Rear main seal crankshaft issue/ need advice on next step

[TPS]

Ok so I own a 1974 CJ5 that is for the most part in great condition. It was restored in 2001 by a PO and after restoration and some use it did some aging in a barn. Over the past couple years I have replaced a lot of the wearable items and gave it some TLC to get it back in reliable shape. Engine runs great, new suspension/starter/alternator/plugs/filters/valve cover gasket etc and to top it off it's rust free with a solid paint job. I really love this jeep and I have tried to fix anything and everything if it needed attention and this is where my problem lies. When I bought the jeep it had a rear main seal leak. I have now replaced the main seal 5 times and after learning a little more each time I have discovered my issue. The crankshaft should have knurling or helix engraved on it where it rides up against the seal that slings the oil back away from the seal. The problem is mine doesn't, it's as smooth as well you know. After finally figuring this out through all my failed attempts and research, my question is where do I go from here? I've ran out of rescources locally and figured I would turn to the knowledgeable folks here on this forum. If anyone has tackled this issue before or has suggestions I would appreciate anything you are willing to offer! Thanks

 

[Lumpy Grits]

:ww:

Are you SURE, it's the rear main and not tranny?
What weight engine oil do you use?
How much does it drip-
AMC engine are well known for drips-Mine Has done such since I bought it in 1985.
LG

 

[TPS]

Thanks for the welcome and the reply LG. I'm fairly positive it's the rear main, it is the only place my jeep leaks at all everything else is fairly dry. It leaks out the bell housing and it's been bad enough that I've had to replace clutch and pressure plate. I've tried every seal you could think of, double lip, single lip. Last time I put a little rtv down first then put the seal in to try and raise the seal a little and this kept it dry for a while but it's back at it again now. My guess is that when it was restored in 2001 it was rebuilt bc the bearing caps are stamped. If that's the case I assume someone ground the crankshaft and took the knurling off. I don't have a pic of mine but it is smooth and from what I understand The crank shaft is suppose to have a light knurling or helix. I've read a few places where people have tried rope seals but that seems like you would never get a seal to me??? I guess I'm trying to figure out if there is anything else that can be done or I either live with and replace the clutch every so often or rebuild and fix crank. I can't do the latter myself so I'm hoping someone's had this problem before, and remedied it!

 

[Lumpy Grits]

Tranny input shaft seal leak, will come out of the b'housing too.
How much of a leak is this?
You need to ck the oil level in the tranny and t'case.
LG

 

[TPS]

Ok so checked the tran and transfer this weekend, levels are good. Also to answer your question on the previous reply I'm running 10w30. The drop has progressively gotten worse on each seal replacement. The last time I replaced it it stayed dry for a while, maybe a drop would gather on the bottom of the bell house. I don't drive it that much, mostly weekends around town. It's been about 3 months since I last replaced the seal and it's starting to leak pretty bad, ran it for about 10 minutes in the driveway today and had about a softball size spot. Clutch is starting to chatter again and I just replaced it with pressure plate at the beginning of summer.

 

[Lumpy Grits]

How cold does it get in the winter where you live?
Think'n a heavier oil like 15w-40 or what I run that is 20w-50 Castrol high mileage.
LG

 

[jafo]

Ok so I own a 1974 CJ5 that is for the most part in great condition. It was restored in 2001 by a PO and after restoration and some use it did some aging in a barn. Over the past couple years I have replaced a lot of the wearable items and gave it some TLC to get it back in reliable shape. Engine runs great, new suspension/starter/alternator/plugs/filters/valve cover gasket etc and to top it off it's rust free with a solid paint job. I really love this jeep and I have tried to fix anything and everything if it needed attention and this is where my problem lies. When I bought the jeep it had a rear main seal leak. I have now replaced the main seal 5 times and after learning a little more each time I have discovered my issue. The crankshaft should have knurling or helix engraved on it where it rides up against the seal that slings the oil back away from the seal. The problem is mine doesn't, it's as smooth as well you know. After finally figuring this out through all my failed attempts and research, my question is where do I go from here? I've ran out of rescources locally and figured I would turn to the knowledgeable folks here on this forum. If anyone has tackled this issue before or has suggestions I would appreciate anything you are willing to offer! Thanks

Actually, I thought the seal was designed to force the oil back into the pan area.

What I would check first is make sure you are puting the correct amount of oil into the engine. I would go by the factory service manual. I had been over filling going by the dipstick. When I changed my rear seal, dropped the pan and seen the tube was bent forcing an inaccurate register on the stick resulting me in overfilling and leaking out the seals. This happens when adding oil only, not just after oil changes.

Second, I may question the seals themselves. What brand of seal is it? Are they the right seals? Another thing is damage to the new seal during installation. What procedure are you using to install the new seal? With the main cap off, what does the crank journal look like? Just a small amount of dirt or left over gasket material can ruin a seal in a flash. I assume you do lube the seal contact surface also.

Just some things to look at. When I did my rear main, I started by cleaning everything around it before pulling it apart. Dirt can fall into and onto the seal and you'll never seal it. Then I keep it clean through out the job. I lube the seal good, I use a brass drift only on getting the old seal out. Manual recommends soap on the backside to aid in installation to the block. Then I use regular oil on the journal side of the seal and slide it in. Should be easy to slide in. If not, somethings wrong. Tiny amount of sealer on the end I think it was and then button it up and go.

Hope this gives you some ideas.