Rear Main leaking 04 6.0 16k

[Mighty Hd]

I have had an oil leak that the dealer can not find now for months and months. It leaks on the ground in the driveway/garage and I have given up.

The truck has 16k on it, oil changed every 2k, M1 5w-30 or 5w-40. By the bible.

When we left for our 500 mile trip to our destination I cleaned underneath the truck and got all the oil off the bellhousing and oil pan. It was spotless. By the time we got there it was smoking from oil on the exhaust, and completely soaked underneath. Obviously there is a leak somewhere

Or there WAS.

The oil level stays just a pinch under total full with 6 quarts.

Once we got to the inlaws, I then again cleaned underneath the truck and got all the oil off, scrubbed everything down with a brush & degreaser. Yes I'm a bit anal.

The oil level just dropped a hair. Most people wouldn't notice it.

So the drive back -- 500 miles, 65-75mph, a few stops here and there.

I check once we get home and not a single drop of oil anywhere.


What gives?

[bud8fan]

shure it's not coming from your oil pan gasket around the back of the motor....

[RedHeartbeat]

Check the oil sending unit. The prestolite sometimes cracks during assembly and it doesn't get caught, or the engine bangs against something cracking the plastic-like top half of the sender. Look all around the top half of the engine block and bell housing. Wipe it down with a rag and check for oil. The valve covers and oil pressure sending unit are very common leaks.

[Mighty Hd]

I checked every-thing.

This has been on going for abotu 3 months now and the dealer says they can't find it.


Valve covers are clean @ the heads, the oil pan is just slightly damp aroudn the edges and where the transmission meets the crank its soaknig wet @ that area. errr----it WAS wet.


I've never seen an oil leak just fix it self?

Honest to God the 500 mile trip there I swore it leaked a quart...oil level changed just a pinch though.

I cleaned and scrubbed everything of before we left---500 mile trip home and not the first drop.

[hummertech]

check on the left side of the oil pan above the oil filter where the cooler lines bolt to the pan. there has been an issue with either the gasket leaking or a porous oil pan. (take a little pocket mirror and look above the cooler lines at the pan, its tight up there) had a leak there right above where the lines bolt up and swore it was a rear main seal.(oil travles back along the pan and down the bellhousing) the only way to find something like that is to install oil dye into the oil. run it for a day and then take a blacklight to the leak. the leak will glow in the light. there is also issues with the rear main plate assembly leaking due to undertorqued bolts...the dealer should have oil dyed it first thing. thats what i do. its a for sure thing.