Head Gasket or Rear Main Seal Oil Leak(s)

[W_A_Watson_II]

I have a very frustrating oil Leak on the 2002 Jeep Wrangler. I've replaced the valve cover gasket, rear mail seal and oil pan gaskets. Not saying that I got the rear main seal in correctly and leak proof, but here is my problem.

Some oil leaks out on the passenger side of the engine between the head and block (from the oil return galley).

I thought I had a leaking rear main seal after having replaced it already, so I started to replace it again, and found oil on the side of the engine around the oil filter. Thought it might have been the oil filter, so I cleaned the side of the block the other day and installed a fresh oil filter as well as the oil on the bell hosing.

Started the engine up on three different occasions after that, and let it run until it warmed up and no oil leaks. Took it out for a drive, and the leak is back. the side of the block is oily again, and the oil pan (except for the mount flange) is dry. The oil on the front of the trans dust shield is almost totally on the passenger side, while oil on it's back side is covering a larger area.

Based on the amount of oil it leaks I'd say it's more oil than the head gasket would leak, but the front of the flywheel is essentially dry.

The following links will show some pictures of the oil/engine. Any thoughts or ideas?

http://jeep.wawii.com/images/2002TJ/Oil ... 104517.jpg
http://jeep.wawii.com/images/2002TJ/Oil ... 104553.jpg
http://jeep.wawii.com/images/2002TJ/Oil ... 104621.jpg
http://jeep.wawii.com/images/2002TJ/Oil ... 104807.jpg
http://jeep.wawii.com/images/2002TJ/Oil ... 120900.jpg
http://jeep.wawii.com/images/2002TJ/Oil ... 160313.jpg
http://jeep.wawii.com/images/2002TJ/Oil ... 160449.jpg

[TSEJEEPERS]

What about the gasket for the thing that replaces the distributor?

[W_A_Watson_II]

That was my first thought today, it's a paper gasket, but their is no spray on anything, but oil from the head down.

[DanB]

Thought I had read about 4.0L leak
found it back of JP Mag Nov 2014 Your Jeep section
back of block behind flywheel loose plug on oil galley

[W_A_Watson_II]

Oh, gee I hope not.

With the flywheel essentially dry I'm leaning towards the rear mail seal still leaking.

[W_A_Watson_II]

Here are a couple of pictures from changing the 1st Rear Main Seal (VERY Large Pix):

http://jeep.wawii.com/images/2002TJ/Oil ... 1stRMS.jpg
http://jeep.wawii.com/images/2002TJ/Oil ... 1stRMS.jpg

[W_A_Watson_II]

Well, after doing a thuro cleaning and placing a piece of pig mat between the engine side and the lower area to isolate and oil leaking from the engine side from the bottom of the flywheel I ran the Jeep for 40 min.

I do have an oil seep along the head to block interface on the passenger side, but it's not the volume leak.

http://jeep.wawii.com/images/2002TJ/Oil ... 140550.jpg
http://jeep.wawii.com/images/2002TJ/Oil ... 140602.jpg

However the real leak does appear to be the RMS, or perhaps the pan to rear main cap. So it's time to drop everyhting again and replace the seal one more time.

http://jeep.wawii.com/images/2002TJ/Oil ... 140653.jpg
http://jeep.wawii.com/images/2002TJ/Oil ... 140914.jpg
http://jeep.wawii.com/images/2002TJ/Oil ... 141234.jpg
http://jeep.wawii.com/images/2002TJ/Oil ... 141243.jpg

[W_A_Watson_II]

I'm not sure what the "Book Rate" is for changing a Jeep 4.0 Rear Main Seal, but put me down for about 2.5 hrs, I'm getting better each time I do it. I also had a swivel 15mm socket this time rather than a swivel and a 15mm socket which helped.

Based on what I think I had going on was not what I'd expected. I thought maybe I'd installed the top half backwards, or the small piece of back side seal that shaved off when I slid the upper in was the culprit. Then once I had the Rear Main Cap off I looked everything over and noticed the passenger side seal lip was recessed as compared to the rest of the seal. Was it a bad seal, did I damage it? I looked at the new seal, and it's end cuts were also on a slight angle, so it must be done that way to keep the square end from getting pushed when the crank turns.

http://jeep.wawii.com/images/2002TJ/Oil ... 095247.jpg
http://jeep.wawii.com/images/2002TJ/Oil ... 095256.jpg

I pulled the upper and lower seals out and, well I think I know what happened. It looks like I was a little too liberal in the sealer I applied at the cap mating points and the material seeped into the lip void and might have "glued" them slightly open.

http://jeep.wawii.com/images/2002TJ/Oil ... 095403.jpg
http://jeep.wawii.com/images/2002TJ/Oil ... 101743.jpg

So I cleaned everything up very well and installed the new seals with liberal amounts of assembly lube.

http://jeep.wawii.com/images/2002TJ/Oil ... 104536.jpg
http://jeep.wawii.com/images/2002TJ/Oil ... 104639.jpg

With everything buttoned back up I let it set for a while before starting. Once started the oil pressure started to rise, I ducked my head underneath, and WHAT! Oil came out of the bell housing almost immediately and faster than before. Quickly shut off the engine grabbed a flash light and crawled underneath. No signs of where the oil came from, crank and flywheel were dry, nothing running down the inside or outside of the bell housing that I could see.

Started it up again and a little more oil then nothing. Let it run for a short period and then shut it off and cleaned all the oil up. Before starting the job I'd jacked the back of the jeep up and drained the bell housing out, but while changing the seal I only had the front of the Jeep jacked up. So the oil that ran out must have drained from somewhere into the bell hosing while I was doing the seal replacement and once I let the Jeep back down the air and vibrations forced it out. At least that's what I hope.

So I restarted and let it run for about 20 min. and ran it up thru some RPM's. All looks OK and dry, but I guess I won't know until I hit the road again, as that's what it took last time for the leak to appear. Wish me luck, please.

[W_A_Watson_II]

Well, took the Jeep to get Pizza tonight. About 5 miles each way, but should be a good quick test.

http://jeep.wawii.com/images/2002TJ/Oil ... 181844.jpg

It looks the Rear Main Seal is holding as I see no evidence of oil coming from it or it's location.

http://jeep.wawii.com/images/2002TJ/Oil ... 181956.jpg

However I still have some oil dripping from the bell housing. It looks to be coming out of the starter. How do you check the oil level and seals in a Starter?

http://jeep.wawii.com/images/2002TJ/Oil ... 182130.jpg
http://jeep.wawii.com/images/2002TJ/Oil ... 182153.jpg
http://jeep.wawii.com/images/2002TJ/Oil ... 182157.jpg

I'm not sure how much of the starter oil is residual, or just where it drips to from this leak. Does anyone know what the item is that's bolted to this stud in the head? In looking at my YJ's head, that should be a blind hole, and oil not able to get to it. But it sure looks like the oil is coming from around that stud. I'll pull it out, check it's depth, put sealer on it and re-install it and hope that takes care of it.

If anyone else has any ideas or clues please pipe up.

Thanks,
Will

[W_A_Watson_II]

Well, it looks like the Rear Main Seal is indeed now good. However when I pulled the stud out to check it for being the source of the leak, well it's not.

http://jeep.wawii.com/images/2002TJ/Oil ... 091615.jpg

So I cleaned it and the head to block seam again, and proceeded to externally seal it to help slow down the leak.

http://jeep.wawii.com/images/2002TJ/Oil ... 094606.jpg

Took it to do some shopping/shipping and Archery, and well, the head to block leak still is a nuisance issue. I'll re-clean and re apply as best as I can and live with it. I'm not yet ready to replace the head gasket.

http://jeep.wawii.com/images/2002TJ/Oil ... 154430.jpg
http://jeep.wawii.com/images/2002TJ/Oil ... 154619.jpg
http://jeep.wawii.com/images/2002TJ/Oil ... 154638.jpg