Rear Main Seal Might Be Leaking. Might Stop-Leak Help?

Wild Weasel · Feb 23, 2020

Hey guys,

I think my rear main seal might be leaking. It's a 2015 JKU with manual transmissions. I've got something leaking from the gap in the bell housing where the two round plugs are.

I thought at first that it was the clutch slave cylinder as I've replaced it twice in the past few months and though I might just be having horrid luck.

Now I'm not so sure. It's leaking a fair amount and my clutch fluid isn't going down. It's tough to really tell but I think it's oil. It's more brown than clear.

Trying to diagnose it, I cleaned the whole area and then let the Jeep idle in the driveway until I saw it start pooling up and dripping from the opening, so it's not running down around the transmission from the top. I've read plenty to suggest that could be the case from a cracked filter housing or something. I'm certain it's coming from inside the bell housing. Not around it.

Is there anything else I can do to diagnose it? Is there anything other than oil from the rear main seal and clutch fluid from the slave cylinder that would leak out there?

And if it's the RMS, could something as simple as stop-leak actually cure it? And is that stuff safe for the rest of the engine or is it a bandaid that would do more harm than good in the long run?

And if I have to replace the RMS... is that expensive? Anyone done it in Canada recently? I'm wondering if it's a few hundred bucks or if it's significantly more.

H8SPVMT · Feb 23, 2020

It could be the RMS or, the area around the RMS like the upper oil pan seal.
I have the extended warranty and had to have my RMS replaced twice before it stopped leaking .... and then it was the upper oil pan leaking around the rear main seal. They screwed the gasket material up I think and created a leake that shouldn't have been there.

leroybrown · Feb 23, 2020

It’s worth a try. Go to your parts store and buy two cans, give it a double dose and hope for the best. You have nothing to lose, and money to save if it works!

zimm · Feb 23, 2020

Please don't dump stop leak into your oil. Who knows what it'll do to all the good seals. If the rear main is leaking, the solution is to drop the tranny and fix it.

Read this and scroll down to where it says stop leak won't work on main oil seals anyway.

https://themotorsmasters.com/do-oil-stop-leak-additives-work/

Wild Weasel · Feb 23, 2020

Thanks guys. Looks like stop-leak isn't worth the potential issues it can cause.

Is replacing the RMS a huge job? I can't seem to find any clear instructions for this. I've found some suggestions that it's very expensive and others that say you don't need to drop the tranny and that it's done from within after taking off the oil pan.

YnotAJeep · Feb 23, 2020

Stop leak works by causing seals to swell. All the seals. A temporary fix at best.

YnotAJeep · Feb 23, 2020

I replaced the RMS in a chevy V8 many times and finally got it right. Remove pan, remove the rear main journal, carefully tap out the upper part of the seal without hurting the crank. Carefully install the new upper 1/2 and install the lower 1/2 in the journal, apply sealant and install. Not sure the 3.6 is the same and hope i never find out.

zimm · Feb 23, 2020

That's because your Chevy had a 2 piece oil seal. The 3.6 is one piece, so the transfer case, transmission, and clutch all have to come out. Then pull seal, replace, and put everything back.

YnotAJeep · Feb 23, 2020

Wow, didn't know that. So you can add the driveshafts and flywheel to that list along with probably a lot of other stuff. Bummer.

twistedoak · Feb 23, 2020

first thing i'd do is make damn well sure its not the oil cooler .
its burried and real hard to see anything visually.
take a long parts grabber tool with a claw on the end
put a piece of shop towel on it or oil pad
and snake it down into the valley.you can get it in around a foot with probing

if it comes back dry ,only then would I look elsewhere

Wild Weasel · Feb 24, 2020

If this is the source though, would it be leaking from within the bell housing or would it be dripping around it from up top?

roadrunner58 · Feb 24, 2020

If your oil cooler is leaking oil would be dripping down from up the top of the engine.

BlueBabySound · Feb 24, 2020

I've had 2 Jeeps with rear main seal leaks (2013 at 3k miles and 2014 at about 40k miles) and 1 Jeep with the oil cooler leak (2014 around 85k miles). From underneath the Jeep they both look the same.

Might be worth it to double check your diagnosis :thumb:

Wild Weasel · Feb 24, 2020

I went underneath and cleaned the whole area. I wiped down the sides of the outside of the bell housing really well. Everything was clean.

Then I started the Jeep and let it idle for a while. I revved it up few times to bring the oil pressure up.

Then I got back underneath it and burned my arm on the exhaust.

Then I watched as the oil pooled up and dripped out of the opening. Both sides of the outside of the housing stayed clean. The oil definitely came from inside.

This is also why I eliminated the clutch slave cylinder as a suspect. I didn't use the clutch during this other than to start the motor.

Jay2011JK · Feb 25, 2020

IMO. I would do the inspection that twistedOak noted in their post.. its easy - done and you won't burn your arm on the exhaust.. Cost to do is 0.00. BTW.. if it the cooler you might see the oil in the valley with a flashlight.

Wild Weasel · Feb 25, 2020

I did look around the oil filter cap with a flashlight and couldn't see much. I saw a bit of wetness on one of the wire looms that's right beside it but it didn't look fresh and could have just been a bit of spillage from the last oil change or something.

I'll definitely try with a reacher-grabber and some tissue before I go spending money on a repair though, just to be sure.

Also, I plan to tape some tissue to the two sides of the transmission on either side of the gap and then watch for it to pool and leak just to be absolutely sure it's not coming from the sides. I'm pretty confident... but hey... better safe than pissing money away on an unnecessary repair, right?

space-ghost · Feb 26, 2020

if it turns out to be the RMS, will answer any questions you have. Replaced it last year. To be honest I can see it leaking again though. One thing I really pay attention to is my oil level. When I change the oil I keep that oil level just below the top mark.

So far so good...

Lotrat · Feb 26, 2020

The oil pump on my 2016 failed and the dealer replaced it under warranty. They did a crap job putting it back together. They bent the pan and slapped RTV all over the place. Mine was dripping out the clutch vent too. Got tired of the drips and pulled the lower pan and re-torqued everything. There are 2 bolts up in the bell housing that hold the upper pan on. You can see one in the attached photo. Those were really lose and the source of my drips.

Wild Weasel · Feb 26, 2020

Well this is interesting!! I never thought to actually look up in there!

Was it literally leaking from around the bolt? So you could see it there if that's the issue?

gat · Feb 26, 2020

I seem to remember something about a dye that could be added to oil and then checked with a uv light to find the source of the leak.
I "googled" dye to find oil leak and got a $hitload of hits. Amazon sells it cheap as well as a uv light.
the seal (rms) is cheap. it's a lot of work to get it out and replace it.
good luck.
:beerdrinking:

Wild Weasel · Mar 3, 2020

Weather has been miserable lately so I haven't been able to look at it. Could they come loose on their own somehow though? I had the Jeep in for service and they replaced the oil pressure sensor (probably unnecessarily but that's a different story) just a few weeks before this leak started but there's no reason to remove the oil pan for that repair.

In the meantime... as they say... as long as it's still leaking oil... it's still got oil.

Lotrat · Mar 3, 2020

I would check the sensor they replaced. I could be leaking up top and finding it's own path down to where you are seeing it. Unfortunately, it's under the intake manifold.

Wild Weasel · Mar 4, 2020

Lotrat said:
I would check the sensor they replaced. I could be leaking up top and finding it's own path down to where you are seeing it. Unfortunately, it's under the intake manifold.

Once the weather cooperates and I can get back at it, my first step will be to make absolutely sure, without a doubt, that the oil is not leaking around the engine from the top. I will tape some tissues to the sides and get a video of it leaking out the opening just to remove all doubt from everyone here that's still not convinced.

RobertPWills · Mar 3, 2020

Discovered Same Issue Today After 5 Hour Drive

I just got back from Wheels and Water Show in the Panhandle of Fla- about a five hour drive back to Kissimmee.
When I disconnected my trailer, the safety chains were damp and oily.

I immediately got under my '14 Sport and saw that the underside was coated evenly in oil. I never got a warning light or temp issue. So that's good.

In any case- I'm trying to confirm- there's a second oil pan gasket above and inside the one around the pan itself?? Or am I misunderstanding?

I have never had my oil pan off- I'm at 60,000 miles. I replaced my tranny/transfer/diff oil two months ago and the undercarriage was clean and dry then.

THe last oil change was at Napleton Jeep in town last month- it it were leaking then, they would have been sure to upsell me something.

gat · Mar 4, 2020

RobertPWills said:
I just got back from Wheels and Water Show in the Panhandle of Fla- about a five hour drive back to Kissimmee.
When I disconnected my trailer, the safety chains were damp and oily.

I immediately got under my '14 Sport and saw that the underside was coated evenly in oil. I never got a warning light or temp issue. So that's good.

In any case- I'm trying to confirm- there's a second oil pan gasket above and inside the one around the pan itself?? Or am I misunderstanding?

I have never had my oil pan off- I'm at 60,000 miles. I replaced my tranny/transfer/diff oil two months ago and the undercarriage was clean and dry then.

THe last oil change was at Napleton Jeep in town last month- it it were leaking then, they would have been sure to upsell me something.

another advantage of flow thru lubrication - helps prevent undercarriage corrosion

RobertPWills · Mar 4, 2020

Changing Jeeps name to Leaky Tiki...

I've got oil puddled up top in the valley so it looks like that for me as well.

Called Napleton here in Kissimmee- the service guy said "I've got another 2014 in here right now with that problem- I can tell you exactly what it will cost to fix.- $1100.

And if I'm going to spend $400 in parts (about what it looks like), then I might as well pay them to do it and get a 2-year warranty on it.

Wild Weasel · Mar 4, 2020

Is this what you guys mean by checking the valley for oil?

I got as far in there as I could and poked around and the paper towel bit came up dry. It's a little dirty but there's definitely no pool of oil down there.

The middle pic is upside down, but you get the idea.

twistedoak · Mar 5, 2020

I myself would probe deeper.
esp since you now mentioned that they replaced the oil sensor.

if I had to target a spot, it would be near where the orange tape is on the wire harness.
if you slide down the side of the oil cooler body pushing rearward, there are spots it will drop into the valley .on both sides of the cooler
keep probing and you'll eventually find an area it will drop down way in.like 12-14" from the oil filter.

from the pics you only swabbed the top of the cooler

H8SPVMT · Mar 5, 2020

There are two things that could be leaking.
1 Rear Main Seal (RMS)
2. Upper oil pan. Yep there are two upper and lower. The upper is like a skirt that comes down from the engine case to form a place at the bottom for the little oil pan with the plug for draining the oil.

The upper oil pan seals under the Rear Main Seal like the old days but it does so very differently. The RMS bolts onto the outside of the engine and the bottom seal is made with sealant between the RMS and the flat matingof the upper oil pan lip.

Pictures are worth a thousand words in the case. After replacing 2 RMS a 3th was replaced after the upper pan was removed and sealed all around. Seems the mechanic distrubed the sealant on the upper oil pan, causing the lead.

Wild Weasel · Mar 15, 2020

Thanks for all the help here so far, everyone!

I'm continuing this saga in another thread so hopefully people searching in the future will find it helpful. This is definitely no longer about whether or not stop-leak might be a good idea.

Quick preview: Oil is definitely coming from inside and I stripped both the upper oil pan bolts that are up through the holes in the bell housing.

Please continue the relevant discussion here:

https://www.wranglerforum.com/f202/upper-oil-pan-might-be-leaking-stripped-bolts-2394853.html

Rear Main Seal Might Be Leaking. Might Stop-Leak Help?

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