I have been experiencing new sounds as I am traveling along in high gear at 20 to 40 miles per hour. I was thinking clutch problems but took it to my mechanic today and he says differential. So next week it goes in and he will determine what parts are needed and I will get them.
4 speed non synchro transmission.
7-34 on diff tag (4.86?)
Any suggestions as to what else should be looked at?
I don't think anything has ever been touched on the diff.
When I depress the clutch or shift to neutral the noise stops.
The diff is also leaking around the middle

 

So you're coasting when you push in the clutch and or have shifted in to neutral ?

If thats true i would not think differential, but it won't do any harm to check it.

Do you hear the noise while accelerating or when under a load ? it could be something as simple as a U- joint or transmission issue. It shouldn't be to difficult to determine.

Let us know what you find, good luck.

 

Easiest thing to do is pull the drain plug on the diff and look for chunks of metal or larger than normal presence of metal.


I have had noises come and go with accelerating or coasting end up being a drive shaft issue. Seized U-joints can do it. Most people check for sloppy u-joints. A tight or seized bearing in the joint often gets missed and cause vibrations and noises.


You can put the truck up on stands and put it in gear. Have somebody listen and pin point the noise.

 

If the differential is leaking, make sure it has lubrication therein. How long since it was changed? Do check for metal shavings, filings, etc. Like suggested, universal joints would be a good place to look. The truck may be yelling at you for not bringing it to TS15.
Edit: I would suspect there are many differential sets floating around that have been removed.

 

Fortunately I was not able to make it to TS15, I don't think it would have made the 1600 mile round trip.......I have found a source for any part I may need and it is only an hour away.......I trust the guy to diagnose the problem correctly and honestly when I get it in to him, his shop is full and his lifts occupied......I replaced the 90wt oil with 140wt oil about 2 months ago, I checked it yesterday and topped it off, only needed a couple of ounces

 

Just went and got under the truck and see that the leak is where the drive shaft enters the differential.......when I grab the shaft and turn it turns about 1/2'' is that about right?
Ed
near Philadelphia

 

With the wheels blocked, trans in neutral, see if the pinion can be moved up-down-side-to-side. If it can, it means the pinion bearings have lost their pre-load.

 

If it is just rotating movement, not up and down or side to side as Ross mentioned, 1/2" is fine. Some of these Timken axles have a lot of gear slop. If they are maintained with plenty of oil, they are pretty much bullet proof. These 3/4 ton Timken axles have been used in sprint cars for years.
It could be a bad differential side bearing or a pinion bearing if it noisy under a load.

 

 

I'm more familiar with this form:

 

Well just got the truck back again and the noise seems to be gone now, here is what has been done
1) After putting the truck up on the lift mechanic felt the problem was not in the differential but in the drive shaft, primarily the carrier bearing. Took the shaft apart and cleaned everything and found that the only thing needed was the seals.
NOISE STILL THERE
2) Took it back in and pulled the clutch and transmission, found that the pilot bearing and throwout bearing were bad so replaced them along with the pressure plate, and clutch disc
All seems fine now, NOISE IS GONE. BUT oil pressure is now showing low on the gauge so I will start a new thread asking help on that
Ed