whining while coasting..auto GV

[WaZook]

Hey folks, just a quick question..i recently whipped off the Bighorns because i was able to pick up a super cheap set of new alloys and new highway tyres and (probably due to the newfound silence of the ride!!) have noticed a slight "whine" when i take my foot off the accelerator at higher speeds (80kmhr+). The noise completely disappears when i accelerate again, or even just gently put my foot back on the gas.
Anybody know what this is?...am i dreaming up a problem?...hope i am!
cheers for any advice!
My GV is a 2009 V6, 5 speed auto
Mat

[Max]

I'd suspect the rear end, based on that scenario!

What's the gear oil level and when was it last changed?

[*Kiwi]

Since the noise appears on the unloaded side of the axle gearset (be it front or rear) I think it's not a wear issue. I would wonder if it had anything to do with resonances excited by the the CV joints, given the lift.

Obviously change the oil in both diffs if you're not sure of the condition but I don't think you have anything to worry about.

I'm amazed how small the (aluminum) diff housings are on this full time-4WD generation of the GV. Even the 2WD models seem to have the same small rear diff which has to handle the full load. My first-gen diesel had relatively massive iron diff housings front and rear.

My 2000 Xterra developed a axle gear whine at 15k miles due to Nissan leaving a small quantity of grinding compound in the oil. That noise appeared as a pure ~400 Hz tone at around 55 mph.

[WaZook]

cheers for the replys guys, regarding the oil being changed...as sad as it is im not sure. Its done 80000kms and has always had the factory logbook servicing @ the dealership where i purchased it. Its due for another service soon so ill get it checked out!

[DBO]

The diffs in the GV are a hypoid gear design, so due to the constant contact pressure they should be very quiet when properly lubricated and matched. As already suggested, get your diff oil changed first, but I somehow doubt that's your issue since you say that the whine is only under decel. Anyway, if you're still getting significant noise after the oil change, especially only under deceleration, it'll most likely mean that there's uneven contact between the drive pinion and the main gear.

The cause of that could be wear on the gear set itself, or a shift in the contact position due to wear on the pinion bearings. In any case, to get it diagnosed properly, it'll mean that the diff has to be removed, taken apart and then rebuilt. If you're lucky it could mean just a new set of bearings and everything re-adjusted - done. If the hypoid gear set is worn, then you're probably up for both pinion and bevel gear as they will come as a precisely matched pair from the factory.

[*Kiwi]

Originally Posted by WaZook

Its done 80000kms and has always had the factory logbook servicing @ the dealership...

According to the service schedule they should have changed the diff oils at 15,000 km.
I would not let that go too long. In my experience with a gen-1 GV and a Swift the magnet provided inside the drain plug is far too small to hold onto any significant load of metal particles. I can only assume the gen-2 GV has the same design and you can imagine what those particles will do to bearings.

[dkguffe]

I had a similar whining on mine, judging by your explanation.

Turned out that I had sucked in water in the front diff, and that bearings, pinion and crown wheel were rusted and bust.

$2000.00 repair..

[WaZook]

Originally Posted by dkguffe

I had a similar whining on mine, judging by your explanation.

Turned out that I had sucked in water in the front diff, and that bearings, pinion and crown wheel were rusted and bust.

$2000.00 repair..

ouch, hoping thats not the case here, ill take it in next week and get it checked out. Got the big Kimberley trip planned for mid year so i need to iron out any and all issues prior to that
Thanks guys

[Kathmanducas]

WaZook - I'm in Perth, with 2009 GV V6 also. Mine has had same hint of a whine since I picked it up (approx 75,000k's), but doesn't seem to have gotten any louder in the 10-15k's since then. Shall keep an eye on the feedback you get from dealer, as mine will be heading in for 90k service in about 2 weeks.

[Dugway 52]

I can only assume the gen-2 GV has the same design and you can imagine what those particles will do to bearings.

Our new GV (Gen II 4 cylinder) 2.4L auto (Canada) front, rear and transfer case oil was changed at 5900 KMS. The front and rear diff oil was absolutely filthy, and the magnets had a very large quantity of "fuzz" attached (I always inspect these on all our trucks personally); the transfer case oil looked virgin (absolutely new).

Based on the manufacturer's schedule of 1st change at 15,000 KMS: IMO, this is far and away too long an interval (given the full-time nature of the Zuke's all wheel drive). My front and rear diff change interval will always and henceforth be at 6000 KMS (at the same time as my full synthetic oil change).

The cost of the dealer diff change is incredibly inexpensive (the price of a meal for 2 out) considering the hellacious down-side to a premature differential re-build. Cheap insurance.

Good luck,
Dugway-