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[powerslinky]

hi guys ,  3.2 MV6 auto.  driving this new car home the other night , I noticed there is a whine which starts at 60  get to 75 & it's gone .

When it's  whining  between these speeds, as soon as you take your foot off the gas it stops completely. gas on again it starts

It is no more prominant when cornering either way.

Obvious culprits are   diff . . . wheel bearing  . . . or even exhaust drone at certain revs ( although twin pipes are out clear of the rear bumper)

Have not had chance to check as yet but would low diff oil be a possible cause 

Just looking for suggestions from anyone who had a similar fault           but this only occurs between 60 & 75
TIA   Al

[Magwheels]

The diff would be the major suspect in my book. Diff noise usually determined by loading and unload with the throttle and will normally disappear after a certain speed.

Not hard to change. It's just that you have to be sure the one you are changing it with is a good one.

I had one go on mine and it gets really annoying as it was right on the motorway cruising speed.

[powerslinky]

The diff would be the major suspect in my book. Diff noise usually determined by loading and unload with the throttle and will normally disappear after a certain speed.

Not hard to change. It's just that you have to be sure the one you are changing it with is a good one.

I had one go on mine and it gets really annoying as it was right on the motorway cruising speed.

Thanks Magwheels  . . because that is exactly what is happening here . . .  so diff is now prime suspect

[Entwood]

When my whine existed - at around 25 - 40 mph .. it was, eventually, tracked down by the following procedure ..

Measure the distance from the top of the wheel arch to the top of the rear tyre

Jack rear of car and place VERY securely on axle stands both sides.

Jack each wheel by a bottle jack under the lower shock absorber mount until the wheel is in its "normal" position by the measurement obtained in step 1 - This ensures the drive shafts etc are in the correct alignment to prevent damage and strange noises

Run the engine and select drive .... I was surprised that the autobox span up to just under 30 mph and 4th gear without touching the throttle .. but it did and the whine was instantly present on mine.

Under the car and pull on the handbrake cables one at a time to stop an individual wheel, as the whine did not stop this discounted the wheel bearings as the source ... and confirmed the diff as the problem.

Replace diff

Given the high speed of your whine you may need to modify the procedure a tad and have additional help .. to get the diff to the higher speeds ...   

[chrisgixer]

If it is the dif, this is a good opportunity to fit a 4.22 dif from a 2.6. If you wanted a bit more oomph.


Although it might be worth checking the oil level as the guide as well before condemning.

[powerslinky]

When my whine existed - at around 25 - 40 mph .. it was, eventually, tracked down by the following procedure ..

Measure the distance from the top of the wheel arch to the top of the rear tyre

Jack rear of car and place VERY securely on axle stands both sides.

Jack each wheel by a bottle jack under the lower shock absorber mount until the wheel is in its "normal" position by the measurement obtained in step 1 - This ensures the drive shafts etc are in the correct alignment to prevent damage and strange noises

Run the engine and select drive .... I was surprised that the autobox span up to just under 30 mph and 4th gear without touching the throttle .. but it did and the whine was instantly present on mine.

Under the car and pull on the handbrake cables one at a time to stop an individual wheel, as the whine did not stop this discounted the wheel bearings as the source ... and confirmed the diff as the problem.

Replace diff

Given the high speed of your whine you may need to modify the procedure a tad and have additional help .. to get the diff to the higher speeds ...   

OK thanks Mr. Entwood . .  will have a go at this . . at the weekend I would think when assistance will be available

[powerslinky]

If it is the dif, this is a good opportunity to fit a 4.22 dif from a 2.6. If you wanted a bit more oomph.


Although it might be worth checking the oil level as the guide as well before condemning.

What would be the negatives of going for a 2.6 diff then Chris?  Is it just a diff swap ? 

What about speedo readings & more importantly  fuel economy ? 

[Kevin Wood]

First thing I would do is top up the diff oil. They often start weeping at the input pinion oil seal, so could be it's just got a little low.

[Nick W]

I hadn't realised how noisy my diff was until I 'topped it up' with a litre of oil! A new pinion seal is on my to-do list.

[chrisgixer]

If it is the dif, this is a good opportunity to fit a 4.22 dif from a 2.6. If you wanted a bit more oomph.


Although it might be worth checking the oil level as the guide as well before condemning.

What would be the negatives of going for a 2.6 diff then Chris?  Is it just a diff swap ? 

What about speedo readings & more importantly  fuel economy ? 

Can't really answer the negatives, as I'm on different size wheels that will fuddle the situation. You will get slightly better acceleration though. But slightly higher rpm at a constant speed. About 3-400 rpm higher iirc.

Economy, not sure. I didn't have the 4.22 on there long enough, as it was swapped for an LSD 3.9 that's on there now. Not sure if its makes much odds, as you spend proportionately less time pressing the old pedal.


Its worth checking the oil level before doing anything though.

[powerslinky]

If it is the dif, this is a good opportunity to fit a 4.22 dif from a 2.6. If you wanted a bit more oomph.


Although it might be worth checking the oil level as the guide as well before condemning.

What would be the negatives of going for a 2.6 diff then Chris?  Is it just a diff swap ? 

What about speedo readings & more importantly  fuel economy ? 

Can't really answer the negatives, as I'm on different size wheels that will fuddle the situation. You will get slightly better acceleration though. But slightly higher rpm at a constant speed. About 3-400 rpm higher iirc.

Economy, not sure. I didn't have the 4.22 on there long enough, as it was swapped for an LSD 3.9 that's on there now. Not sure if its makes much odds, as you spend proportionately less time pressing the old pedal.


Its worth checking the oil level before doing anything though.

OK  . .will do the oil check  the same time that I do Mr. Entwoods  advised axle stand /jack up test , this weekend