Rear Main Seal Help - F134

Two little chunks of the very end of the rear main seal pulled off with the old gasket material as I was removing the oil pan gasket.

Does this mean I need to replace the whole rear main seal now?

Each end of the seal was stuck to the old gasket. Now there are 2 little 1/4" divots where the ends of the old seal used to be. The manual says they should stick out about 1/4" in order to compress and seal the crankcase against the oil pan.

Can I just shot some rtv black in there when installing the pan gasket? Or ball up the material again and cram it back in the holes?

Please help. The rear main wasnt leaking before. it would be a shame to have to replace it now.

 

Those are not the actual "Rear Main Seal" they are the rubber dowels which come with a main seal set. They just slide in, and should not be coated with sealant, and as you said they should stick out about 1/4".

I would pull them out and replace them with new dowels. The reason they are made to be compressed is so they will seal the joints between main cap and block.

May be difficult to pull them out, but I have done it by threading a deck screw into the center after drilling into it with a bit smaller than the threads of the screw, and using a claw hammer on the head of the screw to lever the dowel out. I am sure others have done it differently.

 

Interesting! These are definitely made of rope/cotton looking material.
Would it be ok to pull them out and replace with rubber even if the other main part of the seal is rope?

 

I'm thinking that is part of the rope seal and should be replaced. i would if it was mine it is a fairly easy thing to do with the pan already off.is the engine on a stand or still in the vehicle? If still in vehicle it's a bit of a chore but doable.

 

Nah Peep, the circled areas on the picture are the dowel seals, not the main seal. I wondered what the fiber looking stuff was on the picture of the gasket. I have never encountered the rope/cotton dowel seals, must be pretty old and that might make it more difficult to pull them.

And yes you can use the rubber dowels, which are all I have seen in recent years.

 

Cleaned off the oil pan gasket on the 64 CJ5 and the rubber dowels just fell out. Pushed them back in and will replace them with the rear main seal. Must have 4 or 5 of the neoprene seals lying around. Just have to see which ones work best when I put the body back on the frame and get it running again.

Dave

 

The engine is still in the vehicle. I was buttoning up a huuuuge list of winter time to-do's and really looking forward to finishing haha. thats how it goes I guess.
Are you saying the entire rope seal needs to be replaced? Or just the dowels? Is it all one piece when its rope?

Any links showing how to get it done in my garage with the engine in the vehicle will be hugely helpful.

 

No, the dowel plugs are separate from the main bearing seal. The main bearing seal goes around the crankshaft journal and there is no way for it to be also part of what goes into the bores between cap and block for the dowel plug seals.

This should be clear enough if you study the service manual, or even just look at a picture of a main bearing seal kit.

If you rear main seal isn't leaking there is no reason to pull the cap to change it, the rope seals, which is likely what you have, last a long time.

I said I would pull the dowel plugs and replace them, but if you want to try a glob of RTV that might work, and all you risk is the cost of a new gasket and having to do the job over again if it doesn't work.

 

You guys just sparked My brain to actually remember something! I just realized that DEEEP in a parts bin in my garage, in a box of random take-offs from the PO, there was a bag of seals. I can't tell if they're all used or not. The ropes have a waxy outer coating but don't seem like they've been soaked in oil or compressed in a way that screams "used". and a few of the rubber dowels don't seem cracked. Some are obviously cut down to some smaller size but I have 3 that are all 2 3/4" long (assuming that's the length of the dowels when new).

Any reason to order new or just try these? I'm not sure if the rubber goes bad over time etc.

 

The two on the left are main bearing seals. The four on the right are rubber dowel plugs than look like they are older than me, the two on far right are used and garbage.

The two near right look full length, but old, flex one see if it cracks or breaks. Were it my engine I would buy new ones.

 

Copy that. They didn't crack when I bent them but i'll order new anyway. When I replace them, I just pull the old dowels and jam the new ones in there? Or do they need to be dressed in some way?

 

Do you have a FSM?

 

Yes but this is all i've been able to find on the topic so far. and It doesn't seem to directly answer questions related to installing just the dowels.


This is the first vehicle I've owned that I've done any of this kind of work to. So every time I get into something new, it's a steep learning curve. The manual is good to have but I've never had any training, coaching, mentoring etc. So at first glance, paragraphs like this are hard to digest unless someone spells it out for me or I can watch a "how-to" video haha.

I appreciate your patience guys.

I've now had the jeep for a full year as of xmas eve. I've got about 500 hrs of work into it so far and and slowly working my way through the vehicle bit by bit.

 

My 1965 FSM (Section D1-72) says to soak the neoprene dowel seal in kerosene for 1-1/2 minutes before installing. Then the protruding ends are to be "squirted" with kerosene and peened with a hammer "to be sure of a seal" at the top end.

Moses Ludell, in his Jeep Rebuilder's Manual, favors black RTV "as a lubricant" on the dowels. Might make sense but personally I hate the stuff generally.

 

Thinking about this more. There was a slight weep from the back of the pan before. I'm tempted to just dab some rtv on the tips of the rope dowels here based on what you've described. The only issue would be the fact they they are slightly oily there now and there would be no way for me to completely clean the area before applying.

This is all my OCD speaking haha.

Moses Ludell. His name has been coming up alot for me lately! I'm currently also rebuilding my ross steering box and it seems as if he is the reigning source of info for that.

Thx for this. Does kerosene soften the rubber? Very interesting.

 

In that case I personally would go with Permatex #2, or their Aviation gasket sealer. (Did I mention that I hate RTV?)

 

Ok so I received my "sneaky pete" today and attempted to remove the old "rope" dowels..... Man....... I think whomever installed them was a combat medic because what I had assumed were pieces of rope were actually about 10 feet of gauze that had been tamped down into the holes and hardened. The first one went ok but i laughed when it was coming out because it was like unpacking a clown car.

The second "dowel" was so compressed and hardened that the sneaky pete couldn't grab it. After about an hour of just dust coming out and not rope (probable asbestos dust), I decided I'd have to bite the bullet and remove the bearing cap. Which meant I had to fully commit to the rear main seal being replaced entirely.

Glad I did.

I had been worried there was also an ancient crusted rope seal lurking but it infact turned out to be an ancient crusty neoprene one.

Atleast now I can see what I'm dealing with.

Should the upper part of the seal just "tap" out? While cranking the camshaft? Seems like I won't be able to use the sneaky pete to get the old one out since its not rope.

I'll be working on it more tomorrow. Any crucial tips are welcomed.

This is the seal I bought to replace:
https://www.ebay.com/itm/112320472680

 

"While cranking the camshaft?" Don't know what you mean with that.

The "Sneaky Pete" will work on that seal, no reason to crank the camshaft, nor the crankshaft.

 

Haha "Turning the crankshaft" is what I meant. Good to hear the sneaky pete will be able to grab it. Just not sure yet how to get it started since the old seal sits flush. nothing for it to clip onto to pull the old one out. I was thinking I cold push it out with something but didnt want to jam on it and mess something up if there is a better way.