I have a buddy that owns his own independent repair shop, who offered to do my rear main for $250 plus parts. That's with the usual caveat that the price is good as long as the repair goes to plan and nothing else is wrong that needs work.

He seems to know his stuff, I stopped by his shop this afternoon and he's got several vehicles he's doing engine swaps and other major work to.

The repair is nothing I can't do myself, but spending 6 or 7 hours laying on my back underneath the truck in winter weather is far from what I consider the ideal weekend. For $250 I figure I'll save myself the headache..

However, when I suggested that the rear main seal comes out from the oil pan (having to pull the rear main bearing cap), he acted like I was smoking crack and basically said "no way, pulling the transmission is easier." I argued the point but gave up because he was insistent that pulling the tranny was the easier way.

I don't really care how it gets done (pulling a tranny would be the absolute LAST resort if I were doing the work), but can the rear main actually be replaced from the back of the engine? From all the research I've done (forum, Google, Chilton's, etc.), the RMS is accessed from inside the oil pan with the rear main cap pulled. But I've never actually been inside a 460, so I can't say for sure if that's the only way.

I don't want this guy to charge me double from having to pull a tranny only to decide that it was a waste of time, and go in through the oil pan like I suggested. I have no idea if he has experience with 460's. If he's the one smoking crack, I'll just do the work myself and avoid the surprise "it's going to be twice as much as I thought" routine.

Any info, etc would be appreciated!

 

I have changed the rear main seal on my 86 F350 with a 460 with a C6. You have to remove the pan. It is a two piece seal. I did it in the frame. It is a lot of work. It took me two days in my own garage on jack stands. I had to seperate the transmission to get the crankshaft to drop enough to get the top half of the seal out and back in. I knoe the 302/351/400 eng. have a regular lip seal that can be changed from the back of the engine.

 

Only the newer 302's and other newer engines with the update one piece rear main can be pulled from the rear. Your older 460 is like the other older engines, the seal is 2 piece and fits inside a groove in the block and in the rear main cap. You have to take the rear main cap off to get it out, and to do that you have to pull the oil pan, which is a really fun job with the engine in the truck.

I think they changed the 302 around 1985 or 86. All the earlier ones where the old 2 piece, and if you go even earlier, you will see them with the original rope seal in the back, that fit in the same groove. I don't know if and when they change the 460 or any of the other engines. All the new designs like the modular engines are probably one piece.

 

Geez, I hope I don't have to separate the tranny *and* drop the pan. This would be a project much better suited for springtime... I wonder if having a manual tranny negates the need to pull the tranny away from the engine?

Also, will I find a rope seal in a 1985, or the rubber two piece dealy that I got from Autozone?

 

You can leave the tranny alone, you do not need to mess with it.

 

Thanks guys for the information you've provided so far. I've decided to just bite the bullet and do the work myself, since I have a little time off for the holidays, and the weather hasn't been too terribly bad lately.

I still have a couple questions on the RMS R&R procedure that I would *greatly* appreciate any help with.

I understand the front of the engine has to be jacked up in order for the oil pan to clear the crankshaft and bearing caps & oil pickup. I suppose putting blocks of wood under the harmonic balancer and jacking there is the correct way to do this? What is a good estimate of how many inches it needs to come up?

I'm pretty sure I will need to remove the fan shroud, as the fan will probably hit it as I jack up the engine. What do I do with the exhaust? It looks as though when I raise the engine, it will hit the rear of the oil pan, preventing it from coming down.

If exhaust removal at the manifolds is necessary, I'm concerned that the bolts will break. Keep in mind this exhaust has been underneath the truck for 29 years. The bolts are so badly corroded that I can't even make out the threads past the nut. Rather than be caught unprepared, I am just going to assume these will break. What are my options here? The truck is my daily driver, and I cannot drive it without an exhaust. Also, because of the tight space, I can't see getting an impact in there. How do you guys normally handle this?

Is there anything I'm missing that needs done for the oil pan to come off? I think once I get in there, I can get the seal out and in no problem, it's getting the oil pan off that concerns me. Just trying to keep surprises to a minimum; I don't like surprises, especially when this is my only vehicle at the moment.

Thanks in advance for any help / suggestions / info, etc.! Oh, and I still don't know if an '85 is going to have a rope seal..? Someone told me I will have to remove some kind of seal retainer if the original seal was a "rope" style.

 

You should be spraying the manifold bolts every chance you get with some pb blaster, wd-40, or the like.

As far as the 2 piece or one piece rear seal, my 85 with 351w had the one piece that you don't have to drop the oil pan for, you just tip tap it in with the tranny removed.

If it is the 2 piece though, it might actually be easier to just remove the engine. I know that sounds like a lot of work, but you would be surprised how long you might spend on getting to, and most importantly, installing the 2 piece seal without damaging it with the engine in the truck.

 

I'm with jpalmer81 on this one

 

I don't have a crane or a hoist for getting this heavy pig out of the truck. It has to come out and go in through the bottom unfortunately.

 

Take your time and do it right

 

How bad is it leaking? If it's not that bad, I think I would try one of the engine stop leak remdies you can buy in the store. It has some stuff in it that attacks and softens the rubber in the seals, and they will stop a minor leak. I have also used brake fluid, poured one of the small cans of it in the engine, and it will slow down minor seal leaks also.

And have you looked this thing over and cleaned the engine off really good. Many times people think it's the rear main because there is a drip of oil back there. But there are many other things that can cause a leak back there that looks like a rear main, like valve covers, the rear intake seal, and if your engine has the oil pressure sensor behind the intake, they can leak also.

 

I'm 99.9% sure it's the rear main. I've replaced every other seal and gasket in the engine besides the oil pan gasket. I just replaced the oil pressure sender unit, so it too, is good.

I can get a pretty good view of the back side of the engine from underneath the truck. While most all of it is covered in a nasty goo after 29 years, the top of the bell housing is notoriously clean. It's clear that the oil isn't making it's way down from up top. Also, most of the oil is dripping from inside of the flywheel inspection plate. That's a pretty good indication the oil is coming from the RMS, am I correct?

I'm adding about 1/2 qt. every 300-400 miles. Oil is cheap, and having to add it doesn't bother me-- But it is really making a mess (now looks like EVERYTHING from the engine back is leaking, including the rear diff) and occasionally stinks in traffic from the oil getting on the exhaust.

 

In the event that the exhaust manifold to downpipe studs do break off, what are my options?

 

Pull the whole manifold off, drill the old ones out and install new studs. I am surprised yours haven't been replaced yet. Most of the 460 exhaust manifolds crack for some reason.

If you are careful and spray them, you might be able to get them off. I could not believe it, but I got mine off the other day on my 89 diesel. I sprayed them, and was very careful with the impact and a long extension, loosening, tightening, back and forth till they finally came off without breaking the stud.

 

Well I decided to spend my Christmas underneath the truck replacing the rear main, since I have a couple days off and the weather is decent. Time is not on my side as I spent the better part of today in bed sick with bronchitis. That leaves me with just the whole day tomorrow to get the truck back on the road.

Right now I have the exhaust nuts at the manifold off. These weren't nearly as hard as I'd thought. But do I need to take the whole exhaust pipe off, or is just having the nuts off sufficient to allow the motor to raise high enough? My Chilton's is not real clear on this.

I've also got the nuts taken off the motor mounts and fan shroud loose. I believe I'm at the point where I lift the front of the engine and get to work on and inside the oil pan. Does this sound right, or am I missing anything?

I appreciate all the help and responses- input from those who've done this I've found to be a lot more helpful than just my Chilton's which can be pretty vague. I thought once I got past the exhaust manifold nuts, it would be smooth sailing. Any other challenges I should be prepared for?