Sealants to use with cork sump gasket

Hi Folks

Just buttoning up a 3.8L V6 VN Commodore engine and have watched the relevant videos on sealants.

Sump had a neoprene/rubber type gasket fitted however the replacement bottom end gasket set is a cork sump gasket.

Question - what sort of sealant should be used with this? The manual makes no reference to sealant being required nor does it comment on gasket type. As cork gaskets quite often relax after torquing down what would you suggest?

I had thought of using Loctite Master Gasket 515 Flange sealant to both sides of gasket.

Any suggestions would be appreciated and also would you retorque a couple of days later once the gasket relaxes?

Cheers Mal

Biggest problem with sealing cork gaskets is overtightening the fasteners*, which both forces the cork out and distorts the sealing flange.

Others may do it differently, so bear that in mind, but my normal practice is to make sure the sump is flat, even slightly 'reverse dimple' the holes where the fasteners are, and use a thin bead of an oil resistant RTV type sealant on the sump flange and engine surfaces and assemble it, LIGHTLY (5-8 lbs.ft is a common figure) tightening the fasteners in a cross pattern, repeating it.

After a few weeks, I may LIGHTLY recheck for settling.

*Why most modern sump and rocker gaskets have metal inserts where the fasteners go, to make it impossible to over tighten them.

Thanks Gord for replying to my question it's appreciated. Since posting the question I got hold of a Loctite technical rep, who by the way was extremely helpful.

He said that the Loctite Mastergasket 515 flange sealant was their recommendation, they call it a gasket enhancer and suitable for cork.

Like you they said apply to sump flange and block. Apparently when the mating surfaces are bolted together the sealant cures due to lack of oxygen. If by chance any sealant goes into sump it doesn't cure so doesn't cause any potentially issues blocking a oil gallery.

The Gregorys manual recommends 12nm torque which aligns with your 8lb ft figure.

Motor will sit on engine stand whilst I detail engine bay so I will do as you mentioned and lightly recheck prior to installing.

Many thanks for sharing your knowledge.

Cheers Malcolm