Rear End Howl or Whine.

[pharmer]

Got a 1983 GMC, half-ton, 4-wheel, pick-up that I use as a "farm truck" and only drive it 500 miles or so a yr. Just noticed a small whine from the rear end that goes away when you let off on the gas and resumes when you reapply the gas. Is there any particular rear end lube or additive that will quieten this whine and how long does it take for a rear end howl to develope into a major "can't drive it" situation?

 

[3 Mad Ponchos]

Can't answer the longevity issue, but for maintenance why not just start with a diff fluid change & see if that helps any.

Cheers, 3MP

 

[pharmer]

3MP, I had exactly the same idea that you suggested.I drained the old differential fluid and it was a little bit milky. I had some Schaeffer's #267, 80-90w. on hand and put in about 5 pts. of good, fresh lube. It may have quietened the whine a little but noise still there. It might have helped more if I had gone with a heavier weight such as 85-140w. but I didn't have any in my supply.

 

[Mike_dup1]

quote:

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how long does it take for a rear end howl to develop into a major "can't drive it" situation?

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The best answer is, it all depends. At 500 miles a year, maybe never (most likely), maybe tomorrow (I would doubt it)?

quote:

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Is there any particular rear end lube or additive that will quieten this whine

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I would change the fluid and see. But I would not expect it to solve the problem. I had a 1964 Impala for about 15 yrs till last year. The rear end had a whine like you describe. Many years back when it was bugging me I had a differential expert check it out. He drove and told me its the pinion gear that is wearing from use. Very often you can stop the whine by adjusting the pre-load on the pinion. He said, it won't hurt anything and has probably been like this since new. So I let it good for many years. Once spring when taking the car out of storage I notice the pinion seal was leaking. Having ignored the whine for some 10 yrs I had not though of this when I had a the GM dealer fix the seal. As I was driving home, I happened to notice there was no more gear whine. It was just normal wear and tear all along.

 

[ALJAMES]

pharmer,

The noise you have described is typical of a loose pinion shaft or bad pinion bearings. I would advise having it looked at as it may be just the pinion nut being loose. However, make sure someone competant is doing the work. If the nut is overtightened, then the pinion bearings can be easily destroyed.