rear main seal leak?

Germanshepherd

Germanshepherd

TJ Enthusiast
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is this what this is? looking at the photo (looking under jeep from passenger side) to the left of the oil pan is a drip of what looks like oil at the bottom of the transmission? I think that is the transmission but not sure.
the drip is hard to see on this photo but its there and there is about a 2 inch diameter spot on road below the drip.
its dripping where it looks like that plate is bolted to the transmission. fluid is not red/pink but looks like oil to me but I also dont know the condition of my transmission fluid (color wise).

i have 161k miles on the jeep, 5 speed. any idea what this leak is and if it is a RMS leak, would high mileage oil help? thats what I have in it now, mobil 1 high mileage. thanks

IMG_20161005_185339871.jpg
 
Chris said:
Definitely your rear main seal, I'd bet on it. Very common on these 4.0 engines, but also not to difficult to fix.

High mileage oil won't help any unfortunately. Your best bet is to just fix it.

Check this thread out:
Jeep Wrangler TJ 4.0 Rear Main Seal Replacement
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thanks Chris... looked at that write up and is beyond the scope of my capabilities, but good to know its not too difficult for a mechanic. I have a really good and honest one so next time I have it in for something will get this fixed.
will keep an eye on my fluid levels.
 
Germanshepherd said:
thanks Chris... looked at that write up and is beyond the scope of my capabilities, but good to know its not too difficult for a mechanic. I have a really good and honest one so next time I have it in for something will get this fixed.
will keep an eye on my fluid levels.
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Keep an eye on it. I drove with mine leaking for 20k miles without any issue. As long as it's not spewing oil, you'll be fine. Just remember to check the oil on occasion and top it off.

The good news is that since it's a relatively easy job, most mechanics won't charge you for more than 4-5 hours tops. My friend had his replaced on his 4.0 engine in his XJ by a mechanic who specialized in Jeeps. He only charged him 3 hours of labor, so it came out to like $300. Not that bad if you ask me!
 
Chris said:
Keep an eye on it. I drove with mine leaking for 20k miles without any issue. As long as it's not spewing oil, you'll be fine. Just remember to check the oil on occasion and top it off.

The good news is that since it's a relatively easy job, most mechanics won't charge you for more than 4-5 hours tops. My friend had his replaced on his 4.0 engine in his XJ by a mechanic who specialized in Jeeps. He only charged him 3 hours of labor, so it came out to like $300. Not that bad if you ask me!
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thats good to hear. it took me over 20 years to find an honest and good repair place. there were many times they could have charged me for something when nothing was wrong. My mom on many occasions when she was drivng said the brakes were not working right. said the brake pedal went to the floor board. I found nothing wrong with it but took it to my repair shop and told them what she said.
they called later that day, said they checked it over thoroughly and said they could not find anything wrong and they did not even charge me. they said we did not want to go replacing things that were fine. I know every other shop I would have gone to in the past would have "fixed" something and then charged for it.

every time I take it in for inspection it always passes. most places say you needed something.
I had two leaks from two of my tires, took it in to them, they fixed it and did not even charge me. not even 1/2 labor rate. love that place.

back to my RMS. I never noticed it leaking before until I put in mobil 1 high mileage in it about 1k miles ago but I only had the jeep for about 1k miles so could be coincidence. I still have enough mobil 1 to do another oil change so will use that up and maybe consider trying something else if cheaper.
 
Yes, I agree, it's very, very hard to find reputable mechanic shops. This is why so many mechanics have a bad reputation. Most of them will charge you for the stupidest little thing, and even if they don't find something wrong, they'll still "fix" something as you mentioned. It's nice to have a good mechanic that you can trust.

The Mobile 1 high mileage must just be a coincidence. The 4.0 simply has a bad rear main seal design. I've seen them leaking with as low as 50k miles on them. Like I said though, it's fortunate that it isn't like most engines, which would require dropping the transmission to access the rear main seal. I'd say that kind of makes up for the crappy design!
 
Chris said:
Yes, I agree, it's very, very hard to find reputable mechanic shops. This is why so many mechanics have a bad reputation. Most of them will charge you for the stupidest little thing, and even if they don't find something wrong, they'll still "fix" something as you mentioned. It's nice to have a good mechanic that you can trust.

The Mobile 1 high mileage must just be a coincidence. The 4.0 simply has a bad rear main seal design. I've seen them leaking with as low as 50k miles on them. Like I said though, it's fortunate that it isn't like most engines, which would require dropping the transmission to access the rear main seal. I'd say that kind of makes up for the crappy design!
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You don't have to drop the trans but you do have to get the exhaust crossover head pipe from the manifold to the cat off and out of the way. Depending on condition, that may not be easy. I've had to cut some in front of the oil pan and weld them back together because that was easier than anything else.

After that it is just basis R&R until you get to the RMS and if you don't know how to cut the shoe out of a plastic water bottle, you can cut part of the outer edge off which may cause a leak.

The biggest issue with RMS repairs is there is nothing you can do better to ensure that they won't leak. Myself and a few others in the area that can be convinced to do them for folks will not guarantee they won't leak right away after doing one. I've never had one leak in short order but there is nothing I can do to make sure of that, so I make no promises.

If that rig in question were mine, I would get the Mobil 1 out of it right away, swap in some dino and see what happens. Certainly cheaper than paying someone to do a rear main when it may not be needed.
 
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Also worth a minute to take a peak at your valve cover as a leak from there can and will look very much the same as a leaking RMS.
 
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mrblaine said:
You don't have to drop the trans but you do have to get the exhaust crossover head pipe from the manifold to the cat off and out of the way. Depending on condition, that may not be easy. I've had to cut some in front of the oil pan and weld them back together because that was easier than anything else.

After that it is just basis R&R until you get to the RMS and if you don't know how to cut the shoe out of a plastic water bottle, you can cut part of the outer edge off which may cause a leak.

The biggest issue with RMS repairs is there is nothing you can do better to ensure that they won't leak. Myself and a few others in the area that can be convinced to do them for folks will not guarantee they won't leak right away after doing one. I've never had one leak in short order but there is nothing I can do to make sure of that, so I make no promises.

If that rig in question were mine, I would get the Mobil 1 out of it right away, swap in some dino and see what happens. Certainly cheaper than paying someone to do a rear main when it may not be needed.
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So am I wrong in thinking that the rear main seal on the 4.0 is a poor design? It sure seems that way.

I've heard the same thing that you said from a lot of professional Jeep mechanics. They too will say that they can't guarantee a new rear main seal won't leak after installing it.
 
Very true. I've heard when the rear of the valve cover leaks it can appear to be the rear main.
 
Germanshepherd said:
oh, by the way. with moms car, she was hitting the gas pedal, not the brake pedal. that is why it went all the way down. she did not drive the car when that happened but called me. we no longer let her drive.
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I do not allow my Mother to drive either. She insits that she's fine, but with neck surgery coming up it 2 weeks, she can't even turn her head. She drove 20 miles to my house last week, I almost lost my mind.:BangHead:
 
Chris said:
So am I wrong in thinking that the rear main seal on the 4.0 is a poor design? It sure seems that way.
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I'm not enough of a gear head to know either way but it is a common problem which would point to there being some issue with the design. The only saving grace is they are accessible without dropping the trans and pulling the crank.

I've heard the same thing that you said from a lot of professional Jeep mechanics. They too will say that they can't guarantee a new rear main seal won't leak after installing it.
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I do my best to avoid doing them and even tell folks I don't want to do them that and the amount of time it takes to deal with the exhaust isn't pleasant.
 
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FYI, I had a small oil leak like you describe on a previously owned 2003 TJ w/160k+ miles. The shop I took it to replaced the valve cover gasket first, then I drove it for a while...turned out it still leaked, so RMS was next. That seemed to take care of the leak, although I talked to the new owner and the small leak might be back.

Nature of the 4.0L beast...?
 
Definitely the nature of the beast. However, like I said, if the rear main seal is only dripping a few drops every week on your garage floor, all you need to do is worry about topping the oil off every so often. Unless it's leaking huge puddles, there's nothing to really be concerned about.

I think anyone who has owned a 4.0 long term has likely accepted the fact that the rear main seals on these things are constantly leaking. Of course, you may get lucky and get a rear main that doesn't leak for 150k. It's not unheard of!
 
Chris said:
Definitely the nature of the beast. However, like I said, if the rear main seal is only dripping a few drops every week on your garage floor, all you need to do is worry about topping the oil off every so often. Unless it's leaking huge puddles, there's nothing to really be concerned about.

I think anyone who has owned a 4.0 long term has likely accepted the fact that the rear main seals on these things are constantly leaking. Of course, you may get lucky and get a rear main that doesn't leak for 150k. It's not unheard of!
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I was never too concerned, although I did have it replaced...my TJ X got parked in a gravel spot in front of my house, so the drip never really was too apparent. I would notice it more in the parking lot at work than anywhere else. The new owner isn't concerned about it either.
 
glwood said:
I was never too concerned, although I did have it replaced...my TJ X got parked in a gravel spot in front of my house, so the drip never really was too apparent. I would notice it more in the parking lot at work than anywhere else. The new owner isn't concerned about it either.
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That works. Mine is leaking too as we speak. Just got to get around to fixing it one of these days.
 
ok, I am not so sure its the RMS now. I was lookt at back of valve cover and there is some really black dirty thick oil gunk back there. the back rear bolt on passenger side was not very tight so I snugged it down, some others were not really tight either so snugged them down a bit (no torque wrench).
sprayed some degreaser all around and let it drip down (with the degreaser,its dripping at bottom exactly where it was dripping before) so I think it may be the valve cover areas/gasket that may be the source of leak.

I heard good things about ATP 205 resealer so would that be an option before removing and replacing the gasket? it supposed to be better than the and safer than the other stop leak products. its a clear liquid, unlike the other products that are oil based.
I hear the argument that if it plugs a leak it will plug things that are not supposed to be plugged but some products only target the seals and have no effect on any other openings.

I read tons of reviews on it and for most people it worked and did not see one bad review that said it hurt anything, just did not work for their particular leak.
worth a try? thx
 
Germanshepherd said:
I heard good things about ATP 205 resealer so would that be an option before removing and replacing the gasket? it supposed to be better than the and safer than the other stop leak products. its a clear liquid, unlike the other products that are oil based.
I hear the argument that if it plugs a leak it will plug things that are not supposed to be plugged but some products only target the seals and have no effect on any other openings.
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I can't speak on the ATP 205 since I've never owned it, but there's a crap ton of reviews here:
https://www.amazon.com/dp/B000NVW1LM/?tag=wranglerorg-20

I usually read the negative ones first, then focus on the positive ones.

Still, I wouldn't waste my time with a resealer. Doing the valve cover gasket on these things is probably one of the easier projects you could take on. I mean it's really, really easy. I'd just replace the valve cover with a new one and do it the right way the first time.
 
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