86 460 rear main leak

[AJBH]

I've got an 86 F250 with a 460, and the rear main has had a slight drip for a long time. It sat for a few months, and the when I restarted it the leak was much worse. It also has a bad PCV valve. I have heard this can aggravate a weak rear main. Any thoughts?

 

[Fellro]

If it is stuck shut, it can. Sitting is hard on seals in general.

 

[Evan's f250]

change the pcv valve and put in a lil thicker weight of oil, it wnt leak as much.

 

[k9baddawg]

I have a 85 f350 duelly crewcab also with the 460 also have the rear main seal leak found out that marvels mystery oil may contain tranny fluid.. that being said i added just a bit of tranny fluid too my oil occaisionally ... tranny fluid cleans but in my opinion swells the seal and it doesnt leak as much.. but get other opinions b4 you try this it seems too work for mine

 

[SuperCab]

There are ways of swelling seals... most of which are effective but dangerous.

We had a chevy med. duty truck... 50 series or something... with hydroboost brakes. when dad and I went to pick it up after buying it the prev owner told us some of the quirks it had... blah blah blah... and added that he'd filled the brake fluid up because the brakes weren't working, but they were fine now."You know the brakes and power steering are connected on this?" Yeah... Didn't think about it. until the paint started peeling off the power steering fluid reservoir and we realised what he'd done... Filled the power steering up with brake fluid.

It stopped it from leaking though...

 

[Fellro]

I have done the trans fluid in the oil before. It does a couple things as you noticed, it is high detergent so it cleans the varnish off inside, as well as has seal swell agents.