Manual Trans Questions - noise at idle w foot off clutch

[Scooby]

I have an early build 06 with 78000 miles and when I am sitting idle at a light with trans in neutral and my foot off the clutch, I hear a loud constant whirring noise. When I depress the clutch pedal, the noise goes away... ... . what is going on... . and what should I be expecting to happen soon? (I am totally stock and tow a 5th wheel camper on occassion)



I don't have any high hp plans, so what would be a good (better than stock) clutch option for me?

 

[GCroyle]

1. Release bearing is turning 100% of the time, does not have freeplay by design. Period.

2. Pilot bearing is active with engine running, release clutch (pedal down) select gear, remain stationary. Engine is turning, input shaft is not, pilot is active.

3. Engine running, release clutch, select gear, remain stationary transmission is no longer turning. This eliminates transmission generated noises, but not pilot or release brg noises.



Might want to try an up close listen and see if you can pick up any direction to the noise.



The only way to take the release bearing out of the picture would be to remove the slave cylinder mechanically (leave it hooked up to the hyd line) pull the fork to the rear and secure with a tie wrap the fork back against the stud. This physically pulls the bearing to the rear and it stops rotating. Start the engine by overriding the saftey start switch. DO NOT PUSH THE CLUTCH PEDAL WITH THE SLAVE CYL REMOVED.



Now the only noise that you could hear would be transmission noises.



USE CAUTION WITH THIS DIAGNOSTIC TECHNIQUE YOU CAN CAUSE DAMAGE TO THE HYDRAULIC SYSTEM IF YOU PUSH ON THE PEDAL WITH THE SLV CYL REMOVED.

 

[Grizzly]

You have the Dual Mass Flywheel on your 06. The original clutches on trucks with the DMF are known to last only 75K miles on some. Others may get much more mileage. There's a recent thread about the G56 transmission with the DMF. Do a search.



george

 

[Scooby]

Thanks for the replies. I am aware of the 75K life expectancy which is why I am nervous! I don't think I have the skillset to run that diagnostic technique.

I guess I'm wondering what to expect if this noise I'm hearing is the clutch getting ready to leave me stranded.

Since the noise goes away under scenario 2 above, does that mean there is a problem with the input shaft? I've never replaced a clutch so I'm almost embarrassed to ask if that input shaft is something that is typically replaced with a new clutch or not?!



Thanks again!

 

[GAmes]

I do not have a DMF and sometimes get noise while idling in neutral. If I disengage the clutch the noise goes away. I can also quickly depress the pedal an inch or two, then release it and the noise will go away. It has done this since the conversion, roughly 52k miles ago. The trans had (according to the seller) 57k on it when I bought it. He gave me the DMF and the original clutch and PP. I couldn't give them away.

 

[Joseph Donnelly]

When the dual mass flywheel goes bad, you generally get shaking (heavy vibration) at idle in neutral. Your noise could be the input shaft bearing or “pocket bearing” inside the gear that the mainshaft fits into. The pilot bearing or clutch release bearing could be at fault, also.

 

[Scooby]

Thank you for the reply Joe. (I used to live in Albequerque when I was in K - 2nd grade..... learning to spell your town name when you are 6 years old living there takes on a whole new meaning!)



Anyway, when doing a clutch replacement, are these items usually replaced? I have never attempted to replace a clutch and don't have the time (or patience, quiet frankly with a 2 and a 5 year old) to undertake the project myself... . so I don't want to get taken for a ride by the shop when I have it done.



Thanks!

 

[Bob4x4]

The pilot and throw out bearing are changed out with a clutch job. The trans input shaft and or bearings are not. The 6 spd trans are best not opened up by the diy guys and most clutch shops