5th gear growling while climbing with load (6 speed transmission)

[klenger]

Towed the 5er for the first time on I70 in Colorado with the new truck. While climbing in 5th gear, I heard a growling sound on and off. It seems that it only happens in 5th gear, and only when loaded. The sound is pretty loud, and doesn't seem normal. Other times it sounds totally normal. Any ideas?



Other than the noise, the HO 6 speed with 4. 10's is fantastic. 65 MPH on flat highway in 6th is really nice.



Thanks for the expert help.



Ken

 

[Ram4Sam]

Built in noise?

Ken, I believe this has been tossed around before. I think it is the nature of the beast, so to speak. If I remember right, someone explained that 5th gear is on the mainshaft of the trans and doesn't use any other gears on the secondary shafts(5th is a direct or 1 to 1 ratio). The gears on the secondary shafts, when you are in 5th, aren't being used and have no load on them. I believe that the unused gears vibrate, oscillate, rattle a little,etc. due to their unloaded condition.



This makes sense to me so if anybody has a better explanation, chime in here. My truck also does this.



Sam

 

[rob10858]

it does seem to be the nature of the beast. both of our 2001. 5 duallys have the same strange howling sound when in a hard pull, but only in 5th. it comes and goes. not the fan clutch, not airbox related, [all of our guys have crawled around the cab trying to identify this , while someone else is driving of course] and no one has figured it out yet . had a transmission guy tell me once that "harmonics" in the gear wheels can make some very strange noises. well, we have 28000 and 30000 miles on these trucks, after 10 months, and have gotten use to the "ghost in the machine"

 

[DRR-24V]

My truck does the same thing when pulling hard in 5th gear.

 

[Big A]

Ken,

I dont know if you saw my post or not, but my 5spd makes a strange sound when pulling up a grade with a load in 4th. I realize they are 2 different trannys, but it makes me wonder if it has something to do with pulling hard with direct gear, like Sam said.

Big A

 

[mbrolin]

The 6spds make noise?What noise?Cant hear over the working Cummins. H/D trannys have a habit of making unusual noises. After all,they were built for working not quiet luxury.

 

[klenger]

Thanks for the input. I'll be going back home on Tuesday, over I70 eastbound. There's a 10 mile climb to Eisenhower Tunel that will be another test. I hope that you guys are correct and that the transmission's OK. I'll have the dealer check the transmission fluid level at the next (first) oil change. Other than the noise, the truck did great. I'm glad I traded the 5 speed.



Ken Lenger

 

[joesoot]

I got the growl today(empty), it only happened around 2300-2500RPM, could get it in 3rd, 4th, 5th, and 6th but only after it's hot... if I stop and cool the truck down, it didn't growl until after a few grades or right after cresting the grades... I know it's not the fan clutch... this growl sounds like gnarly bias tires coming thru my transmission hump

 

[JJW_ND]

I have heard this several times on the 2001 6sp I drive for work. It only makes it when it is good and hot and pulling hard. Higher the RPMs themore likely. I really wonder if it is not something in the drivetrain (trans or Tcase or Exhaust hanger) touching when everything is heated up and enough twist is applied from the engine under a load. I have looked and looked several times and can't seem to find any areas of concern.



I can make this truck produce the sound if a big enough hill is close in the area. Had no problems in WY and MT. Only a few small ones here in ND.



The sound is very noticable. On a hard Mountain pull it is very easy to mae the sound come and go. In this truck it did it in at least 4, 5 & 6.



jjw

ND

 

[klenger]

The noise you are describing is what I am hearing. I just ignored it and everything seems fine.



FYI, driving up the west approach to the Eisenhower Tunel yesterday towing ~10,000 lb 5er, I was able to stay between 50 and 55 MPH in 5th gear, and slowed to about 47 for about the last . 25 miles before the tunel. The truck has about 600 miles on it. I am pleased with the difference over the 5 speed 3. 54 I traded in. I plan to keep the engine stock, and I can live with this performance.



Thanks



ken

 

[klenger]

Topic continues at https://www.turbodieselregister.com/forums/showthread.php?s=&threadid=25608&perpage=15&pagenumber=1



See you there...



Ken