ever had with sealant was on auto tranny pans. I even bought aircraft quality sealant and it didn't work; didn't matter if the gasket was cork or rubber. What finally did work was sealant on one surface (both gasket and pan) to hold it in place, and nothing on the other (the tranny side). That worked.

On sanding the head, you need to be sure that the head is flat, as should be the cylinder mating surface. On sanding, you remove the corrosion protection so if I did it, I would come back with some Zinc Chromate spray and protect it prior to reassy. If I did the spray primer, I wouldn't use a sealant and I would not reassemble until the primer had time to dry.

My 2c,

Mark
 
Top