Jeep Wrangler Forum banner

New Jeep owner with 4.0 oil leak

37K views 17 replies 10 participants last post by  DOITHARD 
#1 ·
Hi all,
I am back to being a jeep owner. Haven't had one since my CJ7 in the late 80's but I have purchased a 2000 Wrangler Sport with a 4.0 manual and it is instantly bringing back many memories.
Ok, here's the problem. Small dripping oil leak from BOTH the flat surface of the rear part of oil pan and also from the lowest point of the bell housing behind the bell housing front shield. Oil was just changed so I can tell it is engine oil and not transmission oil although the oil coming from behind the bell housing plate is much dirtier, but it feels thin and not like transmission fluid.
I've wiped the back side of the valve cover gasket area to try to see if oil is coming from it and after driving it, that area seems to stay clean when I wipe it again with a clean paper towel.
I also sprayed and thoroughly cleaned backside of oil pan, plug and front of bell housing. It appears that oil is all on passenger side of top part of oil pan and runs down the flat back surface of the pan, but it also drips from behind the front shield of bell housing.
This leaves me 3 possibilities as I see it: valve cover gasket, oil pan gasket/seal or rear engine/rear main seal.
Bolts on oil pan felt tight.
From what I can see, it appears that the lower front shield of the bell housing somehow "lips" over and under the oil pan lip. I thought it had to be rear main since I was also getting oil dripping from behind the bell housing front shield, but the way the shield seems to go over and under oil pan lip, I guess it could be catching and transporting oil from an oil pan gasket leak to the bell housing....is that possible?
Or since if also seems to also be running down the inside of the front plate of the bell housing, does that confirm it is the rear main?
Any way to tell a rear oil pan gasket leak from a rear main seal leak?
Any way to confirm it may just be a simple rear valve cover seal leak besides just trying to wipe a clean towel back there since this seems to be the most common problem?
Ok, now more questions: I've had 2 repairs places tell me I had to drop the transmission to replace the rear main to the tune of $400-500. From what I can tell from what I see and what is on youtube, that is BS, you just have to drop the oil pan...correct?
Do you have to remove the exhaust where it crosses over to get the oil pan out and also the starter it looks like will also have to be moved...correct?
What should I expect to pay for a rear main replacement?
What should I expect to pay for a new oil pan gasket repair?
I can do a valve cover gasket replacement myself, but any special secrets to that on this engine?
Thanks
Suzy
 
See less See more
#3 ·
From what I understand, 4.0's may have either a one piece or a two piece rms
I suspect that you would have a very difficult time rounding up an example of a 4.0L engine with a one-piece seal.

Ok, now more questions: I've had 2 repairs places tell me I had to drop the transmission to replace the rear main...
Absolute poppycock.

I can do a valve cover gasket replacement myself, but any special secrets to that on this engine?
Felpro Permadry gasket.
 
#12 ·
1. A quick temp fix is always a bad idea.

2. Thanks to the chemical makeup of brake fluid, it is hygroscopic. So if you really want something in your engine that absorbs and retains water, then go for it. Otherwise, I'll stick to replacing the seal and using oil, which is made to displace water, which damages engines.
 
#5 ·
Just completed RMS on my 06 TJ w/a 4.0 and a 6spd manual. The rear main seal is not a bad deal to replace. I dropped the cats-back to allow better access to oil pan. I dropped tranny and t-case too but do not recommend this. BIG PIA. I had to replace clutch too as I burned it up not replacing rm sooner. I purchased a 2 piece seal as you will need to push the top half around the seat to get it out. I found a good link that I will look for but it suggested to by 2 kits in case you screw one up. I did and it was a big time saver. The gaskets are cheap. Take your time.
 
#9 ·
An RMS is $30 and an oil pan gasket is around $25. Do yourself a favor and replace both at the same time. You might as well, since an RMS will eventually go bad anyways, and either way you're going to be replacing the oil pan gasket. It takes $55 plus the cost of your oil/oil filter and about an hour of your time using nothing more than sockets, a punch and hammer(to carefully tap out the old RMS), a gasket scraper/razor blade, a piece of a drinking straw (to guide in the new RMS), and some dish soap to lube the new seal.

Simply drop the oil pan and go to town. At the very most, if you're having trouble getting the old seal out, loosen a few of the caps at the back of the engine to lower the crank a tiny bit.
 
#14 ·
That brace only needs to be removed in earlier model 4.0L engines. You shouldn't have to remove it. You don't need that gasket maker. I use soap to lube the seal and get it in place, as well as a piece of a drinking straw that is cut to act like a shoe horn.
When taking it out, I use a very small punch and a hammer, so you don't accidentally nick the crankshaft by accident. Just some easy tapping and it will pop out to one side, where you can grab it with some needle nose pliers.
He also used the RTV in the wrong places.
 
#15 ·
Be careful, with what you think. I had the same problem you did when I bought my jeep. I was ready to replace the rear main seal myself, and thought I'd look a little deeper. I was loosing oil too quickly. So, I replaced the valve cover gasket and in removal I found that it was improperly installed, it was resting on a ground cable bolt at the back of the engine near the fire wall. A little wiggling and got it on. And stopped loosing oil.
It continued to leak in the same spot you are talking about. Figured it must be the RMS. Looked again really hard and it had like a hairline crack in the head gasket. Leaked from above the distributor down the head to the back of the engine down to the oil pan and bell housing. Basically had to rebuild the top end of the motor and found out in 100,000 miles the PO never changed the oil ...so much gunk. :bang head: Even sent the head to a machine shop to have it checked for cracks.
Point is, check it carefully before you start replacing stuff. Brake clean removes oil really well to help you spot the issue. But be careful what you get it on, it can be toxic.
And not saying it is the head gasket cause my neighbor is a mechanic, on 4 wheel drives specifically and said in 20 years experience he's never heard of a head gasket breaking on a jeep. Guess I'm the first..:thumb: Hope my experience can help you.
 
#16 ·
Thanks everyone for all your help and input. It appears it is most likely the RMS from what you guys have stated and replacing that will also fix an oil pan gasket if that was the problem.
Although I am somewhat knowledgeable about engine mechanics and can do small stuff myself, there is no way I can do this repair myself. From what you all have said and what I have seen on youtube, the transmission does not have to be dropped.
I called 2 repair shops before I posted and both claimed the tranny had to be dropped and repair cost around $400-500. After reading your emails, I decided I would contact our local Jeep dealer to see what they said. The receptionist came back on the phone and said it would be $950 because they had to drop the tranny. I told her from my research that you could do it by just dropping the oil pan. She got snippy with me and said several of her service guys all said you had to drop the tranny. I said, thanks anyway.
Does the service code/shop manual call for dropping the tranny for a year 2000 model? Is this why all these shops are saying it has to be dropped?
So, I guess I am having a hard time finding someone who can do it for me without costing an arm and a leg and do it by dropping the oil pan.
Anyone know any legit Jeep mechanics in the Kansas City area????
Suzy
 
#17 ·
tangofox007 said:
I suspect that you would have a very difficult time rounding up an example of a 4.0L engine with a one-piece seal.

Absolute poppycock.

Felpro Permadry gasket.
X2 on the permadry

Thought I had a leaky rms or oil pan when I crawled underneath. Saw some oil on the back passenger side of the block so I did the easiest thing first and did a valve cover replacement, so far so good. Pretty easy and straightforward, the worst pain is the black electrical plastic( don't know what it's called) piece that runs over the rear of the cover.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top