Rear Main Seal replacement - dig me out of a hole??

[Jim]

Hey Folks,

My rear main has been leaking and I decided to tackle the project. (1990 258 / 4.2). The difficult part of the project - removing the upper seal half - is the difficult part and I just put myself in a hole by breaking off the punch at the block (extends about 1/16" - not enough to grab).

I've tried punching / pushing on the other end of the seal - the broken punch bit is not pushing out of the block. The upper seal is not moving.

Is this transmission removal time or does anyone have a tip to resolve the issue with the motor and trans in the jeep?

Thanks,
Jim

[JandDGreens]

Is it so small that you can't drill into it? Just wondering if the smallest easy out would help turn it free?

[The StRanger]

If ya feel confident you can loosen the main bearing caps, and use a pry bar to lower the crank.
only about 3 or 4 threads.
That should be enough to slip it out. Just DONT turn the engine over.

[Java]

I'd try a dremel tool with a titanium bit to make a small hole in it, screw in a screw and pull it with pliers. Or just destroy it with the dremel and take out the pieces. If you haven't removed the upper half and it's still servicable you can leave it, clean the surfaces all around it and coat them with anerobic sealer before you put them together. I'd actually do that even if you replace the upper.

[Java]

Just saw it and I like Sam's answer better.

[FINOCJ]

I've been working the sbc seals over the last week....Getting the top half of of the RMS out is a PITA....as sam said, suggest loosening the main bearing cap bolts a bit....I actually test for what the torque is first, then I know what to tighten them back to....Additionally, I found it helpful to have a helper turn the crank by hand to help move it out, and same when putting the new one in - kinda helps feed it in....not sure what Sam would say with the bearing caps loosened a bit and turning the crank by hand, but that is how I would do it....hopefully not too much damage.



In the one in mine, the split section of the seal was not ideally offset/clocked at bit from the cap/block mating surface - if possible try to offset the the seam between the to halves so they are not perfectly matched up to the mating surface between the bearing caps....in other words, not like this pic....but a smidge of RTV on the bearing cap mating surface is probably helpful....

[Jim]

Thanks folks.

Sam - is your comment of NOT rotating the crank with loosened bearing caps related to a main bearing rotating and not having the bearing split match the mating surface between the block & bearing cap? If that's the concern, I could see, when it's time to tighten the caps, removing one bearing cap at a time to ensure the bearing halves match the seam for the block to cap. Make sense?

I'll spend time with it Sunday... News at 11...

[Jim]

I loosened all main bearing bolts about 1.5 turns. This seemed to give a decent amount of drop. Word in advance - once you loosen those bolts expect more oil to come dripping down from the bolt cavities.

I punched a bit at the other end of the seal and noticed the broken punch bit had slightly protruded. Some side to side pushing on the bit and then needle-nose pliers - pop and out. One item off of the list.

The seal seems to be firmly stuck in its channel. When I'm hitting with the punch I'm debating if the punch diameter is too large and I'm hitting the block or if I'm actually hitting the seal. I've tried smaller punches and am now giving good research to the size of the channel the seal rides in.

Some progress.

Thanks!

[Jim]

IT's OUT!!!!


Pix and details shortly

[Jim]

I went with Sam's advice to lower the crankshaft by loosening all of the main bearing bolts 1.5 to 2 turns (13 turns is full removal). I then, gently, pried the crankshaft "out" of the block at cyls 6 and 5. I also pressed the clutch in as my mind thought it could hinder the crankshaft from easily moving outward from the block (to give some space to allow the upper seal to move / broken punch to be removed). I don't know if the C/S moved much.

From there I worked to clean up the other end of the seal / block area. I wanted a clear view of the U-Channel the seal rides in - where can I place the punch so that I know it's not resting / hitting the block. In the end - I wasn't able to get a clear view of that side. I did have a clear view of the U-channel at the broken-punch side. While I did hit a time or two at the difficult to tell end of the seal I wasn't satisfied hitting at that end - am I hitting the seal or the block.

I felt the broken punch end again and the broken section felt that it had come out a bit. I grabbed a pry bar and gently pried fore and aft on the end - it moved a bit. Needle nose pliers and it popped out. A reassuring step in the project.

Then to resume seal removal. I stayed away from the "unclear" end of the seal and figured I'd try punching the broken-punch-end of the seal again. I grabbed the original larger diameter punch as I could see the U-channel and know I wasn't going to be hitting against the block. It took about three or four solid, heavy hits (more force than I would have anticipated) - but it moved. A couple small hits and I was at the end of pushing it with a punch. Needle nose pliers and it readily slipped out of the channel.

I'll now tighten to spec (80 Ft-Lbs in a 40/70/80 Ft-Lbs step-up - via Jeep service manual) the loosened main bearing bolts. I'll then turn the crank 90deg to inspect the sealing surface from damage I might have inflicted - repairing / smoothing as needed. Then a 180 degree turn for the other area.

A significant step in the project.

Thanks folks for the help!

[Trevor?]

If you had to do it over again, what would you think about using a brass punch? I'm thinking one could swing at that a little harder without worrying about marring up the block or the crank... that and they tend to bend well before they break.

Thanks for posting this. Looking forward to seeing it go back together. I may be needing to do this soon.

[Java]

This is what I meant about the anerobic sealer, but said so poorly. It seals up the area that is prone to leaking between the two halves. You can't use RTV, it won't dry and will not work. I did this to my 258 and my 4.0, neither ever leaked again.

https://www.fourwheeler.com/how-to/e...ear-main-seal/

[Jim]

Trevor? previously posted:

[Jim]

Paul previously posted:

[FINOCJ]

There is nothing fun about replacing a RMS - the old rope style seals are even more fun getting them....really, this should be done once during assembly - I don't know that doing it in vehicle will ever work perfectly, but if your loosing lots of oil then it will certainly help and keep it driveable....If you are trying to stop an annoying but meaningless drip on the floor, I wouldn't bank on much improvement....but you got it done and learned something...hell, I just installed my intake for the 3rd time in 8months and my valve covers for the 3rd time as well, re-inspected my quadrajet again (and made a great improvment), and I am still learning and the jeep is hopefully getting better and yet its nowhere near decent...but then again thats why I buy old POS's...My new philosophy with the willys is it doesn't really matter - just BTFO of it when necessary and don't be afraid to rip it apart and eff it up - its just an old jeep!

There are lot of different types of sealers, gasket tack, RTV etc....I have about 7 tubes/jars of different stuff, and am still learning what applications I like using what types.....Here is one simple summary:
https://www.hemmings.com/stories/201...asket-sealants

[Jim]

My big picture is getting this clutch through the season. I wish to do a reman motor this winter. The large (open palm sized) puke of oil at the gas station near Parachute on the way to Noab last summer was an eye opener (a long freeway day). The RMS started dripping - just a quarter sized dot after being parked for the week - about a year ago. The motor job is on my radar and I "hoped" to make things last. The large puke of oil put some worry on my mind that the clutch might get soaked and cause issues this summer. So long as the drip is much less than what it's capable of, I should reduce some concern for clutch reliabilty this summer.

Years ago, I drove an 80 MG-B from LA to northern IL (helping family). The car had a known oil issue when I left the west coast. I quickly realized it was the RMS. After quickly pumping through two or three "quart singles" I quickly realized I would need to buy oil by the case. The trip ODO was used for oil checks as it would process oil faster than a tank of gas. The clutch worked valiantly until about 250 miles from home in Illinois (rolling farm fields - no mountain grades). At highway speeds the "Illinois hills" would see the speedometer dropping with the tach climbing - the clutch was soaked and slippery. I don't want to experience this with the jeep and was happy to try to resolve or reduce the issue with this seal replacement.

I believe I have worn rings which is causing more crankcase pressure. I'm considering removing the PCV valve and going full open tube from valve cover to intake - to help reduce crankcase pressure. The jeep, at this point, is decently happy with two lane speeds / throttle settings - but freeway & heavy throttle - not so much. One problem free summer is my goal before a large replacement to happen.

[FINOCJ]

Jim previously posted:

[Trevor?]

How many miles are on your 4.2, Jim?

[Jim]

187K on the clock. "I believe" the motor has not been opened but I am not certain.

I purchased it in 06/2011 with 153K on it. The guy I purchased it from filled oil and gas and turned the key - little to no mechanical involvement with it. Somewhere before him the jeep had been modified - drivetrain, lift, and perhaps specific to your question (motor work) is that it had been converted from original carb to Mopar MPFI. The head might have been swapped (one person I spoke with who looked at the motor said it has a newer head - I don't know casting ident). I don't think the bottom end had been changed / worked on but I don't know. I'd like to chat with the person who mod'd the jeep (though by now I have most questions answered - figured out what I bought).

08/2011 compression test (I think I read that the 4.2's compression numbers are in the 120 to 150PSI range. 4.0's are 170 or 190PSI IIRC). Hmm - at that time, compression was decent. I should re-check.

Grey hand push to block compression tester used. Only one hand used to hold it to the block (some seepage possible). Air filter removed. Throttle plate opened. 4-5 compression strokes. Partially warm motor. Front to Back: ~145, ~145, ~150, ~145, ~140, ~145

[The StRanger]

I love it when a plan comes together.