This is going to sound like such a newbie question but I've only changed differential fluid once before and that was 20 years ago on a Ford Ranger when I was a teenager so once I take the cap out of the differential, how do I know if I need to add any fluid?
Park on a level surface. Remove the cap or bolt on the diff cover. The fluid should be up to the bottom of the fill hole. Add fluid until it starts leaking out of the hole - that is the full mark. Then put the cap or bolt back in.
OK guys this is what I know so far regarding this noise/vibration. First of all I added a quart of 75W-90 Gear Oil to the front diff. When I pulled the plug on the rear diff, fluid poured out. It was black.
I don't see any dents or dings on either drivershaft. I also tried wiggling them around the U-joints and they didn't budge.
So I drove it on the Interstate and as usual as soon as I get to 65MPH the noise starts. It's like a roaring or rumble. When I go faster the noise increases. If I take my foot off the accelerator the noise is still there. If I turn the wheels, the noise is still there.
I don't know if this will help, but I used my cellphone and made a video of the noise. I've uploaded it to Youtube. You can listen here:
Someone said to remove one of the driveshafts? How complicated is that? I'm a basic mechanic that has replaced starters, alternators, water pumps, brake calipers, etc, etc but never done any type of major engine or transmission work.
How do I check the pinion yolk?
Also someone said try 4H. How fast can I drive in 4H? Keep in mind this noise doesn't start until over 65MPH.
I want to get this fixed!!!
Last edited by chris31419; 10-18-2013 at 05:57 PM..
4Hi is good for any speed. I drove for over a week once with my rear drive shaft in the shop (Just remember not to drive in 4hi on pavement after re-installing the drive shaft!).
And when working with u-joints, be careful that the caps don't come off and spill the needle bearings! You can use masking tape to hold them in place.
You might also want to mark how they were connected so they go back on the same way (something to do with phasing...)
Just listened to the video...
Are you referring to that metallic "buzzing" noise that comes and goes a couple of times??
Other than that I heard nothing odd. You should hear my tires roar on the highway
The quality of the sound of the video is poor. The sounds is a constant roaring noise and the sound increases the faster I go after 65MPH. So should I just try driving over 65MPH in 4 high or should I remove the front driveshaft to try and eliminate the noise? I thought I read that the driveshaft still spins in 4high? From everything I've read on this forum it sounds like this could be driveshaft related...
If you want to start with the front shaft out, then all you do is drive normally (in 2wd).
Driving with the rear shaft out, drive in 4hi up to what ever speed you need in order to determine if the problem is still there. Just don't do any jack rabbit starts
*From what I have read*, your transfer case *probably* won't leak fluid with the rear drive shaft out, but I'd feel better if someone chimed in and confirmed...
If driving with one or the other shaft out "fixes" the symptom, post the result.
So, if the noise came back after REINSTALLING the drive shaft and driving in 2hi, then it's either the output shaft of the T-case, the U-joints on the drive shaft, the balance of the shaft, or the pinion bearing (or some combination of them). Not sure if a problem with the ring and pinion would go away when not being turned by the engine...
I am not sure what the first thing to check would be, but the T-case output shaft and the pinion should be checked for excessive run-out and the drive shaft checked for worn U-joints and balance.
Hopefully others will chime in with other/better suggestions.
Yeah I hope others will chime in as well. I did NOT remove the driveshaft. All I did was drive it at 70 MPH in 4high and the noise went away. As soon as I shift back to 2 High at the same speed, the noise returns.
I crawled under it again today and noticed that I can push up and down on the front driveshaft and it wiggles just a tad. It does it on both ends of the front driveshaft. Is that normal?
I'm not sure if my front drive shaft needs to be rebalanced or if the U-joints need replacing or both. Any help would be appreciated.
Last edited by chris31419; 10-20-2013 at 01:13 PM..
It doesn't sound like the problem is in the rear differential.
The front diff holds 1.48 quarts, so if you added a whole quart, it has been running
very low for a while. Did you notice a lot of metal shaving stuck to the back of the
fill plug when you took it out? Did adding the gear oil seem to reduce the noise even
a little bit?
You should ask yourself where did the oil go? If you park the Jeep on a slant sideways,
does oil leak out the downhill end of the axle? If so you have a bad axle seal.
If the oil was low for quite a while, it may have caused extra wear to one of the pinion
See if this applies to your case: (From the Factory Service Manual, page 3-17)
The axle shaft, differential and pinion gear bearings
can all produce noise when worn or damaged.
Bearing noise can be either a whining, or a growling
Pinion gear bearings have a constant–pitch noise.
This noise changes only with vehicle speed. Pinion
bearing noise will be higher because it rotates at a
faster rate. Drive the vehicle and load the differential.
If bearing noise occurs, the rear pinion bearing
is the source of the noise. If the bearing noise is
heard during a coast, the front pinion bearing is the
Worn or damaged differential bearings usually produce
a low pitch noise. Differential bearing noise is
similar to pinion bearing noise. The pitch of differential
bearing noise is also constant and varies only
with vehicle speed.
When your 4Hi is engaged you are loading the diff, when it is disengaged, it is coasting.
Replacing pinion bearings should be done by a professional and that would cost a bit.
If you take it slower, you could get by maybe for years. I change my driving habits depending
whether I drive my jeep or my station wagon, which cruises nicely on the highway.
Your 4wd is "Part-Time" - you should not drive on dry pavement with the 4wd engaged.
The front and rear wheels are mechanically locked and on dry pavement there is no way for
them to slip. After a while, it would tear up your transfer case.
By the way, you can give the zerk on the front driveshaft slip yoke some grease. Are the
U-joints in your front drive shaft the greaseable kind? If so grease them and see if that helps.
On the front driveshaft, I'm told it is the single front u-joint that wears out the fastest. So
you might try replacing just that one as a cheap and easy fix if greasing doesn't help.
RLE, You are a fountain of knowledge. Now that has me worried about why the front diff was basically empty. I didn't see any metal shavings on the plug. It looked like dried grease on the inside of the front diff. I know that this Jeep sat for almost 3 years without being driven so maybe that contributed. Adding a quart didn't change the noise.
The transmission shop also added a quart to my transfer case. The PO recently had a front main seal replaced so there is oil everywhere under my rig that I need to get cleaned up.
I only drove for no more than a mile in 4High.
I called the driveshaft shop and they said it would cost $12 per U-joint and $20 in labor if I bring in the shaft. $44 total to replace both U-joints in the front shaft. It's another $80 if they remove the shaft so I plan on removing it myself this week and taking it to them. It's also $50 to re-balance it, when I asked how do I know if it needs balancing they said there is no way of knowing unless they put it on the machine.
Should I have it balanced or just try replacing the u-joints first to get rid of this vibration?
You can take off the front driveshaft yourself. At the front, you remove the four little bolts that
hold the two straps to the yoke. An 8mm wrench should do it. At the rear, there are four more
bolts that hold the double-cardan unit to the TC yoke. They are also 8mm, I think. Keep the
straps and all the bolts, but I would buy a new set of straps/bolts at Napa.
Then take a test drive and see if you still hear the noise. (Don't put it in 4Hi with the
If the shop is not used to working on Jeeps, you might find one that is if you want the
two u-joints in the CV assembly changed, too. Their labor rates don't seem bad. As for the parts, $12 per u-joint seems cheap. You might just go to Napa and get some good quality
u-joints (non-greaseable, since you are not using 4x4 offroad much) and a new set of
straps/bolts for the front of the shaft.
At this point you could still sell the Jeep and get something that would be better on the
highway. If you start working on it too much, you'll never want to sell it.
Last edited by RLE; 10-21-2013 at 12:27 PM..