Rear Main Seal

Rear Main Seal

polish85

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Location
Charlotte, NC
Vehicle(s)
1977 CJ5 I-6
1977 CJ5
Ive got oil leaking everywhere and anywhere it can...when i got the car the guy told me it had a small leak and by the time i drove it home from his place (100 +miles) almost all the oil leaked out on the car that was following me...im working on replacing all my gaskets with new ones this weekend and im just concerned with the rear main seal. ive heard they were hard to do. I have the haynes manual and it doesnt describe what to do very well. Can someone please guide me along this process?
 
No matter what engine, it is not a big deal.

Pull the oil pan, remove the rear main cap, spin the seal out, put in the new one, replace the cap, replace the oil pan (with new gasket) and drive away... :)
 
It is not uncommon for the rear main seal to leak on the 258.
Here's a good link that covers how to replace it:
Jeepin.com - Replacing your rear main seal.

Thanks for that link. This past weekend i decided to replace the rear main seal. I didn't realize i had to do a lot more work just to get the oil pan off. I ended up using my jack and a piece of wood to lift the engine up about 2.5 inches and removed the passenger motor mount just to get the oil pan off. I got the oil pan off and got the rear main seal out. (While my friend was hammering out the seal with a small screw driver he managed to crack the little piece of metal between the seal and the round black thing in the picture with the yellow arrows). Did that cause really really big damage or will i be ok??? So since the little piece dint crack all the way through we decided to leave it as is and put everything back together. I used RTV as the sealant and let them sit over night. Today when i finally put the oil in it (i used 5 w 20, i feel like i need thicker oil as well???) and drove it to my friends. By the time i got there, there was oil everywhere!!! So we are going to take it apart again and put a rubber gasket on the oil pan to see if thats the problem (unless someone has any other ideas) I would like to know if i messed something up bad by cracking the little piece and any other ideas on what might be causing the leak. i also thought about maybe getting a new oil pan because that one is possibly bent?
Thank you for your time.
Mike

PS..I think i have the amc 232 i-6 engine but im not sure. From the research ive done on the number on the side of the engine leads me to that. The number is 103E01 with the E being 1/4 inch higher then the numbers. Please let me know if i am correct about that. Thanks
 
The block number tells us that your block was made in 1977, on the 18th day of March, it is not a 258 but rather a 232 with a one barrel carb.:cool:

on the right side of my engine it says 103E01
 
If he broke a chunk out of this it obvious its going to leak rearmain08.jpg as for the pan it can be straightened out by sitting the lip along a straight narrow edge of a vise jaw or anvil and hitting it lightly with a rubber mallet

if he cracked the inner section yes its probably going to cause major problems with seating the seal properly rearmain09.jpg and possible damage to the crank over time
 
Last edited:
Where is the other half of the seal?
 
Where is the other half of the seal?
we got the seal on correctly but between the seal and the cutout for the black circular thing thats on the crankshaft the little piece of metal thats about 2 cm big is cracked...let me know if you know what piece im talking about. what should i do at this point. any way of fixing it or am i looking to have to get a new block?
 
The yellow arrows in the pic are pointing to the other half of the seal. The ring in front is for crank thrust, is that what broke?
 
The yellow arrows in the pic are pointing to the other half of the seal. The ring in front is for crank thrust, is that what broke?
not the ring but right before the ring there is a vary small piece of metal separating the seal from the ring..and its cracked but its still on there
 
Two quick things to comment on. First, 10w30 is probably as thin as you need to go with the oil. Second, I thought I had a rear main seal leak, went through the process you described, without the dink, and still had a large oil leak. It turns out to be the valve cover that's leaking. It drips everywhere and the drips come from the bottom of the bell housing, hence the reason I thought it was the rear main seal. If you have a manual transmission and the clutch is not slipping, chances are the rear main seal is not leaking. Check around your valve cover.

Tommy
 
rearmain09-Copy.jpg a machine shop may be able to weld it and resurface if its not cast
 
only thing the block would probably need to be broken down
 
Looks like you only have two options, button it up and run it or pull it. Did you say it was a 232?
 
Two quick things to comment on. First, 10w30 is probably as thin as you need to go with the oil. Second, I thought I had a rear main seal leak, went through the process you described, without the dink, and still had a large oil leak. It turns out to be the valve cover that's leaking. It drips everywhere and the drips come from the bottom of the bell housing, hence the reason I thought it was the rear main seal. If you have a manual transmission and the clutch is not slipping, chances are the rear main seal is not leaking. Check around your valve cover.

Tommy
ya i figured it was too thin. And im having the exact problem you mentioned. but i can see it pouring out from where it touches the bellhousing. The valve cover is leaking but not nearly fast enough for it to get to the bottom as soon as i crank it up. i will reseal the valve cover today and see if that fixes the problem and get back to you. as for the oil what should i run because when i went to the new oil my rods started clanking.
 

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