whining noise from G/box or T/case?

[tineapedis]

Hi Guys

I own a late 1994 Disco 1, 300 TDI with the RT380 Transmission and I'm trying to diagnose a noise that has developed over the last 4 weeks.

I added a 2" lift which gave me vibration from the front propshaft which within 3 weeks of adding the lift one of the UJs starting to break. I replaced the front prop with a wide mouth heavy duty unit which reduced the vibration but not completely eliminated it, I also corrected the castor & drove around for three months with the heavy duty unit until I stumbled across the idea of a cardan unit which I have now in place.

Unfortunately I now have a whining noise which is audible in 3/4/5 gears and is slowly getting louder, I don't have any vibration or shudder, just the whining, its only present when I accelerate, when I take my foot off the gas it goes away.

I'm assuming it's the bearing or the shaft where the front prop joins the T/case, only because this was the area of the previous vibration.

Any thoughts or ideas would be very much appreciated.

if it is this shaft or the bearing how easy would this be to change?

thanks in advance

Wayne

[justinc]

Wayne,

Very possibly a differential whine, possibly front if it sounds like it is at your feet area. Get someone to drive and sit in the back and see if it is louder, to check the rear differential. The reason I am mentioning diffs is due to the 3/4/5/ gear road speed increase. It could also be the transfer case intermediate shaft bearings, best way is to get the vehicle up on 4 axle stands, select difflock and drive it up to about 60 or 70 km/h and get under and have a listen. MAKE SURE YOU USE HEAVY DUTY AXLE STANDS ON LEVEL GROUND!!!

JC

[Blknight.aus]

going against what JC has said, does changing the power application while maintaining road speed do anything? (as in is it there when youre coasting or only under power?)


do this before you mess about with stands and running it up on the stands. you might also luck up and be able to figure it out by jacking it up and feeling for motion on the outputs that shouldnt be there.

IF you want to bring it out my way Im happy to make my mechanics stethescope with the magnetic heads available for you and road testing can be done in safety.

[tineapedis]

Hi guys

When I'm coasting at 90kph for example, with my foot off the accelerator there is absolutely no noise but when I touch the accelerator the whining returns.

When I'm accelerating through the gears the noise is present and increases with the revs

many thanks

Wayne

[justinc]

I don't seem to be making much sense lately, as Dave points out, with coasting or powering on when the noise changes this usually denotes a crownwheel to pinion angle change due to worn or loose pinion bearings. With your front shaft vibe issue recently I'd take a guess the front pinion brg is loose/ worn.

And yes, sitting the vehicle on stands is very much a last resort, but done safely is a good way of quickly pinpointing issues in a drivetrain.

JC

[harry]

dave, tell me more about the magnetic sthesocope,
trying to find a noise myself, afer replacement of the disco's donut with a solid tail shaft,
it now whines like hell, where the donut was probably hiding the noises from the rear diff.

[tineapedis]

Hi Justinc

I'm assuming your indicating that the bearing that may be worn is the one in the T/case which attaches to the front propshaft?

If so is this easy to replace?

Hi Blacknight, I'd love a 2nd opinion, would you be free one day next weekend?

many thanks

Wayne

[justinc]

Hi Justinc

I'm assuming your indicating that the bearing that may be worn is the one in the T/case which attaches to the front propshaft?

If so is this easy to replace?

Hi Blacknight, I'd love a 2nd opinion, would you be free one day next weekend?

many thanks

Wayne

Wayne, no I meant the front differential pinion bearing, where the shaft goes into the diff itself. It is possible to have a noise from front output bearing in transfer case, but usually this isn't sensitive to power on/ off scenarios like a diff pinion brg.

JC