Tappet Cover and

[Iron Duke II]

The tappet cover on the '96 12V started leaking at sustained pressure during a test drive towing our small Nomad 5th wheel trailer. Lost about a quart on the 84 mile round trip. The leak appears to be coming from above the vacuum pump.
If it is the tappet gasket, is there a preferred brand of gasket that is an improvement over the OEM Cummins version?

 

[BigPapa]

Several threads on this..

https://www.turbodieselregister.com/threads/tappet-cover-the-right-stuff

https://www.turbodieselregister.com/threads/uh-oh-looks-like-the-vp44-gave-it-up

https://www.turbodieselregister.com/threads/oil-leak

 

[Cummins12V98]

Whatever gasket you use I would apply a bead of the "RiteStuff" to BOTH sides of the gasket.

 

[Chief USA]

This is another option albeit a pricier option but these tappet covers employ an o-ring seal and look pretty nice to boot. They are out of stock at the moment but hopefully will have more soon. I put one of these on the wife's truck when I had Bosch 275 RV injectors installed and the cylinder head & gasket rebuild done.

https://bdpshop.com/bean-machine-89-02-cummins-billet-tappet-cover-temporarily-out-of-stock/

Power Driven Diesel has a similar billet cover but does not use a true o-ring but I think it would seal much better than the OEM stuff.

https://powerdrivendiesel.com/product/pdd-billet-tappet-cover/

 

[Iron Duke II]

Which color Rightstuff is recommended, black or gray?

 

[Cummins12V98]

I like the Black. Never had a leak using it!

 

[BigPapa]

Did you read the other threads? There were several other suggestions and advice.

Personally, I’ve had success using the yellow 3M Weatherstip Adhesive to “glue” the gasket to the cover, let it sit overnight, then install the cover dry.

 

[Iron Duke II]

Sorry folks. I am experiencing medical issues and was unable to get to this myself. So the truck was taken into the shop that has performed some maintenance for us over the years. It appears after further investigation the leak was coming for a loose bolt on the rear of the p-pump. The fix cost $90, labor only. Thanks