Medium to high pitch growl from the rear end

[vstrom]

For the past month there's been a sound coming the back end, getting a bit louder as time wore on. It's a growl/ whine that appears from about 50kph and higher with power applied. If I apply the clutch at those speeds the sound disappears.. it also disappears when I let off the throttle and coast. You can only hear it when gas is being applied but not necessarily only under acceleration.

I think I've narrowed it down to the rear diff. I checked the rear oil and found it milky. Somehow I got water in there (eventhough I had all the drivetrain oils changed 18 months ago.. I may have been ripped off), so I dropped the oil. Lo and behold the magnet on the plug had a ball of grey sludge with it. Guess the gears have been chewing themselves up for awhile. So, new oil in, it runs slightly quieter for a couple of days but now its back and maybe slightly worse. I was going to change the oil again in a week or two just to check for any more shavings, but now I'm wondering just how long the rear diff will last? Time to find a new one?

Also wondering if I should/could disconnect the rear driveshaft and drive around in FWD (4WD) for a couple of minutes just to make sure that it really IS the rear diff?

I also greased all the U-joints and that didn't seem to do too much, and all the oils in the drive train looked good.

Never played around with the differentials before so looking for abit of wisdom or if anyone else has had the same noise.

Thanks

[thelazygreenfox]

Vstrom
Try adding a differential treatment from Lordco or(?). If that doesn't quiet the diff change the fluid back to 80/90 again. Plan on changing the treatment every time it gets noisy.

The sludge on the magnet is normal, it's the filings that are bad.....

If you pull your driveshaft you may lose trans fluid.

You could ask a local tire shop to put your deli up on their hoist and drive it. They'll help narrow down the noise. Say you think it's tire noise. I did that.

It's about $1500 to rebuild a diff. Ball park figure, may cheaper but still too much cash. Look for a low mileage diff off a wrecked L300. There's lots around.

Monitor the temp of your diff with a laser thermometer. They're great tools. The diff may run noisy forever before it need be changed.

PM me if you need to.
TLGF

[vstrom]

Thanks LazyFox. I'll go to CanadianTire and Napa and see what kind of treatments they might have... never even thought about an additive.

I'll be snooping around for a used diff.. I understand that Mitsubishi and Dodge shared a bunch of parts back then.. is there anyway to cross reference Dodge/Mitsu parts?

[thelazygreenfox]

Vst
It's a long shot on the cross referencing of a major item like that. If the chryler part starts with a MR or a MB it's from Mitsu.

Look up your diff part number on Amayama trading, then do a google search, maybe it'll cross reference for you. That's worked for me quite a few times.

Marty may have a diff for you. He keeps his prices low.
TLGF

[Lapprentis]

Ok, my Van caught that Disease too: Low Frequency Loud Noise from the back at about 80Kph and more...Sometimes when iddling at full stop, a different noise too...Have an LSD and yes, proper additive in it.

Less likely a fluid level-quality or grease issue.

Went under the Van and CANNOT move the Drive Shaft with my hands (can move front one easily for about 30 degrees rotation).

Any Clues ?

Lapprentis