Hi,


New to the forum, Cherokees and working on cars. Recently bought a 2000 Cherokee XJ, got a per-purchase inspection before hand and was told that front brake pads were good the rear pads were fine but would need to be replaced sooner rather than later. Started noticing vibration on braking and whirring/whining sound (two different sounds one happens on getting up to speed the other happens when I take my foot off the pedal and coast) only at 40 mph or higher. After doing some research I'm thinking it might be that the rotators are bad, or the bearings are not lubricated properly, or both. The car had been sitting for a bit at one point. I noticed that the rotator wasn't entirely smooth to touch and there was a little surface rust in that general area. I can send pictures if thats helpful. Just wanted to check if there were any quirks with the Cherokee related to these issues, and if there is any thing obvious I'm missing.


Also generally, are there any things that are generally good to replace, fix etc.? The mechanic on the pre purchase inspection was saying that doing the rear diff gasket, transmission gasket, rear main seal and oil pan gasket will have to be done at some point too. Any pointers, tips, post etc. on this topic or just generally, would be really helpful. (Already read the "now what" sticky and been going through the How To's on here.)


Thanks in advance.

 

It's pretty common for the wheel hub bearings (front) to go bad - especially if the axle nut is not torqued fully or it has been sitting for a while. It's not a difficult job to do yourself, if you've never done it before then you'll want to give yourself plenty of time.

The vibe on braking could be warped rotors or could be related to a bad hub.

The simple test to check the hub bearing is to jack the front up (you can put a jack or jack stands under the front axle tube part or the front diff as well as the frame rails) and grab the tire at 12 o'clock and 6 o'clock and wiggle it - it should have zero play. If there is play then almost certainly the hub needs to be replaced. If that checks out, spin the wheel and see if it feels rough or makes noise - also signs the hub could be bad.

If you do the Rear main seal, then you'd put a new oil pan gasket on at that time. It's common for folks to blame a bad RMS for oil leakage at the back of the block, but there are several other (much easier to fix) possibilities that need to be checked before dropping the oil pan and doing the RMS.
If you're comfortable with leaking a bit of oil you can drive quite a long time with a leaky RMS before it becomes a "fix it ASAP" situation.

 

Thanks for the detailed reply!
Are there any quick ways to rule out the rotator itself is bad as well? or do I have to pull the wheel off and check the rotator thickness and if its consistent throughout?
Also after reading what you said I did a little digging found that seems to be common precaution with the RMS on Cherokees, one post on here was saying check the valve cover gasket, oil pressure sending unit, oil filter adapter seals and distributor gasket. Gonna have to look up the location of all those haha. Anymore common ones, I missed?

 

Those are the oil leaks - Cruiser has a "standard post" that covers it. Valve cover is the top of the engine, sending unit is the little cylindrical thing near the oil filter and the oil filter adapter o-rings are on the thing where the oil filter mounts onto.

You have a 2000 so you actually don't have a distributor or distributor gasket. The 00 and 01 use a "coil pack" that sits over the spark plugs and an electronic sensor to determine ignition timing.

 

Alright got it, I'll check out the post.
Thanks again!

 

Anytime!

 

( I apologize if this would be better suited as a new post) Finally got around to bring in my Jeep to the mechanic, to get the sounds checked out, apparently my rear diff has gone bad The strange thing is when I changed the rear diff gasket and added new fluid, I didn't see and metal bits etc. But I guess I didn't address the leak quick enough to prevent permanent damage. The hydraulic fluid needs to be flush, and in the rear I need to change the brakes and potentially the rotators too. I'm wondering since a rear diff rebuild is quite expensive would my time and money would be better spent, replacing the rear axle all together since there are a number of issues. From my research online the cheapest option (at least initially) is to just find another XJ in a junk lot and pull the rear axle off that one and replace it. I was wondering if it was worth upgrading the rear axle since the Dana 35 seems to be quite disliked (though I'm using this car mainly as a daily its also RWD lol). Also are there any major concerns with going the rebuild route? Since the rear diff is already damaged would it be more likely to break again if repaired?
Thanks in advance.

 

imo, the cheapest & best option is probably to grab a Chrysler 8.25 from a later XJ wreck

a used Dana 35 will almost certainly need a rebuild anyway, unless its already had one

pretty well every old XJ leaks oil like a bastard from O-rings behind the oil filter adaptor, parts are cheap, but need a big Torx bit & some ingenuity, its tight from factory loctite

 

x2 on getting a Chrysler 8.25"

A differential rebuild will be expensive fast - just the bearing kit and labor will put you at a few hundred. If you need a ring and pinion (they are matched, so you must replace as a pair), then the parts are expensive - and if you need the gears too, then you're well over $1000 and possibly 2k.

If you can get a decent, low mileage C8.25, it's a better axle and you might be able to find one with reasonable brakes on it and you will only pay a couple hundred for the axle from a normal junkyard. If you do it yourself, it's not that hard a job (not that it's easy) and doesn't require specialized tools or expert knowledge.

 

Alright found one from 2001 on pull a part. I'll check it out hopefully its not too far gone. For the 8.25 is there anything I should look out for, weak points? or things to swap out before I swap it with my current one?
As far for the oil leak. At this point I've just been checking my oil weekly making sure color and level are good, so far they are the same the mechanic seemed to make it sound like the leak was serious but, on close inspection I haven't seen much. I'm changing the oil every 3000 miles, as per the owners manual. Also the levels have not been dropping. Is there a warning sign that would indicate the leak is an asap fix?

 

If you're not having to add oil, then you have a long way to go before fixing the leak becomes critical. Many folks happily drive around for years with a little bit of oil leaking.

You will want to get the rear driveshaft from a C8.25" with the same configuration (meaning automatic vs. manual, 2wd vs 4wd) since they are different lengths. It doesn't have to be off of the same vehicle, but I'd look for 97+ since (at least on the 4wd) the output shaft setup was changed. I don't know if they're all compatible or not. For the driveshaft, it would be nice if the u-joints were in good shape so at least you can change them or put off changing them as you see fit.
New rear driveshafts are available as well if you can't find one and can be found for about $100-150 for a regular-duty aftermarket branded part.

 

Ok makes sense. I'm also getting a bit suspicious of the mechanic I took it to. I might get a second opinion from a mechanic my friend recommended. I'm assuming its possible that if the rear diff went the bearings and u joint might also have gone, but is it possible that this could just be the bearing? the mechanic didn't pop the diff cover, just checked the fluid level, and pulled off the wheel and brakes etc. From some quick research I'm seeing that bad bearings generally produce a roaring noise, in the same way a bad rear diff would? I think I've determined I've got bad bearings, are there any dead give aways of a bad rear diff? Just want to avoid pouring time/money into the rear diff if it can be fixed more quickly. I might be just grasping at straws haha

 

Before you replace your rotators, make sure your wheel lug nuts are tight.

 

That's a good question - isolating the possible problem area - perhaps someone more knowledgeable than myself can answer.

As far as things in the rear diff, you have pinion bearings, (the yoke part that comes out the diff to connect the driveshaft), carrier bearings (on the diff gear assembly) and wheel bearings (in the axle tube that support the axle shafts).
You can easily disconnect the rear driveshaft and check out the u-joints (and isolate the shaft from the axle for diagnosis).

Being you have a D35, you have a weak axle that is prone to failure - including the diff gears breaking apart etc.)

I can tell you my own experiences -- I have a C8.25" on my 95 and I have a very slight noise, it sounds like a bad bearing. I took my Jeep to a 4wd shop that specializes in Jeeps - it's all they do - to have them diagnose the issue and give an overall look at it (I've done a ton of stuff myself, but I'm not a pro mechanic.) They said the noise was the diff, but without opening it up, they couldn't give me an idea of exactly what it would need. They immediately told me that it may be easier and cheaper to find a good, low mileage axle.
I told them to go ahead with a rear diff fluid change so they could check out the gears and a few minutes after hanging up the phone they called back and said that in the opinion of their diff expert, that the noise was common in the C8.25" and was probably not worth doing anything about - it will probably drive fine for years before I'd have to do anything about it. (So they could have taken my money on the diff fluid change, but didn't - plus they're respected and we'll known, so very trustworthy guys.)

Now I have the C8.25 and can live with a little noise from the axle - if I had a D35, I'd replace it under the same conditions.

 

How bad is the noise. Does it get louder with throttle at about 30mph?...an old un-rebuilt D35 will have all bearings worn anyway, to test if its the wheel bearings, jack it up..SAFELY, run rear wheels at roadspeed, you can usually hear where the bad bearing is

99.9% you will have a bad oil leak at the o-rings