Filthy Transmission

J

Juano007

New Member
Joined
Aug 18, 2021
Messages
3
Location
Longmont, CO
Doing a clutch replacement in my 90 YJ and the transmission is as dirty as a $3 lady of the night! Oil and grease everywhere. My biggest concern is that inside the bellhousing, all around the throw-out bearing and inside walls is a large amount of wet oil. When I pulled the bottom (driver side if it matters) bolt from the engine to the trans I actually got a couple of drips that came out. I would say it seemed more like a gear oil than engine oil, but who knows, its an old girl I just picked up and this is project 1.

Thoughts on where this is coming from? I dont want to throw a new clutch in it if its just going to get oiled up. Is this normal?

JP

20211001_231946.jpg
 
That's a mess!
Definitely not normal and you are right to be concerned for a new new clutch.
I'm not too familiar with the AX15 or where it might leak like that, given you think it's more like gear oil.
What does the back of the motor look like behind the flywheel?
 
Any or all of the three fluids in that area, Engine oil, Transmission oil, and clutch fluid.

Look at the forward side of the flywheel to see if it's wet. That would be the rear main engine seal. Not too bad to change if it's a 4.0L.

When you change the clutch slave cylinder (You will change it now right??) see if you can find a leak on the forward seal of the transmission. Also easy to change and might be worth the few bucks to do it now.

Other seals on the transfer case are easy too.

I think you would know if the clutch fluid is getting low over time to be leaking that much fluid.

A little oil goes a very long way with everything spinning around inside the bell housing.
 
  • Like
Reactions: jeepjoe43
I vote for transmission input shaft seal. Slave cylinder has brake fluid, that’s a light hydraulic fluid, engine oil you would know the viscosity of when you saw it. Originally the manual trans would have had gear oil.
 
  • Like
Reactions: Flyer58
Flyer58 said:
Any or all of the three fluids in that area, Engine oil, Transmission oil, and clutch fluid.

Look at the forward side of the flywheel to see if it's wet. That would be the rear main engine seal. Not too bad to change if it's a 4.0L.

When you change the clutch slave cylinder (You will change it now right??) see if you can find a leak on the forward seal of the transmission. Also easy to change and might be worth the few bucks to do it now.

Other seals on the transfer case are easy too.

I think you would know if the clutch fluid is getting low over time to be leaking that much fluid.

A little oil goes a very long way with everything spinning around inside the bell housing.
Click to expand...
I'm leaning toward the rear main seal, if the input shaft seal was leaking the splines would also be oily.
 
  • Like
Reactions: Flyer58 and ytradio
Is that what a 4.0 bell housing looks like? Much different shape than the AX-5 on a 2.5L. I'm surprised there's that big a difference.
No engine info in Juano007's profile that I found but he did say it's a 1990
 
Flyer58 said:
Is that what a 4.0 bell housing looks like? Much different shape than the AX-5 on a 2.5L. I'm surprised there's that big a difference.
No engine info in Juano007's profile that I found but he did say it's a 1990
Click to expand...
Yes, 2.5 has a GM bellhousing pattern which has the flat top with bolts at 11:30 and 12:30 vs 12:00. 4.0 has the old AMC bolt pattern which is rounded. The 2.5 starter also bolts to the engine whereas on the 4.0 it bolts to the bellhousing. Everyone always says the 2.5 is basically a 4.0 with two cylinders chopped off and while that is true for a lot of the engine, the rear end of both engines are very different from one another.
 
  • Like
Reactions: jeepjoe43 and Flyer58
Flyer58 said:
Is that what a 4.0 bell housing looks like? Much different shape than the AX-5 on a 2.5L. I'm surprised there's that big a difference.
No engine info in Juano007's profile that I found but he did say it's a 1990
Click to expand...
Did a '94 4.0 AX-15 swap from a '95 2.5 with a AX-5.....Really don't recall a huge difference between the bell housings other than how the starters were mounted....And the shifter port is brought back a couple of inches......
 
T-Rex Jeepster said:
Did a '94 4.0 AX-15 swap from a '95 2.5 with a AX-5.....Really don't recall a huge difference between the bell housings other than how the starters were mounted....And the shifter port is brought back a couple of inches......
Click to expand...


Somewhat subtle but it is there.

2.5/AX5
388_19a31a24-03bf-494b-8b26-f51c87f19d36_1024x1024.jpg



4.0/AX15
Mvtb5NSsT8O7bhskG0XakMQFEczmrrodxQFz=w1115-h836-no.jpg


The clutch release components (slave, fork, fork pivot and retaining spring, TOB) are the same, although the engines use different flywheels & clutches. The RMS is different on each (1 piece on 2.5, 2 piece 4.0) and pilot bearing is installed into the crank on the 4.0 and into the flywheel on 2.5. Nothing groundbreaking, but the differences are there.

I believe this all stems from the CJ days. AMC used the GM Iron Duke 2.5 back then which used that flat top bolt pattern. Then eventually they for some reason needed to phase out the GM engine and started with their version of a 2.5, and I'm guessing kept the same pattern so they wouldn't have to alter bellhousings. Not really sure but I know it all comes from them using the actual GM Iron Duke engine for a while in the older Jeeps.
 
  • Like
Reactions: Flyer58
Oh yeah.....AMC was notorious for "Borrowing" From other motor companies or adapting from existing lines rather than going through the expense/pain in the ass of Re-Tooling for a new product or variations to existing........
 
T-Rex Jeepster said:
Oh yeah.....AMC was notorious for "Borrowing" From other motor companies or adapting from existing lines rather than going through the expense/pain in the ass of Re-Tooling for a new product or variations to existing........
Click to expand...
Yup. Really the only thing that actually came from AMC and stayed a while was the 4.0 which came from all the other inline 6 iterations....and it had the AMC bolt pattern all along. I'll give them credit for their AMC20 axle although that died with AMC too since it was killed right before the YJ. Weird automaker for sure. Would have been interesting to see what AMC products would be like today were they still around.
 
  • Like
Reactions: T-Rex Jeepster
Jeep certainly has a colorful past with different and mixed OEM's, beginning with Willys subcontracting Ford in WWII.
AMC has always begged, borrowed or stolen from other OEMs', even provided to others when they were Rambler-Nash IIRC.

But with Cj's & YJs', where else can you find parts from all the big 3 in one vehicle?
Now when it came to making some of their own stuff in the '80's, I mean paper and cardboard parts? Really?
I liken those days at AMC to when AMF owned Harley-Davidson and nearly cratered the brand.
 
Top Bottom