Hello everyone.....new to the site and so far so good. I had the dreaded low end studder problem with the p0401, and with the all of the post on this matter I have fixed that issue. E150 is running great!!!!

This Econoline is new to me it's a 2001 with the 4.2L with 149k on the clock. I'm noticing a weird oil leak which appears to be coming from the rear main seal. Now here's the scoop.

If I drive the van for say 5-10 or miles and park it, there might be a drop or sometimes none at all under the van. If I start the van and move it literally 10-30 feet, when I turn it off and let it sit, there will be a nice size puddle under there.

When I changed the upper and lower intake gaskets I was checking everything out closely to make sure all of the vac lines and whatnots were in good shape. The only thing that stuck out was the pcv valve. It rattles like it's ok but it fits like crap in the grommet. It's very loose. I will check into a new grommet.

The leak has been there since I picked it last week and prior to the intake repair. Any ideas as to why the leak is not consistently leaking at the same rate???

Thanks in advance

 

I'd say the first step would be positive identification of the source. If you could fix that, then the worry over erratic nature would be less worrisome.

If you can't ID the source, I'd clean the area very good with Gunk or similar engine degreaser and start with a clean slate.

I think there is a UV engine oil additive you can pick up at the local auto parts place. Add that to the oil and run the engine a few minutes (I'd do this before cleaning the engine).
When the engine is clean, run it a few minutes then start looking with a "Black Light". I'd think you could ID the source pretty quickly.

Good luck and let us know what you find.