Discovery 2a Sherlock Holmes---Find the Whine

[Pommie Ken]

Hi, I have a 2003 Discovery 2a V8 98K KM. It has a slight whine at the front.

I list the evidence and clues below and wonder if any experienced Expert/Detective can point me in the right direction?

1. The whine only appears once car warmed up and only on the overrun/off the accelerator. Slightest touch of power on and it disappears.
2. It is not loud and changes in pitch from a high concert E to about on octave below as the car slows from 60 Km/Hr down.
3. Recent rebuilt and balanced front and rear drive shafts from Hardy Spicer. Was there before this.
4. All auto transmission, front and rear diff/transfer case fluids changed, was there before and after.
5. If I shift auto in Neutral while happening on road whine still there.
6. If I shift auto in neutral while happening on road and transfer box in neutral it stops.
7. With transfer box in neutral and Auto box in drive it stops.
8. Stationary with Transfer box in neutral and auto box in drive and raise revs, no whine

Like I say it is not loud but keen to diagnose in case it gets any worse or causes failure.

Suspect front diff, T Case ???? So can anyone figure out whodunit??

Thanks
Ken

[Tombie]

Sounds like just a bit of gear whine in the TC.
May not be sinister, I can’t tell from here.

[greg-g]

Mine was the front drive shaft, one of the universal joint cups was getting hot to touch.
After a drive I'd have a feel of the temperature of everything in the drive line to see if anything feels abnormal.
I realize you've rebuilt the suspect components but it costs nothing to check.

[AK83]

'98 D1 auto D1 here, and not long after I got mine, I also had a very slight whine from under the car. The whine noise was heard whilst on the power, and could be made to disappear with feathering the throttle, and heard gain will full trailing throttle.
It was very slight and I just assumed it was the 'old LT230 whine noise' as I remember from my RRC converted from an LT95 to a LT77+LT230 setup years ago.

After a while in the D1 tho, the whine suddenly(as in on a drive) went bang, and the whine got a whole lot louder. The bang was the TC jumping into neutral while at 90k/h on the highway, and when I realised it jumped out of high range and back into high range, the original faint whine then turned out to be a full on screeching noise .. unbearable at about 80k/h. But again, the noise could be totally eliminated with a partial throttle, and a faint whine noise on full trailing throttle.

Eventually got a changeover TC fitted and no noise/zero whine from the rebuilt TC box at all since then. Now I have a baseline of how quiet my LT230 box is .. totally quiet, at least compared to he early LT230 I changed too in my RRC
Changeover place said the noise was that "a bearing had spun inside the TC". Didn't explain exactly which bearing, and I didn't ask(didn't care!) .. my only concern was that the rebuilt TC was working .. and working better .. which it was.

I'd say Tombie is on the money .. probably a gear or bearing or shim wearing/worn .. making the noise.

To eliminate the front diff, as you have a 2a, and assuming that you have a TC diff lock lever, you would remove the front drive shaft lock centre diff and go for a drive up to the point where you know the noise will occur.
I would have thought that if it were front diff, the noise would more likely be induced under power, rather than on a trailing throttle(all my noisy diffs on my previous cars had always made noise that way(Rodeo, Frontera, Falcon XF, and RRC).
That is, in opposition to how your noise is induced.

Hope that helps.

[discorevy]

^^^ Arthur............ Conan Doyle[bigwhistle]

[djam1]

Motul gear 300 almost eliminated mine
Expensive oil but very good

[Pommie Ken]

Elementary!

[Pommie Ken]

Dropped front drive shaft off as suggested, locked the diff and went for a run.......Moriarty was still with me.....so still the whine on the overrun. Guess that eliminates the front diff and points to the transfer case??????

Anyone in Perth who can diagnose/rebuild with the right components?

Rdgs
Ken

[Toxic_Avenger]

Do you have any passengers?

[discorevy]

Aztech ( dazza td5 on here ) , or Rovertech ( Kevin Falconbridge ) will be able to sort it, otherwise speak to Cameron at auto trans r us

[Pommie Ken]

Do you have any passengers?
I sense mischief afoot
'

[akula]

Oops misread the OP.