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General Category => Tech - Help Area => Engine-Driveline-Wheels-Tires => Topic started by: DieselHub on September 18, 2017, 01:34:28 AM

Title: NV4500 transmission noise
Post by: DieselHub on September 18, 2017, 01:34:28 AM
Looking to see if anyone has experienced gear rollover noise from an NV4500. I have 1995 C3500HD, NV4500, 6.5 diesel. I assume this is a single mass flywheel setup? Truck only has 60,000 miles on it. Transmission produces a relatively loud growling noise in 1st and 2nd gear at idle speed. Soon as you tap the accelerator ever so slightly, noise disappears (by 800 rpm its gone). Transmission shifts nicely, never ground a gear and never missed a shift. No complaints other than the sound. I have brushed it off as gear rollover noise because I have had some noisy SMF setups in the past. However, it's a lot louder and more pronounced than any of my other experiences (Ford and International trucks come to mind). Slight noise in neutral, not nearly as pronounced and not really a growl. Does not sound like a throwout bearing to me but I've only ever had one go out. I've searched high and low and have not found this to be common...any other experiences? Thanks in advance...
Title: Re: NV4500 transmission noise
Post by: ED-NY on September 18, 2017, 07:33:59 AM
DieselHub welcome - can't help with any NV4500 related noise but have experienced a similar condition with the early NV3500 units.  Input shaft bearing noise that was corrected by GM upgrade in later models. Had the condition on my S10 pickup with T5, pilot bearing wore out so bad (70,000 miles) that the clutch plate actually off centered and touched the pressure plate when pedal was pushed down.  Had to install a new bearing and shims on the input shaft.

I'm sure someone will jump in.

Title: Re: NV4500 transmission noise
Post by: RPF207 on September 18, 2017, 09:54:55 PM
Hey, welcome! I've got a '99 c3500HD with a nv4500. 50,000 miles on the truck, about 4,000 miles since the trans had a mainshaft swap to convert it to 4wd. All new bearings, all new small parts. There are two scenarios where I get noise from the trans. 1) when I'm coasting to a stop with trans in neutral (clutch in or out) I get what sounds like rollover. Another is when I've been using the truck for a while hauling or plowing and I let the clutch out in first and roll with no throttle, not an easy noise to explain but goes right away once I tap the throttle. Probably those good ol low rpm diesel harmonics coming through the single mass flywheel. Something else I've learned.... owners of vehicles with early GM nv4500s especially those behind a diesel filed many complaints about rattling noises in the trans. So mid '90s GM produced their own and very heavy harmonic balancer which gets severely pressed on behind 5th gear, helped a lot. I purchased and installed this balancer when I converted my trans to 4wd
Title: Re: NV4500 transmission noise
Post by: GM Guy on October 04, 2017, 03:23:45 AM
While I am not convinced its normal, I do have one growl-ey NV4500 in a 95 C2500 that has not given up yet. It has a noise in neutral as well.
Title: Re: NV4500 transmission noise
Post by: DieselHub on October 08, 2017, 01:08:21 PM
Thanks for the input. I am likely to sell the truck after the first of the year and this is definitely not a good selling point! But it shifts fine so I have just lived with it.