I've searched the forum for upper oil pan sealant, and I understand that this is quite the controversial subject! I'm over the RTV controversy and I'm just going to overpay for the magical MB sealant from the dealer (part# 003 989 98 20 10) and eliminate any doubts.

My question now pertains to the proper application of this sealant. I can't seem find the answer online or in the FSM. Ignoring alignment issues at the front crank seal for now, what is the proper way to seal this junction?

Lay down a bead of sealant, then torque to spec?
Lay down a bead of sealant, snug up, let dry, then torque to spec?
Smear the sealant over the whole surface (let dry?), then torque to spec?
Any other combination of these techniques? Apply to one surface or both?

Thanks in advance for the help!

Anytime I've used sealant gaskets I have smeared the sealant, installed the part snugly, then torqued after it sets up a while.
Don't know if this is correct, just my way.

Auto repair shops don't do it this way. They are in a hurry. And their way seems to work also.

use non aerobic gasket sealer and smear,the blue and red sealants can get into engine and plug oil holes and such. I use the old fexible Form A Gasket.

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1999 w140, quit voting to old, and to old to fight, a god damned veteran, deutschland deutschland uber alles uber alles in der welt

Is the "magical MB sealant from the dealer (part# 003 989 98 20 10)" non-aerobic?

My vote is to make a bead. In my experience smearing just makes a mess and it is very difficult to produce an even amount of sealant over a large mating surface (when smearing).

My advice is to practice for a bit with a mastic gun and a tube of sealant first if necessary.

The aim of the game is to provide consistently wide and high beads of sealant (in relation to the width of the mating surface - see below) around each bolt hole and across the mating surface between. The pressure you apply to the two mating surfaces when tightning down will do the smearing for you! You have to do a bit of guessimation to make sure that you don't squash out too much sealant when joining the mating surfaces though. I usually aim to make a bead approximately one quarter of the width of the mating surface - that seems to have worked well for me so far.

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1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!