Tony the Liger

Just bought a '00 XJ w/176k miles. Had it since Saturday, looked it over as thoroughly as I could prior to purchase, and didn't notice any issues when I bought it (PO could've wiped it down first, though). I took it out this morning, and when I got home I noticed a plate-sized wet spot where it'd been previously parked. Looked under it where it sat, and sure enough there was a fresh spot of oil (or something dark and oily, anyway - I know next to nothing).

Whatever the fluid is, it's dripping from the bottom of the front diff and the shaft going into it from the back. It's sat for close to two hours now, and doesn't seem to be actively leaking as it sits.



You'll see two drips on the bottom of the diff, and one on the shaft.

Any thoughts?

Also, while I was looking for the source of the leak, I found this:




Somehow overlooked that prior to purchase.

One end of that hose runs into the top left of the diff, and the other snakes up behind the engine and connects to...nothing. It's just stoppered and sort of tucked under another cable. So while a gaping hole would seem like an obvious source of fluid, I'm not convinced that that's where it's coming from (but, again, I'm learning and starting from ZERO, so I could be wrong).

Thanks in advance.

EZEARL

Your leak could be gear oil,engine oil,or both. If it's engine oil do this to determine the source:
http://cruiser54.com/?p=96

Your second pic is the differential vent. You need to replace the hose and there should have been a plastic check valve at the other end. If not get one at the local parts place. Take the old hose with you. And before you install the new one make sure the hole it connects to is open.

Tony the Liger

Wrt to the oil leak, does this look like a major issue, or just run-of-the-mill part replacement/maintenance? And when working backwards from the valve cover gasket, is the idea to replace each part one at a time until the leaks stop, or to open her up to find signs/a source of a leak? And how does one determine which part is the culprit? I'm sure I'm asking a lot, but I'd like to learn this stuff* so that I can adequately identify issues, as opposed to letting a mechanic run wild.

*Is there a decent resource you (or anyone) would recommend for someone looking to learn?

As for the vent, there is a check valve at the top end. When you say "hole it connects to is open," are you referring to the entry point on the diff cover, in which case open would mean "not clogged," or does it actually have a mechanism that opens and closes? Or, are you referring to the check valve?

Thanks very much for your time and info.

EZEARL

Anything you need to know or how to do can be found by searching online. Lots of info and how to videos. Never start by replacing parts at random. Also ask questions here no matter how "dumb" you feel they are. A good way to start learning is by scanning through the threads here at CF and anything that catches your interest read it.

First off clean as much of the oily area as you can. You can start your repairs by doing two things. The vent hose first. If you want to go ahead and clean that check valve. Or just replace it. You should be able blow through it from the end that's in the hose but not blow back through it. Make sure the hole in the differential isn't clogged. Only the hose connects there. Next replace the valve cover gasket. Use nothing but this gasket:
http://www.rockauto.com/en/moreinfo....363384&jsn=436

The vent hose fix isn't complicated. For the valve cover gasket just you do tube videos on how to do it until you find one you like.

Once your done you'll have more of a chance of seeing where your leak is coming from. Good chance that most is the valve cover gasket. Just the nature of the 4.0 in the XJ.

Read this thread when you get a chance:
https://www.cherokeeforum.com/f2/033...ould-i-234687/

Tony the Liger

Fantastic. Thanks very much. So you do you think a valve cover gasket replacement is necessary? I'm fairly confident I can do that.

EZEARL

With a flashlight look as best you can between the back of the valve cover and the firewall. Run your hand down in there too. If it's oily you'll have you answer. Is it wet around the sides of the cover where it fits on the head. Make sure if you watch a video they give the torque specs and tightening sequence.

You pics look like mine. I've got a new gasket sitting in the garage to put on before winter.

Also as far as buying parts? This is a great site. Even used by our local mechanics around here.
http://www.rockauto.com/

Tony the Liger

Oh yeah. It's oily. Guess I'm ordering a valve cover gasket. Thanks for the parts site recommendation, too.

EZEARL

No problem at all.

Tony the Liger

Just to help clarify (or further complicate) the issue, take a look here:


This is the stain left behind after I parked it earlier this morning (when I discovered the issue). Smaller than the next one, but the fluid was darker and thicker.

Later this evening, I started it up, reversed about 10 feet, and in the time it took me to stop, put it in drive, and roll forward, this occurred:


This time, though the stain was larger, the fluid was much thinner and clearer - though still dirty and with a very greasy feel.

FWIW, it only seems to leak if it's running.

EZEARL

Well you know you've got oil as far up the firewall as the back of the valve cover so you need the v/c gasket. If it's is bad enough it will leak out as the engine runs washing down who knows what with it. Remember Cruiser's link saying how this engines tilts down toward the back. Just keep your eye on your oil level.

bad_idea

If it is dumping that much fluid in 10' (running maybe 10 minutes?) then you need to fix that ASAP! Just driving it to work may be enough to run low on oil and damage the engine. Replace the valve cover gasket, wipe the engine down good (engine degreaser and a garden hose isn't a bad idea), then add an UV dye to the oil (google it, watch a youtube video even). At that point you will run the jeep long enough to observe the leaks, preferably in a dark garage or at night. Wearing the special glasses and black light you can observe the path the oil is leaking from. Most every oil leak on the engine can be fixed at home cheap. Some gaskets take more time to change due to all of the interferences that must be removed and reinstalled.

I suggest you also check the fluid level in the front differential. The shaft sticking out of the back of the differential is the pinion shaft. It is attached to the driveshaft. The pinion shaft has a seal around it that is prone to leaking. Checking the fluid level in the front differential is easy enough. There should be a threaded plug in the front of the cover that a 3/8" ratchet should fit in. Pull the plug, fluid level should be about even with the bottom of the hole. If low, add fluid until it drips out of the fill hole.

My 90 looked like the Valdez oil spill under the hood. It was everywhere! The PO added a quart of oil once a week. 80% of the leaks were from the valve cover gasket. It is commonly accepted that Jeeps leak, but pissing fluid is unsat. At the very least, adding fluid often gets costly in the long run. I spent most of the first six months chasing leaks. It still leaks, but nothing major.

Tony the Liger

Thanks for the info.

I still can't quite put my finger on the larger, wetter spot. Just doesn't look like oil, but it feels greasy and looks dirty. And it has mostly dried since yesterday; still visible, but not nearly as dark. If I'd been using the A/C, I'd be fairly confident that it was just drainage, but the A/C isn't all that cool* so I haven't even used it in the few times that I've driven the vehicle.

I checked all the fluids, and other than the oil being just a little on the low side, everything else appears to be okay. Not sure if any of that changes anyone's opinion about what's going on, but just thought I'd throw it out there.

*The A/C isn't a huge concern since we're on the back end of summer, and I knew going in that a cold-blowing XJ is kind of a rare bird these days. I don't feel pressed to get that looked at any time soon, UNLESS it's either a.) a symptom of something more urgent, or b.) something that could eventually cause a bigger issue. Are either of those scenarios possible? And, when the time comes to fix the A/C, what's the most common process for tracking down the issue? Recharge it and see what happens, or do XJ owners typically have to replace the compressor?

5-Speed

I skimmed through this so dont know if anyone has mentioned it but if its leaking that much, that fast, it could be coolant. I would fire the Jeep up, let it idle, lay under the front and wait for it to leak. You should at least be able to see where its coming from. Maybe not the main spot but close enough to point you in the right direction. To me, those spots you posted pictures of look slightly green.

EZEARL

My server won't download complete pics. If you say it's slightly green and he says it's got a greasy feel it could be a combination of oil and coolant. Got that freeze plug just below the back of the valve cover.

Tony the Liger

Nothing green about anything that's dripped from it, thus far. I've got a friend coming over in a few, so we're going to put both sets of eyes on it while it's idling, then I'm going to have him watch for me as I roll around the driveway. Gonna see if we can get a better read on things.