Defender 90 Vibration At 1600rpm

Hi all a few weekends ago I noticed a very loud humming/vibration at 1100rpm and 1600rpm I can hold the revs and the noise will continue but as soon as I go over or below in revs it will disappear. The noise sounds as though it's coming from the rear but who knows.

So far I've taken the rear prop off and the noise is still there.
Checked gearbox and t box oils. All good.
Checked the rear diff oils. All good.
Taken exhaust off and applied exhaust paste.

Is there anything else I should be looking at?

Cheers Reece

Check the front prop/UJ's

Front prop UJs, front prop balancing, tyre balancing?

As above, starts with vibration then a scratchy tiny sound, then the prop falls off

wireman said:

Front prop UJs, front prop balancing, tyre balancing?

Click to expand...

I completely forgot to mention I'm going to check front prop tomorrow, what is front prop balancing?? I've never heard of this??

All (most) props are balanced, you should see a small patch (thin sheet of metal the size of a big stamp) welded to the main part of the shaft. Also if the prop has been apart it might not have been reassembled in the correct place. Props should be either in phase or out of phase, (how the two UJs align) I can't remember which one Land Rover Defender front prop is.

I think there pre-balanced, just make sure it goes on the same way as it comes off.

wireman said:

All (most) props are balanced, you should see a small patch (thin sheet of metal the size of a big stamp) welded to the main part of the shaft. Also if the prop has been apart it might not have been reassembled in the correct place. Props should be either in phase or out of phase, (how the two UJs align) I can't remember which one Land Rover Defender front prop is.

Click to expand...

out of phase about 45 degrees,rears are in line ie in phase,its because front diff flange and front t/box flanges arent parallel

Thanks for all the input gents I'll have a gander tomorrow at the front prop

Bit of a weird one. I've had the front prop off but the sound is still there??? Also I took the whole exhaust off except the turbo down pipe and I can still hear the vibration. I'm confuzzled