It's been almost three weeks since I bought my 91 F150 XLT Lariat with a 5.0 V8 (that would be in my signature if I knew how to change it). Now that the steering and brakes are sound I have to replace the rear main oil seal. The procedure is entirely different whether it's a one or two piece seal. Any idea which it is? I'll have to rig a floor jack somehow or borrow a gorilla to pull the transmission if it's a one piece (no tranny lift). The days of being young and wrestling one in and out by hand are over, it sucks to get old . That stop leak "snake oil" looks better the older you get! Any tips tricks or advice would be great. I should be doing it this weekend.

 

According to NAPA it should be a one piece seal.. Sorry......

 

Oh wonderful! Time to buy the beer for that gorilla. If it were two piece I could have done it myself. More work but no heavy lifting. Any tips or problems I might encounter would be nice. This will be the first 5.0 seal I have done. I assume it will be straightforward, pull the tranny and flywheel, then replace the seal. It's always the easy sounding jobs that cause the cussing and throwing of wrenches lol.

Thanks White 97 XLT!

 

Looks like you have it figured out, just remember to save the cheap wrenches for throwing...

Only real tip I have is fill the back side of the seal with grease if it has a spring in there..

 

Here's alittle trick I have used. You don't have to pull the tranny you can slide the entire tranny,transfer case and cross-member back in the frame. Disconect everything like you going to pull it but don't disconnect the tranny mount. unbolt the cross-member to the frame then slide everything back and support it.This is also how we do it at the shop.

also a improper functioning pvc and breather can cause excess pressure buildup in the crankcase and push oil past the rearmain seal. If there is excess blow by due to worn rings that can cause rearmain leaks as well. If either of these two possibilities exist then replacing the rearmain will only be a temporary fix. I have seen it happen many times.

 

Interesting...I never made the connection to the pvc valve like that before. I'll be changing mine, as I have a small leak as well.

 

Wahoo! Thanks Forduty, you made my day. I would have never even thought about that. GREAT tip! I'll be adding a new PCV valve to the shopping list. That makes alot of sense. Since I am replacing both valve cover gaskets anyway that should be one of the easiest steps to complete .

 

if you are changing the pcv valve make sure the breather is clean and has a new filter.A new pcv valve won't help if the breather is not in working order.most people overlook the breather.take the breather cap off the motor and clean it with carbclean and compressed air. and give the motor a couple days as the results will not be instantaneous.

 

Thanks for the help Forduty. Forgive my ignorance but where is the breather filter? On my 91 f150 V8 5.0 the PCV hose goes straight into the upper intake manifold. I must be simply having a brain fart but I don't see it lol. Both valve covers have no breather just "oil in" on driver's side and PCV on the other. By the way, is the EGR system affected by higher than normal crankcase pressures? That is the last code I have to clear up on my engine, 33 (EGR valve opening not detected). I had intended on cleaning it with brake cleaner when I did the valve covers and see what happened. I really havn't thought much of this problem yet. I am just prioritizing problems such as brakes, steering and other safety issues first. If I tried to tackle all the problems I would get lost! It's been barely three weeks since I drove it home. I'm still in the basic life saving (truck and mine) measures mode.

 

Most motors that use a pcv have a method of letting fresh air into the motor.You can look at your emissions sticker or open up a repair manual and that should tell you the location of the breather. Most factory setups have a hose of some sort either being rubber or abs plastic that allows fresh air into the motor through a valve cover from the air cleaner setup.This hose is typically on the valve cover opposite of the pcv valve.Some of the systems use a paper element and some use a type of foam to filter the incoming air.

The egr valve that is not seating properly will cause a vacuum leak. Highly unlikely to impact the crankcase ventilation enough to cause a rear-main leak.

 

I'd just like to add a quick suggestion to pop the old seal out pretty easily. I just had to change it on a motor that I was putting in my pickup. What I did was start a 2 1/2 or 3 inch deck screw into the center of the seal, then put a chunk of 2x4 on the crank so it wouldn't get damaged, and then I just put a claw hammer on the screw and against the wood and hit the hammer handle once and it popped right out.