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Rear Main Seal - Advice

5K views 19 replies 11 participants last post by  adm793 
#1 ·
I just received a new to me, 2001 Jeep TJ about a month ago. I know the history as it has been in the family for the last 10 years and I know that it has been meticulously maintained over those 10 years.

After a recent 1600 mile trip, I noticed a good size drip from what appears to be the rear main seal area. Its not a small drip or seep, I left it parked this week on my driveway and it had about 1/4 quart of oil on the pan I placed under it. I have read the write-ups on the replacement and plan on performing the fix myself. However, before I dive in, is there anything I should be looking at as the alternative source of the leak or potential problems when opening up the underside.

The jeep is not my daily driver, so I am not stuck if "Murphy's Law" (Common for me) decides to pay a visit. I am just looking for any advice or experience from other Jeep owners.

Also - Off topic. The jeep has a hard top that I plan to remove as soon as I have room for parking the jeep in the garage. What's a fair price to ask for the top on my local CL. It was professionally repainted Black about 4 months ago and in excellent condition. If it matters, I am in the Orlando, FL area.
 
#2 ·
Sounds like a very significant leak. Other considerations would be leaking from rear of valve cover gasket and dripping downwards so it's reasonable to look for evidence of oil on your engine higher up on the block or cylinder head. Common things occur commonly though, so RMS leak is a legitimate suspect.
You haven't told us if your Jeep is 4 or 6 cylinder, the complexity of the RMS replacement significantly differs: You must pull transmission and flywheel for the 4 cylinder, but for the 6, you can just drop the pan. You've read about this process, so you likely know this already. Nice to have a torque wrench to properly torque the rear main bearing assembly bolts properly .

Hard top value in your area? Hard to say, since there is wide variation in various markets. Research various Craigslistings in your area and beyond and you can come up with a reasonable listing price.

Welcome to the Forum.
 
#4 ·
The rear main seal is common to seep on the 4.0L, to my knowledge, due to it being an older two-piece design. Someone please correct me if I'm wrong.

I replaced mine once it started to leave half-dollar size spots wherever I parked, and it started to seep within 10,000 miles of replacing it.
 
#8 ·
Its for sure oil. The jeep recently had an oil change and I have checked levels a couple times and it has continuously gotten lower. I checked the drain plug and cleaned off the area above the drain plug and I can see it leaking down from the RMS area. I haven't checked to see if it is coming from above the RMS area, but will look more closely this weekend. My driveway is on an incline and I spun the vehicle to see if the direction it was parked would make any difference on the leak. It didn't. The vehicle has not been driven since.

I updated the profile, but it is a factory stock 2001 Jeep Sahara TJ 5-speed. I assume it has the NV3550 based on some of the other information I have read on the forums.
 
#7 ·
Hard tops here run $600-800 in VGC. I sold mine for $500 just because I don't like them. There's no advantage to having one.
 
#9 ·
I agree. Its the reason as soon as I have room in the garage, the top will be sold, the full doors will come off and the carpet will be removed. I have wanted their jeep since the bought it, now that its mine, I will have to make it mine. I just need to stop/slow the oil leak first...
 
#11 ·
The jeep is not my daily driver, so I am not stuck if "Murphy's Law" (Common for me) decides to pay a visit.
Murphy's law is common to everyone, kind of the point Murphy's law is making. ;)

I used blue devil power steering additive on Boogiemans advice after having tried several other types of stop leak. Worked after just the first 3 ounce application. Before the application I was filling my power steering fluid weekly. Since the application I have not had a single drop escape and have not had to refill at all. (btw, huge thanks on that one Boogie :cheers2: ).

When I suspected my rear main seal was the cause of a very significant oil leak I decided that before going down that road that it might be rear of the oil pan seal itself that is leaking. I tightened up the bolts to spec and then used some RTV around the sealing area just as a test to see if I could stop the leak, not as a long term fix. Low an behold it was the oil pan itself. Turned out later I needed a new oil pan (had pinholes developing) and since I was having the clutch replaced a few weeks later i decided to do the RMS anyway (>250k miles on the engine so though it was a good idea while the tranny was out) but that is neither hear nor there. Might be worth checking for the same in your case. :dunno:

Good Luck. :cheers2:
 
#12 ·
I got back under the Jeep and took a better look. It's wet by the rear of the oil pan on the passenger side and the entire area around the RMS. The drivers side is drier than the passenger side. However, it looks more like a seepage and not full blown leak.

I checked the valve cover and its dry.

It still might be a simple oil drain plug contributing to the major leak. Do the drain plugs use a crush style washer? Is it possible that it was not replaced and or over tightened last oil change. I put a wrench on it and it's on very tight.

Now that it's all cleaned up, I'll re-inspect tomorrow morning.

The oil pan and valve cover seals where replaced in the past. I can see the blue after market seals typical of the Fel-Pro's. I'm gonna see if the shop that has been servicing it the last 10 years will pull up the service records.
 
#18 ·
I got back under the Jeep and took a better look. It's wet by the rear of the oil pan on the passenger side and the entire area around the RMS. The drivers side is drier than the passenger side. However, it looks more like a seepage and not full blown leak.

I checked the valve cover and its dry.

....
I assumed I had a RMS leak a couple years ago, until I bothered to test the valve cover bolts. I couldn't see it, but it was leaking oil down the back of the engine. Since tightening them, my Jeep does not leak even at 115k miles.
 
#13 ·
Based on the praise, I'm gonna have to check out the Blue Devil products.

I typically stay away from additives in the past, but my other vehicle has a very slow seepage on one of the valve covers. I would love a simple fix vs pulling apart half the engine to reach the valve cover. Even though I have the gaskets in the garage, I've been avoiding the fix for the last 6 months.
 
#14 ·
It is possible to leak from the oil filter, oil pressure sending unit, both on the passenger side. Your oil drain plug should be 1/2" X 20 TPI if you decide to replace it. I suppose it is best to rule out the simple things before digging into the RMS, it's kinda like something Mike Rowe should have a show about.
 
#20 ·
To each their own on the Hard Top. For me the Jeep is a 3rd vehicle for weekend fun and other outdoor trips. We have a SUV for the family, a truck for versatility and now a Jeep for fun. For me, the Jeep is my toy and the hard top and doors will be coming off as soon as the top is offloaded.

As far as the leak. I have found two different leaks since it was cleaned up and sat overnight. The first leak is coming from the drain plug. The second leak is coming from the RMS area or the rear of the oil pan. I put a Torque wrench on the rear oil pan bolts and one of the larger bolts was off by quite a bit. I'm holding out hope that it's the rear of the oil pan leaking and not the RMS.

After cleaning it up again and topping off the oil, I took it out for the day and let it sit overnight. A good sign is the oil spot on the drip pan has gotten smaller.
 
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