My friends 97? Cherokee AWD axles get very hot. Any ideas as to what may be causing that? No noise and fluid levels are correct.

 

Found this from the jeep horizons website for causes of axles overheating. " Lubricant level too low, incorrect grade of lubricant, contaminated lubricant, bearing preload too high, excessive gear wear, insufficient ring gear backlash"

So what does bearing preload too high mean. Or insufficient ring gear backlash.

 

Check your owners maual and check the lubricant your cherokee requires.

 

The bearing pre-load is the amount of load(I.E. torque) it takes to turn the bearing while under no load with just the gears and bearings spinning...

Insufficient ring gear backlash is refering to the amount of movement the ring gear is moving back and forth under a pre-determined load setting...

Personally, when was the last time the gear oil in the axles was changed and what was the condition of the gear oil...was it milky(water intrusion), was it burnt(smelled like burnt cooking oil or worse), or did it have metal shavings or particals in the oil(would be signs of ring and pinion failure/damage or even bearing failure/damage). These are all things to look at when trying to determine the cause of the axles overheating..

Change the gear oil 1st, then work on it from there!!!
Gear oil is Cheap!!!

 

My friend dropped the truck off at my house. The gear oil is black and looks old.. can't say it smells burnt, but idk. The level was low. The rear diff has a rubber plug instead of a bolt to check the oil? Not really sure what to do with that.

He told me it does hum when driving. And I guess it overheated and sent oil all over the bottom of the jeep through the pinion seal.

 

THe rubber plug is the correct plug for the chrysler 8.25 diff cover, just a way to get around spending the extra dollar or two on a true plug. That is the correct plug. If the oil is black than it is deff time to change and put in fresh gear oil!!! If it had a burnt smell you would not be saying IDK, you can smell it a mile away or for days after you get it on you, it never seems to go away!!! The humming is probably from the fluid level being low and the gears whining while driving due to lack of fluid.

 

Ok so how do I tell if the truck has Trac-Lok? Do I need a new rubber plug if I remove it?

 

Don't rip it when removing and it shouldn't need replacing. I wouldn't drive it anymore till u fill the fluid. Even then It might need a rebuild. If u have spider gears in there don't us trac lok, just fluid

 

Do not need a new rubber plug if removed correctly! To tell if it has a Trac-Lok, you should jack the truck up on one side in the back(axle) and leave the other tire on the ground, try to spin the wheel that is in the air...If it spins it has an OPEN differential, if it does not spin, it has a Trac-Lok or some kind of Limited Slip or locker installed...

 

Ok so the fluid in there smells like it was burnt. Gears all look good. I'm gonna add fluid once the rtv sets.

 

Did you get the problem sorted out?

I knew you would smell the burnt smell, if it was there, it is an un-mistakeable smell...

 

Changed gear oil and front diff gets very hot still. Lots of noise. Do I need to adjust the preload and backlash, install a new pinion bearing, or buy a new front axel?

Can I use a regular 4x4 axle on this AWD truck?

 

Is this a Grand Cherokee with a 4-hi and 4-lo as the only choices of the transfer case shifter? I didn't realize they made an XJ that was AWD.

 

If it is still getting hot and making noise, it is probably bad bearings...

If you can do it and have the knowledge, change the bearings, but you will basically need to check the pre-load and backlash after. Probably won't change but you want to be safe..

Other option is to find the front axle out of a junk yard and just swap it in!

Also, Find out what front axle(probably D30 HP), and check on here in the wanted threads, someone is bound to have something that will work.