Could a bad / loose input shaft cause rear main seal to leak?

matt4282

matt4282

Member
Joined
Oct 24, 2019
Messages
83
Location
katy texas
I had a shop install a new rear mail seal the day I picked it up it started leaking. I took it back and they replaced it but they said they think the input shaft has gone bad or loose. Which is causing the rear main to keep leaking. They said they had the Jeep idle for an hour to check for leaks and nothing was leaking. Everything looked dry when I looked at it. Drove it 5 minutes to the gas station after picking it up and was leaking again. Has anyone had something like this happen or knows what is happing?
Thanks
 
matt4282 said:
I had a shop install a new rear mail seal the day I picked it up it started leaking. I took it back and they replaced it but they said they think the input shaft has gone bad or loose. Which is causing the rear main to keep leaking. They said they had the Jeep idle for an hour to check for leaks and nothing was leaking. Everything looked dry when I looked at it. Drove it 5 minutes to the gas station after picking it up and was leaking again. Has anyone had something like this happen or knows what is happing?
Thanks
Click to expand...
They are not connected. In fact, if the input was loose, that would (if possible) put less side load on the end of the crankshaft and promote rear main seal life. Of course that's all bullshit but if one were to try and make that case, looser would be less load on the crank. Reality is the crank is well supported by the rest of the bearings and nothing to do with the transmission is capable of affecting that.

Your experience is also why I do not warranty a rear main seal job further than 10 feet. There is nothing I can do better than the factory did to prevent a leak right away or ever and there is a very high percentage of them that leak from the factory work at some point.
 
mrblaine said:
They are not connected. In fact, if the input was loose, that would (if possible) put less side load on the end of the crankshaft and promote rear main seal life. Of course that's all bullshit but if one were to try and make that case, looser would be less load on the crank. Reality is the crank is well supported by the rest of the bearings and nothing to do with the transmission is capable of affecting that.

Your experience is also why I do not warranty a rear main seal job further than 10 feet. There is nothing I can do better than the factory did to prevent a leak right away or ever and there is a very high percentage of them that leak from the factory work at some point.
Click to expand...


That’s good to know about the input shaft. I get that factory seal go bad and leak at some point. But I don’t quite understand why do you think a new seal Wouldn’t prevent a leak.
This is a few hours after being parked.
Any suggestions on what I can do to fix this ?

CAAE9DCD-4B49-4C1C-81B7-D8EC9E51BC1C.jpeg
 
Try what cured my really bad BMW's RMS leak... replacing the engine oil with a high mileage CONVENTIONAL 10W-30 engine oil. High mileage engine oils have high levels of seal conditioners that can restore the seal back to its original shape and size.

The oil that cured my bad RMS leak was Mobil Super 10W-30 which is a conventional engine. This is especially likely to help if your engine has been running on synthetic engine oil which is more prone to encourage RMS leaks.
 
Jerry Bransford said:
Try what cured my really bad BMW's RMS leak... replacing the engine oil with a high mileage CONVENTIONAL 10W-30 engine oil. High mileage engine oils have high levels of seal conditioners that can restore the seal back to its original shape and size.

The oil that cured my bad RMS leak was Mobil Super 10W-30 which is a conventional engine. This is especially likely to help if your engine has been running on synthetic engine oil which is more prone to encourage RMS leaks.
Click to expand...


Thanks I’ll give it a try. But do you think it will work for a brand new seal?
 
Jerry Bransford said:
Try what cured my really bad BMW's RMS leak... replacing the engine oil with a high mileage CONVENTIONAL 10W-30 engine oil. High mileage engine oils have high levels of seal conditioners that can restore the seal back to its original shape and size.

The oil that cured my bad RMS leak was Mobil Super 10W-30 which is a conventional engine. This is especially likely to help if your engine has been running on synthetic engine oil which is more prone to encourage RMS leaks.
Click to expand...
Mine has a very small rms leak and I am going to give this a try, if not it is so small I will live with it until I have time to do it myself. Love this site it is very helpful.
 
Jerry Bransford said:
It is worth a try. My BMW was leak-free the last couple years I owned it. Especially if it has been running on a synthetic which is more prone to encourage RMS leaks.
Click to expand...

Online I can only find Mobil Super High Mileage Synthetic Blend Motor Oil 10W-30. Is that what you used?
 
matt4282 said:
That’s good to know about the input shaft. I get that factory seal go bad and leak at some point. But I don’t quite understand why do you think a new seal Wouldn’t prevent a leak.
This is a few hours after being parked.
Any suggestions on what I can do to fix this ?

View attachment 183908
Click to expand...
The reason that I believe a new seal can leak is the same reason the old seal leaked. It is a crap design and some of them leak. There is nothing I can do to ensure that they won't leak except to put it back new with the exact parts it came from the factory with that also leaked.
 
Also possible the crank is scored and ruining the seal, a buddy of mine had the crank replaced under warranty due to the scoring and non stop leaking
 
They might have installed the seals facing the wrong way or dint use the anaerobic sealant. Or maybe it just took a crap like Blaine said.
 
matt4282 said:
I have high hopes. Changed my oil today and after the first test drive went from that big mess in the picture above now just a few drips. Hopefully after a few days it will completely stop dripping.
Click to expand...
Good luck, I was very pleasantly surprised when it completely stopped my RMS leak.
 
  • Like
Reactions: matt4282
Top Bottom
Back