Differential noise. How hard to fix?

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06-06-2018, 10:47 PM

Scottwid

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Join Date: May 2018

Posts: 10

Differential noise. How hard to fix?

I’m hearing noise from the rear differential and from what I’ve researched it looks like it may be the pinion bearing. A hum/whine that starts around 40mph. Goes away if i let off gas but immediately returns if i press the accelerator again. 1995 montero sr. Is this a common issue? Have any of you done this repair? Could if be something else?

06-07-2018, 03:12 AM

fikse

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Join Date: Mar 2017

Posts: 11

All diffs will make a whining noise when they're worn. Wear is usually caused by bad/old oil and/or excessive abuse. Oil change might help quite some. I can recommend to use Royal Purple Max gear (75W-90 on yours?), top notch oil fortified with antifriction additives. I have used this in several diffs/gears with whining noise, and it helps alot. Not 100% always, but significant at least.

06-07-2018, 09:09 AM

Scottwid

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Join Date: May 2018

Posts: 10

I just changed out the oil and it did seem to help a bit. It makes me a little nervous because my grandpa had a diff lock up on the highway once. I don’t think mine is close to failing at this point. At least I hope not.

06-07-2018, 10:34 AM

fikse

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Join Date: Mar 2017

Posts: 11

If you got a slight improvement with an ordinary oil, you will have more improvement with Royal Purple, for sure.
An alternative can be high quality additives or prefferable some metal treatments. Qmi has some PTFE metal treatments that makes a tiny layer of teflone on metal surfaces.

06-07-2018, 11:24 AM

Scottwid

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Join Date: May 2018

Posts: 10

Good to know, thanks for the tip. I’ll look into getting a better oil in there. I’m going to lift the rearend up and see if i can focus exactly where the noise is coming from.