Getrag Noises - Ideas?

[LDechaine]

I was driving my truck the other day and I had been on the freeway for about two hours and when I came to a stop and was downshifting, I noticed some pretty bad bearing-like noises coming from the Getrag.



Now up untl this point it has shifted pretty good and has never really complained about anything. I don't lug it, and I have overfilled it (up to top PTO cover bolt) with Mobil 1 Extended-Life 5w30 synthetic for the last 25k miles or so that I've owned it. It only makes unusual noises when you are downshifting and are compression braking. If the clutch is in, it is silent. If you are driving normally (accelerating or cruising) it is quiet. The noise appears to only be in 3rd and 2nd gears.



My question is... what is the most likely cause for the noise? Would the transmission be worth rebuilding at this point or is it a lost cause? I had to get the truck home (approx 95 miles), but I drove it very carefully and did not compression brake (didn't cause it to make the noise) on the way home. when I got home I changed the oil in the transmission and it was clear and clean (I change it every 10k miles or so and it was due again). I also changed the oil in the transfer case and diffs too, as I felt it was a good idea.



Given the fact that there was not any metal shavings/pieces/anything out of the ordinary in the oil, I am hoping the transmission can be saved. I have only driven the truck once since the oil change, around the block as a "test" and the noise was still quiet prevelant.



Any ideas/suggestions would be greatly appreciated! Thanks!!



BTW... it's a '93 W250 with 130k miles, I have owned it since 105k or so.

 

[matches]

When the clutch pedal is in it is silent? Does it only make the noise when shifting and the clutch pedal is in? Or does the location of the clutch pedal not matter? The reason is could it be the pilot bushing making noise, I just replaced my clutch for that reason, stock clutch @193k miles, but I also babied it.

 

[dpuckett]

I was actually thinking throw out bearing- mine made noise for a while when idling in neutral with the clutch engaged (pedal up). Disengage the clutch, (pedal down) and it'd go away. Now it doesnt do it anytime.



If the oil was clean and clear, I wouldnt worry about it and just drive it. They do make some noise under load, and when compression braking, which may not be ideal, but I'd be concerned if a getrag was totally slient. You can take a styrofoam cup and put the bottom on the end of the shifter handle, and listen to what kind of noise you get there. it acts as a megaphone and amplifies any noises you wouldnt normally hear over the engine, radio, etc.



Daniel

 

[1stgen4evr]

Well, noise from the Getrag is never good. You can take the side covers off and see quite a bit. Check to see if there is end play in either of the shafts. Look for scuffing. Check the magnet.



Is the noise only with the clutch in. Could be a throw out bearing going south. Also, noise from the rear end can telegraph through the drive line and manifest at the transmission.



I have zero experience with compression brakeing.



The Getrag IS repairable if you don't run it to destruction.



James

 

[LDechaine]

To clarify... the noise is NOT there when the clutch is depressed/in. The noise is only there when the clutch is out and you are using the transmission to slow the truck down; ie compression braking. The noise (as near as I can tell) is only in 2nd and 3rd gears, and is definitely not there when in 4th gear. Thanks, and sorry for any confusion!

 

[dpuckett]

A little gear whine isnt unusual, esp in lower gears. May not be good, but not abnormal. Girlfriend makes fun of the little whine it makes when I am going too fast (15-18mph) and put it in 2nd.



-DP

 

[matches]

I agree with Daniel, my trans makes some noise, but I was wondering how do you hear that over the motor, the A/C on high and the stereo on? That seems to fix most strange noises on my truck!

 

[1stgen4evr]

"You can take a styrofoam cup and put the bottom on the end of the shifter handle, and listen to what kind of noise you get there. it acts as a megaphone and amplifies any noises you wouldnt normally hear over the engine, radio, etc. "



This is very efective. You can learn to differentiate most of the noises that the drive line makes as well as the injection pump. I use a hard plastic cup but most any fast food cup will get some result.



James



edit: added " ", from Daniels post

 

[matches]

Is your truck a Piano? Then why are you trying to tune it?

 

[ARhine]

I don't need a cup to hear the noises comming from my shifter.

 

[LDechaine]

Same here ARhine. If was a "little" noise I probably wouldn't be concerned. But since it's a noise that suddenly popped up, and I can quite clearly hear it over the XM Satellite Radio blasting, the wonderful clack of the Cummins and the exhaust coming out of the dual 5" smokestacks... I figure I have a problem.

 

[1stgen4evr]

I don't need a cup to hear the-- - - - -



... I figure I have a problem



You betcha. I am convinced that the engagment of the transfer case on the output shaft holds the main shaft while things grind themselve into oblivion with the 4x4. On the two wheel drive, when the bearings go slack on the main shaft, the transmission rebels and won't continue. But unmistakably, the 4x4 model will go past rebuild. If you like the NV 4500, I think you will soon be running one.



James