Engine/Transmission (1994 - 1998) Noise in third gear

[NScott]

I have a 98' 3500 with a NV4500. It shifts OK except going into third ( sometimes it chirps a little grind)and when it is in third gear it has a whine or growl that is noticeable both pulling and holding back. It doesn't offer to jump out of any gear. What are some of the best ideas of what it can be?????

 

[dieselburner]

Don't know for sure. I tore up my transmission a couple months ago when I was merging onto the highway and looked up and saw a herd of 18 wheelers coming at me. I reached down and flipped my "valet" switch which gave me full fueling. Unfortunately I had the pedal down at about 3/4 throttle and I snapped my main shaft right behind third gear. You gotta love the torque though.





:--) :--) :--)

 

[Strick-9]

You may have broken a tooth on either 3rd gear or the countershaft.



I've had a few nv4500's come in the shop lately with randomly broken teeth.



Not sure if that helps much, but without hearing or driving it, that's my guess.



-Chris

 

[Six_Man_Diesel]

Try to shift it really fast, use the clutch, if it grinds, probably the synchronizer. I do agree with Chris however, a tooth is a possibility. If it is a broken tooth, I think it would be because it was not manufactured correctly, gears should never break if lubricated properly. You can rule out bearings, as it only has the problem in 3rd gear, no noise in all other gears.



Hope this helps,

Willie

 

[1sand0s]

My fresh trans has the little "click" when cold going into 3rd if not patiently shifted. Up shift or downshift.

That should be the synchro. I dunno what noise you mean, but is it at all RPM ranges?

Mine sings like hell if you sauce it too soon, but on the way down it is basically silent. Dunno if this helps...

 

[NScott]

This thing has a muffled roar or sing only in 3rd gear. It sounds normal in all other gears. It tries to grind if not shifted very slowly when going into 3rd , no other gear tries to make any noise either going in, pulling ,coasting or holding back. Only 3rd.

 

[dieselburner]

When I broke my transmission, the main shaft was fractured right behind 3rd gear. The shaft was still together but only barely and the transmission was real hard to shift. Since the main shaft was bent, the shifter was hopping all over the place. I bought all new parts from Standard trans including a fully splined main shaft and rebuildt it myself. By the way, with 140K miles on the transmission, most of the fibers were worn away on my synchros. my transmission shifts perfect now. I am guessing that you have a problem with the speed bearing that rides under 3rd gear but you won't know for sure until you pull it apart.



Steve

 

[dieselburner]

When I broke my transmission, the main shaft was fractured right behind 3rd gear. The shaft was still together but only barely and the transmission was real hard to shift. Since the main shaft was bent, the shifter was hopping all over the place. I bought all new parts from Standard trans including a fully splined main shaft. By the way, with 140K miles on the transmission, most of the fibers were worn away on my synchros. my transmission shifts perfect now. I am guessing that you have a problem with the speed bearing that rides under 3rd gear but you won't know for sure until you pull it apart.



Steve