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Low speed whine

Mudslug88

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It’s at that k/m’s that things need to be replaced, general maintenance items.
Hanger bearing, meaning the centre bearing on the tail shaft,
possible, if it was replaced with a s/hand one.

it could be a number of thing,
From Front hubs, Power Steering Pump, to pulley bearings, transmission noises, centre bearing, diff bearing/gears due to no/lack of oil, wheel bearings, or the fuel pump, HVAC fan, or door seals causing the noise.

There are a number of thing it could be, but it’s a case of elimination without throwing parts at it first.
From what I was told it has a good service history. Going to start with the hanger bearing then will start the fun process of elimination!
 

UTE042_NZ

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My first guess is differential, because...
1. Wagon - easiest vehicle for diff noise to be heard in and it can echo around to the point where you can't tell where it's coming from.
2. Whining hum - yep that's the sound diff gears make when they or the bearings are worn.
3. Happens most at low speed when cold - diff warms up, the oil warms up, plus the gaps reduce and oil gets in the gaps.
4. And when coasting - ooh diff backlash!
5. 260,000kms - gears wear and so do shafts and bearings. Drain the diff oil, run a magnet through the oil you drain out of it and see what it picks up.

If the oil is clean the seller may have already done the recommended and replaced the diff oil with a slightly heavier grade and a additve. If it is grey and/or sludgy I would put any cheap normal diff oil in and drive it for at least 30 minutes to 1 hour at highway speed to warm it and drain again then put in a good diff oil suitable for that model and its high mileage, perhaps with an additive.

ASSUMING you have a non-LSD V6:
I think GM recommend an 80W-90 mineral oil be used for your model

I would warn against jumping straight up to higher viscosity 80W-140 synthetic oils for Limited Slip Differentials if your wagon doesn't have one.
 

Mudslug88

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My first guess is differential, because...
1. Wagon - easiest vehicle for diff noise to be heard in and it can echo around to the point where you can't tell where it's coming from.
2. Whining hum - yep that's the sound diff gears make when they or the bearings are worn.
3. Happens most at low speed when cold - diff warms up, the oil warms up, plus the gaps reduce and oil gets in the gaps.
4. And when coasting - ooh diff backlash!
5. 260,000kms - gears wear and so do shafts and bearings. Drain the diff oil, run a magnet through the oil you drain out of it and see what it picks up.

If the oil is clean the seller may have already done the recommended and replaced the diff oil with a slightly heavier grade and a additve. If it is grey and/or sludgy I would put any cheap normal diff oil in and drive it for at least 30 minutes to 1 hour at highway speed to warm it and drain again then put in a good diff oil suitable for that model and its high mileage, perhaps with an additive.

ASSUMING you have a non-LSD V6:
I think GM recommend an 80W-90 mineral oil be used for your model

I would warn against jumping straight up to higher viscosity 80W-140 synthetic oils for Limited Slip Differentials if your wagon doesn't have one.

Hey mate. Makes sense. Plenty of backlash and doing bearings is a no brainer. Planning to take a closer look this weekend.
New hanger bearing is not newish condition either. If the gears are in good nick I was looking at getting an open diff to swap in while the lsd is getting a birthday. Cheers mate!
 

Mudslug88

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Update! Problem fixed. Removed the drive shaft and straight away could see the 3 bolt flange on either side of shafts were not sitting level on the ground. Realigned spline and the whine is no more! Thanks for the ideas on the noise. Cheers
 
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