Groaning, grinding noise from rear.

[Jonathan Willis]

Hi, I have a 2002 Cherokee Limited KJ, 3.7L Automatic.
After a drive of half an hour or so, when pulling away, a groaning grinding noise can be heard from the rear of the Jeep. It's more pronounced when turning at the same time and can feel a slight vibration too.
There doesn't appear to be any play in the wheel bearings, pushing hard with my foot the wheels doesn't make any such noise and the centre of the wheels are stone cold.
I've had a feel of the differential cover and that feels quite warm. I was able to top up the differential with the correct fluid, it took just over a litre. I've not been able to get right under the Jeep to check the drive shaft joint yet.
The problem doesn't occur on short runs around town, only after longer trips.
Any help and advice much appreciated.
Thanks, Jon.

 

[Jonathan Willis]

Hi, I have a 2002 Cherokee Limited KJ, 3.7L Automatic.
After a drive of half an hour or so, when pulling away, a groaning grinding noise can be heard from the rear of the Jeep. It's more pronounced when turning at the same time and can feel a slight vibration too.
There doesn't appear to be any play in the wheel bearings, pushing hard with my foot the wheels doesn't make any such noise and the centre of the wheels are stone cold.
I've had a feel of the differential cover and that feels quite warm. I was able to top up the differential with the correct fluid, it took just over a litre. I've not been able to get right under the Jeep to check the drive shaft joint yet.
The problem doesn't occur on short runs around town, only after longer trips.
Any help and advice much appreciated.
Thanks, Jon.

I've had to write " pushing hard with my foot" because " hard " and "on " wasn't allowed.
What ever next ?

 

[tommudd]

Do you have limited slip rear diff ?
The fluid may need changed with correct additives
Also after driving it a while 20-30 mintes get under and put your hand on both u joints, if hot they are bad
Then also could be the emergency brake shoes that have came loose or worn out and grinding
Start there

 

[Jonathan Willis]

Do you have limited slip rear diff ?
The fluid may need changed with correct additives
Also after driving it a while 20-30 mintes get under and put your hand on both u joints, if hot they are bad
Then also could be the emergency brake shoes that have came loose or worn out and grinding
Start there

Thanks for the advice.
It may seem like a dumb question but how do I tell what kind of diff I've got ?

 

[tommudd]

The easiest way to tell if you have an open differential is to jack up the car and spin one of the rear tires. If the other wheel spins in the opposite direction, you have an open differential. If it spins in the same direction, you have a limited slip differential

Or submit your VIN and check that way, although if someone along the way have switched out the rear diff, then ....LOL
Like my 03 , I have had 3 ( plus the original ) rear diffs in it so far , due to building them ( gears and lockers ) , selling them , etc

 

[Jonathan Willis]

The easiest way to tell if you have an open differential is to jack up the car and spin one of the rear tires. If the other wheel spins in the opposite direction, you have an open differential. If it spins in the same direction, you have a limited slip differential

Or submit your VIN and check that way, although if someone along the way have switched out the rear diff, then ....LOL
Like my 03 , I have had 3 ( plus the original ) rear diffs in it so far , due to building them ( gears and lockers ) , selling them , etc

Thanks for your help, hopefully I'll get round to having a look this weekend.

 

[Mangate]

Taking a litre of oil to get to the correct level sounds worrying.

 

[EricNorton]

Check the rear pinion seal I had similar symptoms and it was because I was low on oil in the rear diff because my seal broke so my rear diff would catch and bind then free up causing me to increase the amount of pressure I put on the gas pedal. I was told is normal with lifted vehicles due to the pinion angle being increased which can increase pressure on portions of the seal.

 

[LibertyTC]

An open carrier does Not need an additive, however the limited slip or known as a Trac-Loc does require the 4 oz bottle of Mopar limited slip additive.
Type in your VIN # here https://fcacommunity.force.com/RAM/s/equipment-listing
& see if yours needs the limited slip additive. It should be listed in build sheet as Trac-Loc.
What weight/brand of gear oil are you adding? We recommend using DINO gear oil not synthetics.
Note the rear diff service requires removing the cover every 35-40 k miles. You can then inspect for wear & look for metal shavings on magnet.
It should be filled enough so that the level is just at the fill plug, with no more leaking out on level ground.
Is it leaking at the cover seal or pinion seal?
The 02 factory service manual can also help you. http://www.colorado4wheel.com/manuals/Jeep/KJ/2002JeepKJServiceManual.pdf

 

[Jonathan Willis]

Check the rear pinion seal I had similar symptoms and it was because I was low on oil in the rear diff because my seal broke so my rear diff would catch and bind then free up causing me to increase the amount of pressure I put on the gas pedal. I was told is normal with lifted vehicles due to the pinion angle being increased which can increase pressure on portions of the seal.

Thanks for your reply. The Jeep is the standard height but I will check that out, along with everything else in there.

 

[Jonathan Willis]

An open carrier does Not need an additive, however the limited slip or known as a Trac-Loc does require the 4 oz bottle of Mopar limited slip additive.
Type in your VIN # here https://fcacommunity.force.com/RAM/s/equipment-listing
& see if yours needs the limited slip additive. It should be listed in build sheet as Trac-Loc.
What weight/brand of gear oil are you adding? We recommend using DINO gear oil not synthetics.
Note the rear diff service requires removing the cover every 35-40 k miles. You can then inspect for wear & look for metal shavings on magnet.
It should be filled enough so that the level is just at the fill plug, with no more leaking out on level ground.
Is it leaking at the cover seal or pinion seal?
The 02 factory service manual can also help you. http://www.colorado4wheel.com/manuals/Jeep/KJ/2002JeepKJServiceManual.pdf

Thanks for your reply, we haven't had the Jeep long and I haven't had a chance to get the cover off yet. I did however lift the rear up and found that it is equipped with limited slip differential and I'll double check the fluid I've bought.

 

[Big Al]

I just recently bought my Liberty too and noticed a humming noise on the highway from the rear end.
Opened mine up and found the spider gears were a bit chewed up (spalling) like these pictures.
Need to change them out when I get around to it also.
Check for this when you open yours up.
Mine is a limited slip also.

 

[Jonathan Willis]

I just recently bought my Liberty too and noticed a humming noise on the highway from the rear end.
Opened mine up and found the spider gears were a bit chewed up (spalling) like these pictures.
Need to change them out when I get around to it also.
Check for this when you open yours up.
Mine is a limited slip also.

Thanks for your reply, looks like there's plenty to check out in there. Oh well, there's a first time for everything, just hope it doesn't cost too much.