Re: Pros and cons on exhaust manifold sealant

Posted by Owen_Dyneto On 2015/12/9 15:26:24

Do not use sealant on manifold gaskets. Stop and think about it for a minute - the exhaust manifold gets much hotter than the engine block and thus expands to a greater length when hot than the block does; thus there is an ever-so-minute movement of the manifold against the gasket surfaces especially at the extreme ends as the engine heats up and cools down so a sealant is not appropriate. For this same reason torque of the manifold fasteners is important.

If you had the manifold surfaces, both intake and exhaust, surface planed as an assembled unit then you can bolt it directly to the block as as a unit. If you did not, then best practice is to loosen the hot box bolts, attach the manifolds, and then tighten the hot box bolts.