4WD will not disengage

[johntk]

1999 Jeep Cherokee Sport

My Jeep 4WD has begun acting strangely. It will not disengage when I push the handle down. It will drop back into 2WD only after I run it a few feet in reverse. Also, during 4WD travel I hear a whining sound. In addition, today I smelled an odor that made me think something was getting very hot. One more: when turning during 4WD the steering wheel oscillates back and forth. The car will turn, but it feels like it is fighting back.

I bought the car new and have used 4WD at least a few times every year since. I have never had any problem with it before and have kept everything maintained that I know about. The vehicle has approxiately 127,000 miles and has only been driven on paved roads (no off-road driving). There is no problem when driving in 2WD.

I'd appreciate any insights into what the problem is.

Thanks,
John

[fredjacksonsan]

Had any tire work done lately?

Reason I ask is that a difference in tire size (even same size tires but different brands) can cause what you are experiencing. If you have 2 tires that are worn and 2 that are new, replacing the 2 older tires with the same ones as the new ones would be my call.

If all your tires are the same, check the inflation levels.

As far as the vehicle fighting itself in 4wd on pavement, well, yes. It's a part time system and the front and rear driveshafts are turning at the same rate. When you turn, the outside front tire moves quite a bit further than the inside rear tire, resulting in the driveline binding up. Damage can occur, so turning on a non-slippery surface is not recommended (owner's manual has details on this).

So...check tire pressure, tire manufacturer and wear of all tires. You might get away with a tire rotation only, but can't know the answer to that until you have looked at them. Post back with the results and we'll try to help some more.


edit: another thought. At 127k, if you've never changed the transfer case fluid, that could contribute to it sticking in 4wd. Pretty easy job, just need some lube, something to pump it with, and the right tools to open up the plugs.

[johntk]

Originally Posted by fredjacksonsan

Had any tire work done lately?

Reason I ask is that a difference in tire size (even same size tires but different brands) can cause what you are experiencing. If you have 2 tires that are worn and 2 that are new, replacing the 2 older tires with the same ones as the new ones would be my call.

If all your tires are the same, check the inflation levels.

As far as the vehicle fighting itself in 4wd on pavement, well, yes. It's a part time system and the front and rear driveshafts are turning at the same rate. When you turn, the outside front tire moves quite a bit further than the inside rear tire, resulting in the driveline binding up. Damage can occur, so turning on a non-slippery surface is not recommended (owner's manual has details on this).

So...check tire pressure, tire manufacturer and wear of all tires. You might get away with a tire rotation only, but can't know the answer to that until you have looked at them. Post back with the results and we'll try to help some more.


edit: another thought. At 127k, if you've never changed the transfer case fluid, that could contribute to it sticking in 4wd. Pretty easy job, just need some lube, something to pump it with, and the right tools to open up the plugs.

Thanks for the info. I have not had any tire changes lately and just had the pressure checked a couple weeks ago. I will check again tomorrow just to make sure all is well. The tires have been on for a long time.
The transfer case oil may be an issue. I'm not sure I've had that changed - I'll see if I can find any record.
I know turning in 4WD is not as smooth as 2WD but this is much more pronounced than normal. Pavement was wet from melted snow, but not necessarily slick.

Thanks again for the reply, I'll do some checking and get back to you,
John

[fredjacksonsan]

In patchy snow I can see how you'd get the "herky jerky" feeling, as the tires slip and relieve the driveline windup on the snow, then start binding up again on the pavement.

What about tire rotation? If you have had the tires on the same axle their entire lives, then the fronts will be worn more than the rears and a rotation is in order.

Interested to see what you find.

[LittleHoov]

Definitely check your transfer fluid level.

Also, are you putting it into full-time or part-time 4wd?

The Cherokee had 2 different transfer cases during the biggest part of its lifetime, and they do have their differences, and quite honestly the sticky at the top of the page really only covers the 242, even though its titled 231/242. Plus it doesnt mention any of the cases used in the early year models, but I digress.

If you do have the 242 with the full-time setting, and everything is working properly, you should be able to run in 4wd even on dry pavement with no issues...this only applies to the full-time setting. If you try to run in part-time HI or LO on dry pavement, you can cause serious damage ro your drivetrain.