I have a '89 F150 302/auto 98k miles on it and it doesn't get driven but a few times a years and I have a major oil leak coming from the rear main seal or pan gasket ? Is this a common problem ? And how hard is it to replace either of these. I am trying to sell this truck but the oil leak is scares people off. It runs great just leaves a puddle of oil everytime you go anywhere.

 

Hey Ed, my dad has the same truck and his rear main seal is leaking also. Its been doing it for a couple years now. When it first started I did a google search on how to replace it and from what I remember it would have been better to take it to a shop that has a lift and let someone else to do it cuz the tranny had to be dropped. I was going to do it for him but Im tired of always crawling under the truck. Replacing the seal didnt seem to bad to do just didnt have a lift. Let me know what route you go.

 

Hello Rob, I am hoping to hear from someone who has done this one. Honestly I just want to sell it. But if I don't get what I am looking for out of it I am going to have to fix it.

 

I'm doing that to my 1987 Mustang right now in my garage. I can only spend weekends on it, so it's sitting on jack stands at this moment. After 20+ years, the cork gaskets on the oil pan shrivels and hardens, and actually left gaps between the pan and block. The rear main seal may or may not have been leaking, but since I was doing this anyway, I went and replaced it.

I dropped the drive train (drive shaft and transmission) as well as the front cross member to drop the oil pan:

https://picasaweb.google.com/1155523...37344823295906

Yes, it IS a pain, but it can cost a few hundred dollars for a mechanic to do it for you.

 

Just as a rule of thumb, when oil is running down outside of engine spacer plate, it is a pan gasket. Down inside(tranny side) its rear oil seal.

 

Not to throw a wrench in the fire here... but I have seen a rear intake seal look and act just like a rear main seal... first thing you need to do is verify where the leak is coming from.

 

A leaking rear intake seal will dribble oil down the back of the engine above the bell housing. Valve cover gaskets leaking in the back will also do that. So the top of the bell housing will be all grimy. Mine had that as well, but I've recently replaced my valve cover gaskets, so I'll be checking the intake gaskets too.

I almost wish that after getting a new car, I could go through the whole drive train to replace every stock gasket and seal with better aftermarket parts as soon as the basic warranty has expired. The standard cork gaskets will be the first to die after a few years, and then it's just a matter of time for everything else. A good aftermarket replacement, like FelPro's perma-Dry line, lasts much longer, possibly for the remaining life of the drive train.

 

Well I was hoping it would be more clear cut on the problem but it isn't. I pressure washed the motor and under side but is still a oilly mess. I try to dig around alittle better. You guys have given me some things to look for. I am scared of what I'll find. I haven't checked the valve covers or intake yet. I guess I should have started at the top DaDAaa

 

The 5.0 that was in my truck leaked like a sieve, I was sure that the rear main seal was gone but after a very good de-greasing I found that the VC gaskets and the oil pan gasket were bad. After replacing them, I thought I had it under control until until a road trip showed I still had oil coming from somewhere.

Upon cleaning the engine again I found the source of the main leak- the oil pan had a rust hole in it!

 

The stock valve cover gaskets that came with my 87 Mustang were cork with metal inserts at the bolt holes to prevent them from being crushed. After a few years, the cork shrunk enough to actually leave the gap between the valve covers and the head. So oil was liberally leaking out, making big messes. I now have FelPro perma-dry metal-reinforced rubber gaskets that hopefully will last longer.

I just buttoned up my car after replacing the oil pan gaskets (also Fel-Pro perma-dry) and rear main seal. Took it for a short drive, and will check tomorrow for leaks. More on my other thread.

 

Sounds like you have a handle on your leaks and hopefully that is all of them. Can you post a link to your other tread.

 

Here it is:

https://www.ford-trucks.com/forums/1...l#post10901699

 

Well I found my oil leak it was the oil pan gasket. The gasket was blown out. And it was a really easy fix. I SOLD the truck this afternoon. And I was honest with the guy about the oil leak and he seemed cool about it. It was a good old truck I am going to miss it. Now I can pull the trans in my F350 and do some front pump mods and replace the front seal in it.
"If it wasn't that it would be something else!"
Thanks guys for all your help