Drivetrain whine - FG434 + Entertaining Pics

gait

Explorer
something else to check - gearbox in neutral and transfer in 2wd and wheels on ground - take hold of rear drive shaft and try to rotate, both directions. There should be very little play. The more play/movement the louder the diff whine will be. If there's lots of play it can be felt sometimes when changing from decelerating to accelerating, an obvious "clunk". Can be worn ring and/or pinion, or poor pre-load.
 

jhrodd

Adventurer
I have an FG434 US spec turbo/w intercooler. It's very quiet at any speed. It has 318,000 miles on it (520,000 km) I'm the 2nd owner.
 

Aussie Iron

Explorer
No trouble running the oil that you put in as that would be normal for transfer case. That is the grade that I would also run in the diffs. We drive in hotter climates than a lot of other places in the world. On colder mornings (as in the desert / probably Victoria High Country) I just start driving slower to let everything warm up.

Dan.
 

dZak

New member
I'd be removing the rear shaft and handbrake drum and taking it for a drive in 4H on the front diff. That will eliminate the rear diff etc.
just take it easy and don't stab the throttle as the front shaft etc is not as solid as the rear.
It does however sound like a gearbox noise. Have your drained the oil and checked for metal lately?
Canter boxes have a problem with the pilot bearing on the front of the mainshaft wearing out, usually accompanied by snatching or grinding into 4th.
What year model is your truck?

Dave
 

Spoony

Member
I put 85-140 in the transfer and I think it's less prounced, haven't driven for hours straight yet though.
Going to out the same in the diffs.

I haven't drained the gearbox oil. It's always had a whine since I got it, drained fluids then near 1 year ago and all were very good. But yes makes sense to check the box. So it could be that whining, the gearbox shop probably given me a bum steer haha

Does the bearing sound like gear whine?

As for shifting it all shifts really well no grinding into gears or snatching.

It's 1990 Fg434 with about 340,000km.

Cheers.
 

asep

New member
I have the exact same problem on my 2006 nps300. 220,000kms. Exact same symptoms.
I even went to the cost of a full gearbox / transfer case rebuild, no change to the whine. Bugger.
I also tried dropping the whole driveline back from the transfer case to the back diff, so inc centre bearing. Driving around 4h, so front wheel drive only. No change in the noise.
Interestingly, while testing it on road if I get it up to speed then coast along in neutral, clutch in or out, if I apply a little bit of pressure to the gear stick like I am about to select a gear the noise seems to appear again, maybe not as loud but still there. It's doing my head in.
Thinking now it's a motor bearing noise under loaded conditions.
 

Aussie Iron

Explorer
I also tried dropping the whole driveline back from the transfer case to the back diff, so inc centre bearing. Driving around 4h, so front wheel drive only. No change in the noise.
Did you remove the axles so the rear diff is not turning, otherwise the rear diff is still circulating and can still be the problem.

Dan.
 

asep

New member
Did you remove the axles so the rear diff is not turning, otherwise the rear diff is still circulating and can still be the problem.

Dan.
Didn't do that, but the diff still turns when it coasts along in neutral with no noise so not the rear diff.
 

Spoony

Member
Asep, Interesting you've got the same thing going on. Sounds like it's doing your head in.

Did the rear Uni's tonight and also pulled the front shaft which needs a new slip joint.
While appart I spun it up to 90 in 5th and used the handbrake for load. The Whine could be heard so 100% not the diff.
Can only do this briefly for obvious reasons so picking if its box or transfer isn't really possible.
 

Spoony

Member
Oh, on another note how much does drivetrain oil type affect performance (and intern fuel)?

I ask as since going to 85w-140 hills that use to hold speed now loose speed. Only change is oil grade
 
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Aussie Iron

Explorer
Oh, on another note how much does drivetrain oil type affect performance (and intern fuel)?

I ask as since going to 85w-140 hills that use to hold speed now loose speed. Only change is oil grade
It would surprise me if it did. Warmer weather would make a bigger difference. Hotter air is less dense.
The difference between driving on a hot day and a cool evening.

Dan.
 

Spoony

Member
It's sapping 1 of my 3 horsepowers haha
Yes cold doesn't make it go faster like it did on many previous turbo cars. I put it down to engine air density vs fuel, ie air increases, fuel doesn't, on a diesel not gonna help power

I guess if i was rich could put a 90ish grade full synth in the transfer and rear diff. Would certainly reduce churning and pressure losses but should do fine holding up to temps.

The manual only states 140w in the front diff for 40+ climates. 2wd rear the same. FG lsd and transfer though is 90
 
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