I took apart my melling high volume oil pump (m22fhv) for cleaning and inspection and noticed there wasn't a gasket on the cover. I see that there's a cover gasket included in the Mahle gasket set I have, but is it necessary? I had 60+ psi cold and 25 psi hot at idle without the gasket. Happy thanksgiving!

 

If you use the gasket, it will increase clearance between the rotors and the cover.

There will be an internal oil leak that you didn't have before and your pressure will drop.

 

Thanks for the explanation, it makes sense.

 

The gasket is for std volume pumps.