Oil Leak and Degreasing

Serbonze

Serbonze

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So I'm on to the next phase of working on the Jeep, and that is locating the source of an oil leak that appears to be getting worse. I always thought that I had a small RMS leak, but after some searching the consensus is to start from the top down and start with a check for a valve cover leak first. I checked last night, and the back of the block appears to be fine. However, when I got right up on the oil pan with a flashlight I was able to see a faint oil trail coming down the side of the pan and then collecting to form a drop right at the drain plug bolt.

Following that trail up and forward, it appears that the oil leak starts in the middle of the pan on the drivers side. There is quite a bit of gunk built up in that area, but from my visual inspection it looks like it is traveling back along the pan and then dripping down the side and also back to the bell housing, then dripping down and collecting right at the RMS.

So the point of the post...

I would like to degrease everything to really find the source of the leak, not just where I think it is. I think I first need to knock out the big chunks of accumulated oil/dirt, so I was going to do that with a brush and rags. There seems to be a myriad of suggestions when it comes to the actual degreasing. I've read warm up the engine and hit everything with Simple Green and then hose it off, I've read using Gunk and then hosing it off, I've read use a pressure washer, I've read to never use a pressure washer.

What's the best method?
 
The best method I've ever found for removing grease is steam cleaning. I got one of those smaller steam cleaners you use for clothes and I use it under the car. You've got to hold it there for a while but that thing gets rid of all the grease and then some!

The next best method I have found is simple green and a rough cleaning tooth brush (the kinds they sell at auto stores). Spray some simple green (mixed with water) on there and scrub the hell out of it with the toothbrush. That always does a damn good job!

Last but not least, have you considered putting UV dye in your oil so you can track the leak much easier?
 
I have used the coin-op pressure soapy sprayer on my engines many times over the years with good results. Just use common sense and avoid things like electrical connectors, sensors on the throttle body, etc. with the high pressure spray. It's ok if they get wet, you just don't want to hit them directly with high pressure. The only time I had a minor problem was when the engine had a distributor cap and water made its way up inside it which caused a minor temporary misfire that went away in a few miles as the moisture evaporated. That would not be an issue for your 2001 which does not have a distributor cap.
 
The 4.0 is notorious for loose oil pan bolts. I had to check mine every time I changed oil and always found some that had loosened up.
I use a pressure washer on the really dirty stuff, but make sure I keep it off the wiring harness/connectors and off all electronic stuff.

I use this stuff directly as a foaming spray and as a pure liquid in the parts washer. Much more harsh than Simple Green so use rubber gloves if you use it

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Thank you all for your replies...

Chris said:
Last but not least, have you considered putting UV dye in your oil so you can track the leak much easier?
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I have not tried this, but like I said I'm just starting the process of tracking down the leak. If I can't find the source, I will definitely look at this option.

Jerry Bransford said:
I have used the coin-op pressure soapy sprayer on my engines many times over the years with good results.
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You know, I've spent so many years cleaning and detailing my own cars I completely forgot about those!

Stinger said:
The 4.0 is notorious for loose oil pan bolts. I had to check mine every time I changed oil and always found some that had loosened up.
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Thank you, I will definitely check those when I get home. I know that there are two bolts right at the back of the oil pan, but there is a hard rubber gasket type thing covering them. I suppose that had to be removed somehow in order to check them?

I like the idea of the spray booth at the car wash, that keeps all of the crap off of my driveway. I can also use the simple green in conjunction with their sprayer and washer.
 
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I checked all of the oil pan bolts and they were tightened to the correct torque specs. While I was under there I used a stiff bristle brush and got rid of most of the big chunks of gunk. I'll degrease this weekend.

I'm still kind of hesitant about it not starting. :(
 
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While you are under there check the oil pressure gauge sending unit. Right rear of the engine. I had two fail on me. In fact, I started carrying a brass plug so when the next one fails and starts dripping oil all over I can remove it and slap the plug in there until I can get a new one.
 
Stinger said:
While you are under there check the oil pressure gauge sending unit. Right rear of the engine. I had two fail on me. In fact, I started carrying a brass plug so when the next one fails and starts dripping oil all over I can remove it and slap the plug in there until I can get a new one.
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Right rear...I assume you mean passenger side? Sorry for the clarification.
 
I just finished cleaning everything up. No oil leaks from the passenger side. I'll watch it carefully over the next couple of days to see where it starts. The good news is that it started right up. :)
 
Lol...the good thing is that it's started every time since that one non-start after I installed the starter.
 
Damn 4.0s and their oil leaks, LOL! My TJ had a small leak from the rear main, and my LJ has one as well. You just can't win with these things.

And don't even chime in with the "my V8 doesn't leak" @Stinger... We're all jealous :D
 
Chris said:
Damn 4.0s and their oil leaks, LOL! My TJ had a small leak from the rear main, and my LJ has one as well. You just can't win with these things.

And don't even chime in with the "my V8 doesn't leak" @Stinger... We're all jealous :D
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Now why would I ever say what is already obvious? Everything else leaks but.........
 
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Okay, so oil has shown up again. It's not on the side of the oil pan like I thought. It showed up on the bell housing, and it looks like it begins at the starter. Does the RMS leak from behind that plate on the bell housing? Is that why I can't see the source?

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Right above the starter is the oil pressure sending unit. Mine failed and slowly dripped down and collected on the bellhousing. Took me forever to find it.
 
I checked the sending unit again and it looked fine. I think I figured it out though. It's flowing down on the lip of what looks like a outer piece of a two piece cover on the bell housing, following the line below.
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Looks like the rear main seal might be leaking a little. Mines doing the same thing. I have an 05 with 2.5l and 6 speed. I was under it the other day and noticed it was seaping oil around the dust cover/inspection plate. Guess I'll pull the trans here in a couple of weeks and put a rear main in it and a new clutch while I'm there


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Serbonze said:
I checked the sending unit again and it looked fine. I think I figured it out though. It's flowing down on the lip of what looks like a outer piece of a two piece cover on the bell housing, following the line below.
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Mine had literally the exact same leak, in the exact same place. Turned out to be the rear main (go figure).
 
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