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Replacing rear main

Replacing rear main

Germy

Full Time Jeeper
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Location
Cincinnati, Ohio
Vehicle(s)
1985 jeep cj7 360 20 rear and 30 front w/warn lockers 5 speed tranny,

1971 dodge dart built 318
Ok, leaking rear main. I read to loosen the bolts on the crank to drop the crank a little. Slide the two pieces in and re torque main bolts. Is it this easy? Anyone have any first hand on a 360? Also want to do pan properly, do you put rtv in corners let dry then install or install wet?

Thanks!!!!!
 
You want the RTV to be wet so it can swish out when you tighten the bolts.
I'll let an AMC guy answer the rest.
 
You want the RTV to be wet so it can swish out when you tighten the bolts.
I'll let an AMC guy answer the rest.

This.

I'm not an AMC guy by trade, but having done a re-ring and gasket job on a 360 with the block still between the frame rails, I think I'll take a stab at answering.

Yes -- you must remove the rear main cap, and you can get one half of the rear main seal out of the cap. For the half in the block, you must use a small punch to gently puch up (tap the punch with a hammer gently) on one exposed end of the seal to get the other end to start pushing through. Then you can feed the new seal up around the crank.

If you try to drop the crank with only the rear cap removed (which won't happen with a LOT of prying, putting a ton of side load on the crank mains -- BAD thing) you could put some permanent deflection, i.e. a bend in the crank. Just try pushing the old seal out, then pushing the new one in. You'll see what I'm talking about when you get under there.

When you're putting the cap back on, use a dab of RTV at the ends of the rear main seal between the halves to seal them up and prevent any more leakage.
 
Mine was much easier than I thought. Drop pan . Remove the main cap and Loosen but dont remove the next 2 caps. Harbor freight sells a nice long punch set. Tap out the old. Some light oil and install. Buy two in case you booger one up. Reinstall cap and torque bolts. Install oil pan with a one piece silicon gasket. Not much more to it. Prolly a good time for a new oil pump. Perhaps a timing chain.

Sent from my Galaxy S3 with Taptalk 2
 
Thanks for the tips!!!!!!!!
 
After you get the new seal in as stated above and use silicone in the corners of the pan gasket, I have had good luck using high tack on the rest of the pan gasket. It won't squish out the gasket and removel the next time is easyer.
 
I've been using Indian head on cork with great results, valve covers, oil pan except where rubber meets. We are starting here soon, I'll have some pics!


Sent from my iPad using Tapatalk HD
 
Just something my old shop teacher showed me on my first jeep. When doing the rear 2 piece seal, get a piece of plastic (like the kind that is used to package things that seem impossible to tear open). Cut an exaggerated "T" shape out of the flat area of the plastic. You will have to trim the long part of the "T" to fit in the grove of where the seal goes in, and use the top part of the "T" as a handle. A little oil on it and the seal and the new seal will slide in easier without tearing from the edges of the block. I've used this tech. Since high school and its never failed me once :)
 
Just something my old shop teacher showed me on my first jeep. When doing the rear 2 piece seal, get a piece of plastic (like the kind that is used to package things that seem impossible to tear open). Cut an exaggerated "T" shape out of the flat area of the plastic. You will have to trim the long part of the "T" to fit in the grove of where the seal goes in, and use the top part of the "T" as a handle. A little oil on it and the seal and the new seal will slide in easier without tearing from the edges of the block. I've used this tech. Since high school and its never failed me once :)

My seal came with the little plastic "t" did not use it.

Sent from my Galaxy S3 with Taptalk 2
 
I have read everything here and it renewed my confidence but I still have one question everyone at the auto-zone needed to know if I have a single or a double seal. How do I know?? It is harder to change a single we have a AMC 258 i6 / 4.2l I think it is an 1980 or so
 
Last edited:
I would call it a single seal. I was not able to remove the upper seal on mine and was not going to drop the trannys and clutch to do so. I just replaced the lower seal and it stopped leaking.
 
The rear main oil seal consists of a two piece neoprene single lip seal that needs to be installed correctly so it doesn’t leak. I first removed the rear main bearing cap (you can see the lower seal in the cap).

DSCN1871.webp

I removed the lower seal and cleaned the cap of old sealer.

DSCN1872.webp

I loosened all the remaining bearing cap bolts and used a brass drift to tap out the upper seal enough to grab it with pliers from the opposite side.

Note: on the outer edge of the seal there is a wire (this is what I tapped on with the brass drift).

DSCN1873.webp

I cleaned the block seal surface and lightly oiled. I coated the block contact surface of the new upper seal with soap and the lip seal with engine oil. I then pushed the upper seal in the engine block.

DSCN1874.webp

I coated both sides of the new lower seal end tabs with black RTV and the outer curved surface with soap and the lip with oil. After setting the lower seal into the cap recess I put some black RTV on both chamfered edges of the cap. I also laid a bead on the block as well.

DSCN1875.webp

I stepped torque all the cap bolts at 50, 80, and 100 ft/lbs (AMC 360)

DSCN1876.webp

Hope this helps
 
It def does torx! Tackling again tomorrow. Still leaking after mechanic changed it. Hope this does it
 
Im starting to think it is coming from above the rear main. The rear has had two pro installed seals installed. New clutch because of oil splatter. Now its still leaking, ruined another clutch. Im going to check valve covers and back of intake first. It only leaks for a second after running, then it stops. Ive replaced pan gasket multiple times and twice professionally done. I dont want to pull the tranny, think ive fixed the problem, install a new clutch then start the whole cycle over again
 
Not coming from up high. Im thinking seal, pan gasket, freeze plug on the back or the two drain plugs behind flywheel
 

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