Rear diff howels only when HOT????

[roperteacher]

I have an appt to have my Rear diff fixed once and for all next tues, but made a very interesting observation these last few days... . In the morning when it is cool, the Rear end howl pretty much disappears... . in the afternoon when it gets 80 degrees +, it howls like the dickens!!! I did just receive my AMSOIL 75-90, which I believe claims to lower Rear diff temps by 20 degrees. . I wonder if this might fix the howl? Or should I let the dealer figure it out... THanks!

 

[klenger]

Let the dealer look at it first. Even if the Amsoil eliminates the noise, it will be only masking a real problem.

 

[roperteacher]

THat is what I was thinking... . let the dealer look in case they damaged something by putting in the wrong lube when they rebuilt it... or the rear end just might be one of those 15% that needs replacing due to bad construction at the factory. THe AMSOIL won't spoil! LOLOL I'll keep it until I need to change the rear diff fluid again at 15,000.

 

[GDouglas]

Mine is the same way. I have the whine from 65 to70. When cool, I can barely hear the noise, but tow a load for about 10 to 20 miles and you can really hear it mainly at 66 to 67 mph with just enough throttle to maintain steady speed. Outside of this 2 to 3 mph window and it is pretty much quiet. Coasting through or accellerating aggressively through the "window" generates no noise at all.



I did do a gear pattern check back when I changed the rear lube out and I had a textbook perfect pattern on the pull side and satisfactory on the coast side. Oddly enough, my noise occurs only during a slight pull which is where one would think there would be a problem with the pull side of the pattern.



Yeah, it does suck for a $40k truck to have a little something out of the normal like this but the way I see it is if my axle had soft gears or very poor contact patterns from the very beginning, then the noise would have been getting more worse as the mileage accumulates to the point where something tore up. The truck has 7/70 powertrain coverage and I will keep an ear on the noise to see if it gets worse. If it makes it through 70k miles and the noise is still the same level, I will have enough trust in it not to leave me on the roadside. Other than that, I will keep the radio playing at it's usual level and that will maintain my sanity.



Until then, drive it like you stole it while under warranty. This way you will know if everything proves itself out or not.

 

[Vic]

Wrong Oil Used

Originally posted by roperteacher

THat is what I was thinking... . let the dealer look in case they damaged something by putting in the wrong lube when they rebuilt it...

A fellow in our camping club has an AA axle on a 2500, had an oil seal replaced and gear oil replaced with synthetic 75W-90, he thought. Turned out that garage used 80W-90 petroleum stuff. Atter running some 400 miles towing his RV he had hubs running hot. Checked oil. It was way too thick compared to Amsoil 75W-90. Discovered oil was 80W-90. Running Amsoil now but still finds hubs are running hot, but maybe less so. ... . Anyone had similar experiences?

 

[roperteacher]

I had my dealer install the 75-90 that AA Axles calls for. Don't have the Part # in front of me... . I don't get out and feel the hubs to see if they are really running hot or not.