Brown Substance on Flywheel Cover?

clutch dust and muddy water maybe

 

Does it smell like oil? Feel oily?

 

I would agree with clutch dust. The big question is, what is it wet with?

Coolant? Diesel oil is ussually darker or toward black so it doesnt look to be engine oil. Water is a possibility but the combination of engine, trans and clutch heat should keep everyting dry for a truck under normal on hwy use.

The other possiblity is trans oil?

Hydraulic clutch? Brake fluid?

 

Was the truck owned by a Chicago outfit before you bought it. One with a trap door under the driver seat?

 

I was thinking more along the lines of a weep from the input shaft. Looks a little too juicy to be seperating grease from overgreasing the release bearing.

 

clutch dust plus grease from bearing...

 

It just looks like it has/not been cleaned for a long time and grease from throw out bearing over a long of not pressure washed under truck, trucks with side panels make it hard to clean under trans. take a bent screw driver and scrap out what you can get out of bottom of bell/housing, don't shoot cleaner on pressure plate that can get in springs and make plates slip?