My truck has been leaking oil especialy on a long drive, the oil ends up all over the tailgate and window, I have had the Valve cover gaskets replaced and it still leaks, I think it is the rear main seals, my question is if it is not the rear seals where else can it be leaking from and what should I look for to determine where it's coming from. The engine is an 85 302 fuel injected with auto trans.

Bill

 

If you're getting that much oil on everything, it would just about have to be the rear seal. What you need to do is give the engine a good washing down to find all of the leaks

 

If not the rear main seal or valve cover gaskets, it could also be the oil pressure sending unit, the oil pan gasket, or the front timing cover seal. If it's blowing it out enough to have it end up all over your tailgate, I would almost suspect the rear main.

Do check your PCV valve and breather filter. If this is not operating properly, your engine will force oil out of the seals. Just a couple of thoughts. Hope this helps!

 

I checked the PVC valve and breather and they are working, also checked all other possible places and it seems to be the rear main.

Does the trans. have to be pulled to replace the seals, I think they are a two piece seal according to my manual, if it is a major job what would it cost to repair?

Thanks, Bill

 

Apparently the rear seal on my 96 is leaking, but I haven't had a chance to fix it yet.
Yes you have to pull the tranny to replace it. I think it usually cost between $200 and $300 bucks to have it done.

 

I replaced the rear main on my '83 351 when I replaced the oil pump. Didn't have to pull the tranny, but I did have to pull the fan and lift the engine about 4 inches. No real big deal to do it yourself. If you do decide to do it yourself, go ahead and pull the whole pan and clean it. You'll have to replace the gasket around the whole pan anyway. It only cost me around $75 to do it myself, including the oil pump and new oil/filter. The gasket was only like $20. Just make sure to line up the rear main exactly right or you'll have to do it again. Oh yeah-make sure to get a buddy or two to help you.

 

A word of warning on raising the engine in your '85, though. With the EFI, you won't have as much clearance with consideration to the upper intake. You can unbolt your exhaust and fan (or shroud), unbolt the motor mounts, and jack the engine up by the balancer and gain enough clearance to drop the oil pan 2 - 3 inches, enough to replace the gasket (actually, I have managed to do this AND change the oil pump, but it was a VERY tight squeeze). However, at this point, the upper intake will be against the firewall, and you won't be able to fully remove the oil pan because of interference from the crossmember.

 

If I can get a shop to do the job for around $300 it sounds like the best way to go, thanks for the help everybody.

WildBill