Has anyone ever replaced a rear seal in the engine.
I rebuilt a 312 and used the rope seal .
I want to replace the seal with a new type .
how hard is it?
I would like to do it in the truck without pulling the engine.
Any advice on this problem would be very heplful!!
I learned my lesson, this time newer is better .

 

There are several good forums in the y-block area that discuss replacing the rear main seal.

I recently replace the rear main seal on my 59 F100 (a 292) by pulling the pan and working from below. It went MUCH easier than I expected, that is, my expectation was after removing the rope seal was that I would wind up pulling the engine, taking out the crankshaft etc. Read up on the threads - George (the Earl's World gallery) also replaced his.

From what I've heard, sometimes the rope seals are successful - sometimes not. One common problem is that the oil pan gasket goes over the two bolt holes that bolts the rear main seal housing to the block - and there is very little gasket area right where the bolt holes are. This allows oil to flow across those points - which looks just like a rear main seal leak from below. A tip I learned in one of the forums from someone with more experience than me is to fill the bolt holes with gasket sealer to prevent them from being a conduit for oil. Good Luck - 312 main seals are not the same as 292 - only John Mummert offers them, I am told.

 

Neoprene seals for the 312 have been out for about 2 years now. However if there is any wear/groove marks on the crank they will not seal; it has to be perfect. And it requires dropping the crank.

At least the rope seals can be done in a few hours and if you're lucky will work the first time.
Ive got plenty of horror stories I can tell from my younger days!

 

My impression is that you think the rope seal is leaking - it might make sense to pull the oil pan and see if you can tell by looking on the block side of the gasket whether oil has been migrating over the gasket and out.

Also, oil could be migrating over the joints where the rear main seal housing mates to the block - another area to make sure gets some coverage with sealant. Several threads discuss the pros and cons of various RTV-type sealants. You might be lucky and not have a rear main seal leak at all.....

However, I replaced the rope seal with a neoprene seal without pulling the crank - or loosening it. And believe me, I didn't really think it was possible - a task similar to pushing wet spagetti up a ladder. I would think the 312 seal would be a similar process, but you should really defer to those who have done one. A lot of 292 cranks have a knurled surface where the rear main seal goes - the surface on my crank was knurled - but very lightly. There is some conjecture in this forum whether the knurled surface will cause the neoprene seal to fail quickly in this forum - some have suggested that the crank surface would have to be polished to remove the knurling before using a neoprene seal. Well, mine works just fine (so far). If the crank was out of the engine - I would have it polished, but sounds like you're right where I was.

PS - I think rear main seals on y-blocks are meant to leak by design - an under-vehicle lubrication system.

 

Thanks for the info!!

I will try to drop the oil pan and hope that I get lucky.
I will let you know what I find.
Thanks

 

Howdy,

You didn't say just how bad it is leaking. Back in the 70's I replaced the rope seal on my 57 Ford 292 and actually had to do it twice. I initially tried it by trying to shove the seal around the crank with a screw driver. I then tried wire and finally aquired a "Chinese Finger Torture" device that worked pretty good!

I went through 2 seals before I got it right.

I have recently started working on a 55 F-600 with a 239 installed and it needs a rear seal. Only the rope seal is available I suppose.... 5 years ago or so I had to get my Dad's old tool box from CA and just a couple of nights ago I was rummaging through it and found my old "Chinese Finger Torture" device!! I couldn't believe it after all these years it's still in there and it's usable. I guess I can do the "Rope" seal now!!

I am going to check the pan gasket though. It would be really nice if that was the only problem!

I'm not looking forward to another round of "finger torture"


Regards,

Rick

 

Rick,

If that's a 55 239 then you should be able to find a neoprene seal for it. I believe that the diameter of the later 239 journals is the same as the 292.

Paul

 

RICK,i replaced the rope seal in my 54 f100 239 with a neoprene seal from john mummert..im sure some of the senior guys has his web address if you want it..I also replaced the old seal retainer..i bought a good used one from the same place..this seal retainer was made a little differant from the old one..no more

 

Howdy, THat would be great! I know there are 2 different 239's......the EBV and the EBU.


Mine is an EBV and it appears that the EBU has similar heads, cam, crank, etc. Heads are interchangable etc...

Mine (EBV) evidently has different heads, crank, cam etc.

I hope the rear seal is the same. That would be nice. I don't have plans to keep this eng and trans though. Ultimately I want to replace the eng and trans with a Cummins/OD auto.

Since I have taken a HUGE pay cut....I'll be putting that on indefinite hold........Looks Like I'll be doing the 239 for quite some time!!!! So I want to persue the seal rope or otherwise!


RM

 

I did call Mummert and did not get an answer and he didn't call back.

His website does not mention anything about seals.


I did discover that the pan gasket was all ripped up in the back and in one place it wasn't contacting the pan at all! I'm sure that's where most of the oil is coming from.

I did remove the seal carrier and I removed the lower seal. I have not removed the upper seal that goes over the crank yet I I'm not sure I will.

I'll just replace the lower and the carrier seals and the pan gasket. I'll hope that the upper seal will not leak as bad as the whole thing was leaking..

I cannot see how I should remove the upper anyway. Do you just pound it out of there with something that will push up into where the upper seal goes?

 

I was able to push one side of the upper seal (with a screwdriver, making note that a bad misstep would really scratch the crank surface) until I had about 1/2 inch of the seal protruding from the other side. Then I used a needle-nosed pliers to pull it out. Thats the easy part.

After cleaning as much of the crank surface as I could I soaked the neoprene seal in oil and was able to push it into place in the upper part of the block without any tools - this took awhile - maybe three or four minutes, but got it in what looked like a perfect position. It wasn't all that hard, although . . . . I think I was more lucky than smart - the whole time I had visions of having to pull the engine out and take out the crank just to get the seal back in.

Be careful with scratchy-tools around the crank surface! and good luck, whatever you decide to do.

 

Ok,

Well the rope seal was not very expensive.....about $8.

I went ahead and replaced only the lower seal and cap seals... I'll see how that goes. If it's gonna leak I'll bet it's only an occasional drip. I had oil pouring out of the rear of the pan because the pan gasket was not contacting the rear of the pan and lower seal carrier at all!


My main task now is to find another front crank pulley and fan pulley.

Do you know anyone with an old 239 that they're parting out?


tnx/RM