Oil Leak

Whiplash2130

Whiplash2130

YJ Enthusiast
Joined
Jul 16, 2020
Messages
150
Location
Florida
Just got her back from the shop. Put on 150 miles. Then took her for a 60 mile trip.
Looked underneath 2 hours after putting her in the garage and there is a 10 diameter puddle of engine oil on my floor. Oil pan is wet mostly around the drain plug, but I can’t rule out a pan gasket leak. But what bothers me most is there is a plate that bolts between the engine and transmission seems to be very wet... rear main seal leaking???
 
Option 1: Find and fix oil leak
Option 2: Replace engine with remanufactured 2.5 L 4 cylinder
Option 3: Replace with 6 or 8 cylinder engine
What’s your opinion?
 
Mine has leaked since the day I bought it. I just park it over cardboard. Pretty sure I am dripping from the RMS and my distributor hole (2.5L) I haven't had to add any oil in 6 months of ownership. Its a 30 year old vehicle, a small leak isn't a lot to worry about unless its a pristine show vehicle. Just think about your oily film underneath as rust preventative and check it every once in a while to make sure it isn't low and you will be just fine.
 
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Tanker_01 said:
Mine has leaked since the day I bought it. I just park it over cardboard. Pretty sure I am dripping from the RMS and my distributor hole (2.5L) I haven't had to add any oil in 6 months of ownership. Its a 30 year old vehicle, a small leak isn't a lot to worry about unless its a pristine show vehicle. Just think about your oily film underneath as rust preventative and check it every once in a while to make sure it isn't low and you will be just fine.
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Like I said, just got it back from a shop that ran a dye through the oil system to find the leaks. They said it was only leaking from the valve cover and replaced it. Oil was topped off. 60 miles and I’m 1/2 a qt. Down with a puddle under the YJ. It definitely needs to be addressed.
 
Whiplash2130 said:
Like I said, just got it back from a shop that ran a dye through the oil system to find the leaks. They said it was only leaking from the valve cover and replaced it. Oil was topped off. 60 miles and I’m 1/2 a qt. Down with a puddle under the YJ. It definitely needs to be addressed.
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The RMS on the 2.5 goes bad a lot. If the leak forms at the top of the seal it will only leak when your engine is running. If its near the bottom though it will leak all the time. Mine is near the top I believe so it only leaks for a few mins after shut down. If you're leaking all the time it would be worth it to pull the trans back and replace the RMS. It isn't a huge job to do, there's a lot of room on these old jeeps to work on this stuff.
 
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Whiplash2130 said:
Like I said, just got it back from a shop that ran a dye through the oil system to find the leaks. They said it was only leaking from the valve cover and replaced it. Oil was topped off. 60 miles and I’m 1/2 a qt. Down with a puddle under the YJ. It definitely needs to be addressed.
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Also, if that shop wasn't able to diagnose that as the issue, I wouldn't go back to them ever again. That is why I do all my own maintenance... Probably was pretty expensive for them to replace the valve cover seal which is a $7 part you can replace yourself in about 10 mins.
 
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I’m retired and really don’t want to do the projects anymore, just want to drive and have fun. I’m still more than capable of doing it but... Then there’s the wife!!
 
Tanker_01 said:
The RMS on the 2.5 goes bad a lot. If the leak forms at the top of the seal it will only leak when your engine is running. If its near the bottom though it will leak all the time. Mine is near the top I believe so it only leaks for a few mins after shut down. If you're leaking all the time it would be worth it to pull the trans back and replace the RMS. It isn't a huge job to do, there's a lot of room on these old jeeps to work on this stuff.
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The RMS on the 2.5 is a one piece seal and rarely goes bad. The one that goes bad a lot is the 4.0 which is a two piece seal.
 
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I would bet on the really crappy stock cork valve cover gasket being the issue most likely. You may have an oil pan or RMS leak as well, but they are less likely.
 
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With the 2.5 the one piece rear seal may be easy for some but requires a lot more work. You need to pull the flywheel off to get to the end of the crankshaft. Installing the flywheel is tricky because they use stretch bolts which are torqued to 50ft/lbs then turned another 60 degrees. According to the factory service manual they're "suppose" to be a one time use bolts but I doubt many listen to that. I called the local dealership and they located the last 6 bolts for the YJ in the country at a little dealer in Michigan. I think I've read TJ bolts may work too but didn't verify that.

Unfortunately it's not a job I'd try lying on my back in the driveway like with the two piece seal.

Can you bring it back to that shop to verify the new valve cover gasket isn't leaking or maybe it's something else?

I had to rebuild my engine because the oil pressure sending unit failed and blew out all the oil. Unfortunately the previous owner didn't catch it in time. No oil is bad...
 
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Flyer58 said:
With the 2.5 the one piece rear seal may be easy for some but requires a lot more work. You need to pull the flywheel off to get to the end of the crankshaft. Installing the flywheel is tricky because they use stretch bolts which are torqued to 50ft/lbs then turned another 60 degrees. According to the factory service manual they're "suppose" to be a one time use bolts but I doubt many listen to that. I called the local dealership and they located the last 6 bolts for the YJ in the country at a little dealer in Michigan. I think I've read TJ bolts may work too but didn't verify that.

Unfortunately it's not a job I'd try lying on my back in the driveway like with the two piece seal.

Can you bring it back to that shop to verify the new valve cover gasket isn't leaking or maybe it's something else?

I had to rebuild my engine because the oil pressure sending unit failed and blew out all the oil. Unfortunately the previous owner didn't catch it in time. No oil is bad...
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Jeep is back in the shop. The replacement bracket for the transfer case shift linkage came in, but before that, they will change out the oil pan to a new one I bought and change the rear main seal. This is not the same shop that did not find the leak in the first place, this is a transmission shop. They should be used to properly changing out a seal. Fingers crossed!
 
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Whiplash2130 said:
Jeep is back in the shop. The replacement bracket for the transfer case shift linkage came in, but before that, they will change out the oil pan to a new one I bought and change the rear main seal. This is not the same shop that did not find the leak in the first place, this is a transmission shop. They should be used to properly changing out a seal. Fingers crossed!
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I’d wait to have them do the RMS until after the oil pan and valve cover have been done. That’s a lot of work for something that might not be the answer. Pulling the oil pan does not make a lick of difference to the RMS replacement on a 2.5 so there is no need to just have them do it until you’ve ruled out the easier options first.

Otherwise, if you’re still going to have them proceed with the RMS, have them install a new clutch while they’re at it because there’s no reason not to while they’re pulling the transmission for the RMS.
 
As always, I appreciate your insight. I’m going ahead with the seal change now regardless of its current condition in order to increase the likelihood of it happening 3 months from now. As for the clutch, which was claimed by the previous owner to be brand new, I will look at it and change if oiled up by the rms.
 
Whiplash2130 said:
Option 1: Find and fix oil leak
Option 2: Replace engine with remanufactured 2.5 L 4 cylinder
Option 3: Replace with 6 or 8 cylinder engine
What’s your opinion?
Click to expand...
. My Rear Main Seal was leaking pretty bad, short video below. The clutch and pressure plate are in new condition and will be reinstalled. Hopefully with this and a new oil pan the oil leaks will be done once and for (all) a while!
894118C6-A08C-456B-B234-99D906496ACE.jpeg
5FCCF8C4-D063-4984-8C5B-29E94C8BE011.jpeg


 
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I am having a leak issue too. I have a 4.0L I6. I had to replace the oil connection switch because a good bit of oil was dripping on the ground from there. I fixed it, but my oil is still leaking somewhere. I don't see it drip anywhere, but I check my oil level before I drive. It may happen when I drive it. Could mind be the RMS as well? May my connector switch need to be a little tighter? The threads had the pre white thread locker on it out of the box. Thanks.
 
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I'd start by pressure washing the engine so its clean and you can be sure where the leak is .

Leak test it at idle so air doesn't blow the oil all around.
 
SirDoopYJ said:
I am having a leak issue too. I have a 4.0L I6. I had to replace the oil connection switch because a good bit of oil was dripping on the ground from there. I fixed it, but my oil is still leaking somewhere. I don't see it drip anywhere, but I check my oil level before I drive. It may happen when I drive it. Could mind be the RMS as well? May my connector switch need to be a little tighter? The threads had the pre white thread locker on it out of the box. Thanks.
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Don’t over-torque the sending unit! If leaking remove it, reseal and reinstall. There’s also a good possibility that the RMS is leaking. At the bottom of the bell housing there is a slot about 1” long, if you have oil dripping from there (after a good cleaning) it’s the RMS. I chose not to replace it myself. Good luck!
 
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