I have a 1985 f250 460 that I'm pretty sure is leaking from the rear main seal. Just wondering my options or any advice on fixing it.

 

Before pulling the trans and flywheel to replace that seal, it would be a good idea to make sure it is not coming from the valley seals higher up on the intake manifold and also make sure the PCV system is functioning correctly and not allowing excess crankcase pressure.


Are you by any chance using full synthetic motor il?

 

After taking a closer look I see that it's actually leaking from the back side of my vale cover. No I am not using fully synthetic oil. I am using valvoline conventional 10w30 with motor craft oil filter. What do you suggest I use? Thanks for answering.

 

There are mixed reviews regarding using full synthetic in older hi- mileage engines. Some have complained it has opened up leaks that never leaked before and others say it was going to leak there soon anyway. I do run full synthetic oil in everything and did have to replace valve cover gaskets/seals in one motor with only 140,000 mi. Older seal material may/may not be comfortable with full synthetic. It has worked well for me. If everything is working well up to this time with the oil you are presently using , may not be a bad idea to continue using same.