Great reply, thank you! I only knew (marginally from what I've read) about the one in the transfer case.

Currently I am using mine as a Mall Crawler (as Christian/Vera would say) so maybe no need to upgrade then.

Thank you again, you gave me pointers on lots of new things to learn/read

Cheers

 

Don't Coast !

 

No, one thing will not rule out anything different. You are down there anyway, you need to inspect everything. You have a noise of unknown origin, finding one source of noise does not mean that you don't have two or three or four sources of noise. You are needing to check diffs, driveshafts, axle bearings, carrier bearings, xfer case output shafts and bearings, all that stuff. You have no reason to assume that any of those things are good. What everyone has said about this likely being caused by the diffs is correct, but that doesn't mean that nothing else is bad.

 

Yep, thanks for the heads up. I am trying to understand which area to attack first.

 

That is not a wheel bearing/ hub noise, that would be constant. And as mentioned previously, check all fluid levels or have them changed. Make sure to inspect drain plugs for foreign materials/metal shavings. Every Dll l've owned had very little transfercase fluid. For some reason, maybe location of fill plug, is why it gets over looked.

 

Thanks for the input - that is what I think. I have changed all fluids (differentials + transfer case) as soon as I got the car (the mechanic not myself) and as per his analysis, everything was ok.

 

I diagnosed a similar issue earlier in the year. My reserach indicated drivetrain whine when coasting is probable the diff or t/case.

Changed to a heavier weight axle oil on the differential. Then checked if the drivetrain whine (when coasting abated).... no change. Engaged CDL, removed front driveshaft... test drove... still the same drivetrain whine underneath. Removed the rear driveshaft... still the same. I deducted the transfer case was the issue. Just recently replaced the t/case a couple of months ago and all good now. I have not have a chance to tear apart the old transfer case to determine the exact cause yet.

 

Thanks for the reply - really hoping it is not the transfer case, those are hard to come by where I live.

One question: removing the rear or front drive shaft would still let the differentials operate. How would you deduce they are not the problem?

 

It will still work as long as your Disco has CDL, and you engage it (it becomes a 2 wheel drive vehicle). Without CDL it won’t work.

 

Well, we have an interesting development:

I took it for a drive again to try to do more tests - drive in first gear only, second, third, try low/high, diff-lock engaged, etc.

And then I tried pulling the hand-brake while going down hill (not really sure if this is bad or not for the car). As I started pulling the hand brake the noise diminished. Eventually, as I kept pulling, the noise almost disappeared (almost because I am not sure, a lot other noises from the street/road could not let me be more precise).

Does this mean the problem is / around the hand brake drum? Or is it restricted to the transfer case?

Or it does not mean anything, differential in the rear could still be affected?

Thanks