Got a ZJ for the woman...Questions...

[kyamcalvert]

So I picked up a '96 ZJ Laredo w/4.0/42RE ( I think?) for a really good price last week. Has 130k, brand new tires, a stack of receipts up to my neck, a boatload of new parts, and IMMACULATE interior (with working A/C!). Outside ain't too bad either. Pretty good for a 3 digit price. I'd post a pic if it wasn't in my dingy old garage. PO owned the truck since about 2001 and had a lot of proof that he did at least a decent job with upkeep. He and his wife had just got 2015 Chevy cars and considered the Jeep worthless, I think. Some people. Their loss is my gain! My problem now! etc etc etc...

Anyway, it was dumping a good bit of fluid from the back of the trans, so I pulled the 242 off, power washed the heck out of it, replaced the fluid, and replaced the trans output and tcase input seals. Threw new u-joints on the driveshaft for the heck of it, bought a trans filter and pan gasket, and am now considering getting in there and replacing the rear main seal while I am at it. It leaks about a quart every 2500 miles, but as it's going to be daily driven by a woman who normally has 2 small children yelling at her from the back seat, I'd like it to NOT do that. I'm not a mechanic, I do all my stuff DIY 'cuz I'm just a rebel like that. I am definitely confident in my ability to do the job, but would like some tips from the masters. I know to be careful enough not to mar the crank up and whatnot. I can't find a Haynes manual at any local parts shops and I don't really have the extra coin to grab the TSM just yet. Anyone got good torque specs for the bearing caps and oil pan bolts and stuff?

Also, there was a new oil pump in the parts pile he gave me. No idea why, nor did he really explain. Sort of said his dad thought it would be a good idea but that it was beyond his ability to replace it. I've owned/driven/worked on a few 4.0's and don't really seem to recall oil pumps being a problem area. Should I leave that whole situation alone and just replace the seal?

Thanks in advance!

[WaggyGuy]

Rear main replacement on the 4.0 isn't too bad. Drop the oil pan (messy), pull the rear bearing cap and replace the seal. Button it all back up and you're done. The hardest part when I did it was getting the old, baked, nasty oil pan gasket off. Take a look at this, it seems to be a decent write up for doing what you want to do:

http://jeep-xj.info/HowtoRearMain.htm

I would go ahead and replace the oil pump while you've got the pan out. Even though it isn't a common issue, you're going to have access to the oil pump anyway. Get a new screen and pick up if you don't already have one. As for the Haynes or Chiltons manuals, you can order them online and get them fairly quickly.

[carnuck]

I would ensure the CCV system (like earlier PCV setups) was working before opening up and doing the rear seal. If it clogs, pressure build inside and forces oil out, even past good seals. The oil filter housing Oring also tends to leak.

PS: Got a ZJ for the woman (Good trade, eh?)

[WaggyGuy]

Carnuck makes a good point. You might also want to verify that it is the rear main. While a rear main leak in a 4.0 is fairly common, it is also common to have a leak at the rear of the valve cover. That oil will leak straight down and look like a rear main leak.

[Stuka]

In the cases I have had to deal with, its the back of the valve cover, not the rear main.

[kyamcalvert]

Valve cover gasket is about 3 weeks old.

If only it were that simple

[csuengr]

Just be sure to get the one piece gasket for the pan. Makes life so much easier.

[kyamcalvert]

I would ensure the CCV system (like earlier PCV setups) was working before opening up and doing the rear seal. If it clogs, pressure build inside and forces oil out, even past good seals. The oil filter housing Oring also tends to leak.

PS: Got a ZJ for the woman (Good trade, eh?)

I laughed at this a bit longer than I probably should have....

Any tips on checking the CCV stuff?

[Stuka]

Just be sure to get the one piece gasket for the pan. Makes life so much easier.

Yes, this 100%

The multi-piece one sucks and is a pain. The single piece rubber one is so much nicer.

[kyamcalvert]

I have the one piece gasket. Twas included in the deal. Har har

[carnuck]

Pull the CCV hose at the cover and see if there is suction with the motor running to test it. I clean mine out with sensor safe cleaner once a year, On the earlier ones I also clean out the MAP sensor line if it's remote mounted. It's too bad you didn't know the screen under the valve cover gets clogged now and then or you could've checked it while the cover was off. You can blow through the line towards the valvecover to see if it's clogged at least.

[kyamcalvert]

Crankcase vent is fine. Valve cover screen did not feel clogged and the system was pulling good vacuum. I am about 90% certain the oil filter housing is leaking, so I will remove that and replace o-rings when I get a chance.

[carnuck]

I have it on good authority that the factory Oring set is best.