NAXJA Forums -::- North American XJ Association  

Go Back   NAXJA Forums -::- North American XJ Association > NAXJA Unibody Jeep Technical Forums > Jeep Cherokee XJ (1984 - 2001) > OEM Tech Discussion
HOME Member FAQ Sponsor Info Rules Bylaws E-Mail

OEM Tech Discussion Forum for OEM (Original Equipment) or stock XJs and MJs.

Reply
 
Thread Tools Display Modes
  #1  
Old January 10th, 2020, 14:00
bpatto10's Avatar
bpatto10 bpatto10 is offline
NAXJA Forum User
 
Join Date: Dec 2014
Location: knoxville, tn
Posts: 18
Question whine and rumble in overdrive (38-45), disappears at 55-60 on highway

Hello,
I have a 1996 Jeep XJ stock, 6 cyl/4.0 engine, 4WD, AW4 transmission, 231J transfer case and Chrysler 8.25 axle, with 245000 miles.

I get a rumble sound (wa-wa-wa) sound as soon as I hit 38-45 (i.e. overdrive) accompanied by a whining noise. The rumble and whine seem to disappear when I get in the 55-60 range. I really don't feel a vibration that correlates with the whine and rumble, other than the normal vibrations of a 20 year old vehicle.

The local Jeep dealer said it was my differential, rebuilt my rear axle, and the noise did not change at all. I was P.O'ed.

I can make the rumble sound almost completely disappear/reappear by shifting from OD to 3rd and back. The torque convertor was replaced last year.

Other places have told me its the transfer case (91K mile JY case), which I tend to doubt as I recently drained the fluid and it was perfectly clean. No silver or blackness at all. I do this every year anyway. Never saw a hint of silver. I am at a loss as to how a problem in the transfer case would be affected by OD.

Web searches almost immediately led to differential problems for these type of noises. One posting indicated that worn output bearing and/or planetary gears on the transmission could cause whining or rumble noises.

I don't mind replacing the aw4 or transfer case, but I want to make sure I am not overlooking something else or replace the wrong part.

Lots of Grand Cherokee owners complain about a rumble in overdrive at low rpm (such as going up a hill), and everyone says to just live with it.

The combination of whine and rumble is what concerns me.

Other than the noise it drives fine and shifts fine at all speeds and drives fine in 4wd (at low speeds on dirt roads).

Thoughts/suggestions on tests or other areas to check?

Thanks,
Bruce
Reply With Quote
  #2  
Old January 10th, 2020, 16:38
Tim_MN's Avatar
Tim_MN Tim_MN is offline
Freakish Hand Strength
 
Join Date: Mar 2003
Location: Minneapolis, MN
Posts: 7,115
Re: whine and rumble in overdrive (38-45), disappears at 55-60 on highway

Start with the common issues, and the easy/free stuff. Perform some diagnostics tests and some push/pull/wiggle checks.

How old are the u-joints ? Are the drive shafts still properly balanced ? Is the front slip yoke worn excessively ? What is the condition of the motor mounts and transmission mount ? When was the transmission fluid changed last, and are you using the recommended Dexron-III/Mercon fluids and not using ATF+4 ?

Have you removed the front driveshaft and taken a test drive over the same roads that cause the symptoms ? Now put it back, and remove the rear driveshaft and go for the same test drive in 4x4 Hi. When the driveshaft is removed, check the corresponding pinion for excessive in/out and/or up/down movement.

Most Dealerships know nothing about diagnostics, they are only interested in installing new parts.
__________________
.
.

Quote:
Originally Posted by bimmerjeeper


Go ahead and slam the liftgate down on a blanket, and see how long you are laughing.
Reply With Quote
  #3  
Old January 10th, 2020, 18:45
Anak's Avatar
Anak Anak is offline
Stranger
 
Join Date: Sep 2013
Location: In a strange land
Posts: 3,651
Re: whine and rumble in overdrive (38-45), disappears at 55-60 on highway

I will second the removing of driveshafts as above mentioned.


I will also add, pay real close attention the the centering ball in the front driveshaft. That part is often neglected when it should be serviced just the same as the U-joints.
__________________
Project "Scope Creep": 1996 4wd 4.0L, AX15

The "Varmint-Mobile": 1997 ZJ Laredo, 4wd, 4.0L, Slushbox
Reply With Quote
  #4  
Old January 29th, 2020, 13:46
bpatto10's Avatar
bpatto10 bpatto10 is offline
NAXJA Forum User
 
Join Date: Dec 2014
Location: knoxville, tn
Posts: 18
Some new information

Thanks for all the replies. I took out the front driveshaft and it made no difference. The rear driveshaft has new u-joints and was balanced about a year ago.

While thinking of new tests to conduct, I changed the spark plugs to RC12LYC as recommended in this thread:

https://www.cherokeeforum.com/f2/idl...00-rpm-250241/

As I expected, it did not make a difference, but the existing plugs had 20K, so it was not a loss. Before calling it a day, I started the engine and put it in neutral just to make sure I had no CEL. When I ran up the rpm, I could still feel the shudder mentioned in the other thread, and surprisingly, the shudder was much stronger as the engine coasted down back to idle. ???

I definitely have something in the engine area or engine itself that needs attention. Could it be possible that this engine problem is also the source of the rumble in the 40-55 range (overdrive) as the torque converter is now directly coupled to the engine?

I have almost convinced myself that the whine is due to improper gear backlash and setup, as I can not think of anything in the engine area that would cause it.

Thanks in advance for any further tests and suggestions.

PS: For the past several weeks, I have been reading threads about whine in the 45-55 mph range under acceleration. It is amazing how many owners of relatively new $30-50K Ford, Chevy, and Dodge RAM trucks are having to have differentials rebuilt or even whole axles replaced under warranty (or having to bite the bullet if outside of warranty) for this very problem.
Reply With Quote
  #5  
Old January 29th, 2020, 15:14
75SV1 75SV1 is offline
NAXJA Member
 
Join Date: Sep 2004
Location: Hope,IN
Posts: 575
Re: whine and rumble in overdrive (38-45), disappears at 55-60 on highway

Check the harmonic balancer. See the recent thread on that. At that mileage, I'd change it an ways.
Reply With Quote
  #6  
Old April 19th, 2020, 17:11
bpatto10's Avatar
bpatto10 bpatto10 is offline
NAXJA Forum User
 
Join Date: Dec 2014
Location: knoxville, tn
Posts: 18
Re: whine and rumble in overdrive (38-45), disappears at 55-60 on highway

Quote:
Originally Posted by 75SV1 View Post
Check the harmonic balancer. See the recent thread on that. At that mileage, I'd change it an ways.
Thanks for the harmonic balancer tip. I looked at it after your post and did not see any in/out motion while running, so I thought that it was not the problem.

However, last weekend while crawling around under the jeep to investigate the source of an very small oil leak, which I assumed was the valve cover since it was appearing on the front bell housing cover plate, I noticed the harmonic balancer was beginning to shed rubber, and the area around it was covered in a thin layer of oily dirt.

Sure enough after replacing it and the front seal, the vibrations while revving the engine in idle disappeared, as well as my oil leak.

I still have some vibrations from the engine, as I can see my drivers side door vibrating slightly while in idle, but it is much better.

The whine and rumble are still present at the 40-60 mph speeds, but I am beginning to wonder if this is not engine or engine accessory related as well. I will continue the investigation.

A belated thanks for the suggestion.
Reply With Quote
  #7  
Old June 16th, 2020, 17:22
bpatto10's Avatar
bpatto10 bpatto10 is offline
NAXJA Forum User
 
Join Date: Dec 2014
Location: knoxville, tn
Posts: 18
Re: whine and rumble in overdrive (38-45), disappears at 55-60 on highway

Okay, so I am narrowing this thing down. No change if I remove the front driveshaft. I bought a infrared thermometer reader from Amazon and tested the differential after an extended 55 mph drive. Temps are in the 130-140 range at the pinion snout, which I think is very good. The front is in the 100-120 range. The rear driveshaft was balanced and new u-joints installed before the tests.

I removed the rear driveshaft and the whine and rumble both disappear completely even at the 45 - 55 mph range. So, in my mind, this eliminates transmission gear whine/wear, and front wheel hub bearings, and only leaves transfer case and differential. Since it does not make the sound in 4wd with the rear driveshaft, I am thinking most of the transfer case must be okay, and the problem is probably in the rear output bearing, since it would have no load with the rear driveshaft removed, and of course load with it installed.

If I were getting higher rear end temps I would have suspected a bad rebuild job, but with the high level of whine and rumble at 50 mph, I don't think I would have such low temps if the differential were the source.

The only concern I have is that I don't see any metal shine when I change the transfer case fluid.

So any thoughts? Anything other possible sources that I should consider?


Two funny side stories:


(1) After reading numerous web articles on similar symptoms, I had totally convinced myself that it was a bad wheel bearing, even though the present ones only have about 15K on them and they passed the tire twist test, the swerve side to side test and the "hand on the coil springs" while turning the tires test. But removing the rear drive shaft and not hearing the whine at the 45 mph point where it always previously started shot that theory down cold.

(2) I stopped at a local garage based on a recommendation from a fellow jeeper I met at Pull-a-Part. He had a lift kit installed by them and gushed over their "jeep guy". So, I stopped by and had their "jeep guy" take it for a short spin. He came back and immediately showed me a 3d infrared temperature scan of my rear axle. It of course showed the pinion area as the hottest area with a bright white color. It looked bad, and then he said "the differential is overheating, it is reading 130 in the pinion area". He immediately starts working me up a quote on a "Jasper axle". I thought "damn, 130C ~ 260 F, that is HOT. No wonder it is whining". I then asked, "130 C right"? (Most infrared devices will read either degrees C or degrees F). This guy, who is in his late 20's at most, says "no, degrees F". I looked at him incredulously, took his quote, and told him "I would think about it".

I didn't have the heart to point out to him that the human body runs about 97-98 F, and water does not boil until 212 F. 130 F is not HOT.

That is why I purchased my own $30 infrared temp sensor from Amazon. That 3d temp scanner he used costs about $500, but it is useless if you don't have a feel for temperature readings.
Reply With Quote
  #8  
Old June 25th, 2020, 11:31
old_man's Avatar
old_man old_man is offline
NAXJA Member
 
Join Date: May 2003
Location: Loveland, Colorado
Posts: 15,837
Re: whine and rumble in overdrive (38-45), disappears at 55-60 on highway

Pulling the rear driveshaft isolated the issue to the rear. If all is fine with the driveshaft joints (SYE?), then it is rear axle related. Whine is almost always gear related. Pull the diff cover and post up pix of the gears.

Ideally you would flush the oil off the gears with carb cleaner and then do a pattern check.

From my experience of 25 years of dealing with axles, I would list the following in order of probability.

1) poorly set up gears
2) bad pinion bearings/wrong pinion nut torque (too low or backing off)

I didn't see where you said what axle type....

3) bad wheel bearing
__________________
Tom Houston - Former Colorado Chapter President, current Treasurer , Terminal Adrenaline Junkie, and Rocket Scientist
Loveland, Colorado My teardrop build
You're just jealous because the voices don't talk to you.
Reply With Quote
  #9  
Old June 25th, 2020, 20:04
lawsoncl lawsoncl is offline
NAXJA Forum User
 
Join Date: Jan 2006
Location: North Idaho
Posts: 5,311
Re: whine and rumble in overdrive (38-45), disappears at 55-60 on highway

Quote:
Originally Posted by bpatto10 View Post
It looked bad, and then he said "the differential is overheating, it is reading 130 in the pinion area". He immediately starts working me up a quote on a "Jasper axle". I thought "damn, 130C ~ 260 F, that is HOT. No wonder it is whining". I then asked, "130 C right"? (Most infrared devices will read either degrees C or degrees F). This guy, who is in his late 20's at most, says "no, degrees F". I looked at him incredulously, took his quote, and told him "I would think about it".

130*F is perfectly normal if he drove it at speed. Even up to 190*F is normal if you've been hauling a trailer uphill at speed. The temperature is going to go up, simply because you're doing work to heavy gear oil. Sounds like they have a nice scam going, convincing people they have a bad rear axle.
Reply With Quote
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Death wobble disappears BCKNBLK OEM Tech Discussion 3 July 3rd, 2017 22:14
Help with rumble. mtbxj87 Modified Tech Discussion 1 January 16th, 2015 08:35
LOUD Rear Vibration or Hum disappears with rear Drive shaft removed Dustys Modified Tech Discussion 60 December 3rd, 2014 08:46
Front End Noise, disappears in right turns. Makapo OEM Tech Discussion 8 June 13th, 2014 13:20


All times are GMT -7. The time now is 09:21.


Powered by vBulletin® Version 3.8.9
Copyright ©2000 - 2020, vBulletin Solutions, Inc.
NAXJA and NAXJA logo's Copyright NAXJA. All content/images Copyright NAXJA 1999-2014