NV3500/10 bolt gear whine.

[shelbyt.67]

NV3500/NP241/10 bolt gear whine.

Hey all. Got a problem here. Gotta a 5 speed NV3500/NP241 w/a 10bolt 3.42 diffy. Couple a three days ago a loud gear whine stared. My first thought was bad tranny or diffy. Diffy seals are leakin so thats this weekends agenda. I refilled the diffy with gear oil. Still the whine. The tranny fluid is new GM synchromesh and shiftin and motivatin fine. Also at the same time, the speedo is no longer accurate. Its reading 10-20 mph lower than normal. The whine is constant, loud from about 30-45mph under load, then quiets down some above 50. I'll be tearin into the diffy to see whats what but, the speedo has me concerned that its tranny related. VSS?

Any thoughts, experience???

 

[LT1/TA]

Have you checked the transfer case fluid level?

 

[shelbyt.67]

I have not!

 

[shelbyt.67]

Transfer case fluid is full and clean. Removed diffy cover. Found the outer edges of the ring gear worn down. Was unable to remove the axles to replace bearing/seals. The damn lock screw for the pinion shaft has busted off inside the shaft.
Still not sure why speedo is off tho.

Ideas?

 

[low4x4]

with the outer edges worn ...sound like the whine is from pinion and gear wear

 

[shelbyt.67]

with the outer edges worn ...sound like the whine is from pinion and gear wear

Like a bad pinion shaft bearing? Didn't notice any wobble or play in that location. There was back and forth play in the ring gear. I'm not sure how much is normal.

 

[LT1/TA]

I would check the pinion yoke and see if there is any play,as for the cross pin bolt I have used a punch to break the rest of the bolt.
Is there any reason why the whine started?

 

[shelbyt.67]

I would check the pinion yoke and see if there is any play,as for the cross pin bolt I have used a punch to break the rest of the bolt.
Is there any reason why the whine started?

There is no play in the yoke. The bolt is broken into the shaft. The only way I can see to loosen the shaft is to cut into the case to free the pinion shaft.

The whine just started out of nowhere. I am wondering about the speedo problem. why would the speedo stop working at the same time?
The transfercase fluid appears to be good?

 

[LT1/TA]

There is no play in the yoke. The bolt is broken into the shaft. The only way I can see to loosen the shaft is to cut into the case to free the pinion shaft.

The whine just started out of nowhere. I am wondering about the speedo problem. why would the speedo stop working at the same time?
The transfercase fluid appears to be good?

The cross pin bolt can be drilled and extracted by using a screw extractor,but unless you are very good at drilling and extracting I would just use a hammer and a big punch to drive the cross pin through the differential case and the you can remove the rest of the bolt hopefully with a pick/awl if not you will be able to remove the diff case and remove the bolt a lot easier on a bench than under the truck.The cross pin bolt threads are only in the differential case not in the pin so if you can break the bolt, the cross pin and diff case should be ok and all you will need to replace is the cross pin bolt vs the diff case.

The speedometer problem and whine starting at the same time makes me wonder about the transfer case,I know the transfer case has an oil pump in it.I don't know what the symptoms are when a pump goes out,maybe you can remove the speed sensor from the transfer case and inspect the case and sensor.

 

[shelbyt.67]

OK, Thx man. I think I'll try and repair the diffy again next weekend. The transcase will have to wait tho. If the oil pump is out then its gonna take more time than I got at the moment. preciate the help.