# Friends truck "grinding" when accelerating fast...



## mkwl (Jan 21, 2005)

I was riding in a friend of mine's truck from school today (uncle was borrowing my truck). He has a 2004 Chevy 2500HD 6.0L auto trans. When we were pulling out of thte lot up a steep"ish" hill, his truck accelerated fine, but made a sort of "grinding" you could feel when he first accelerated- I have no idea what it was, just wondering though- he had no idea either, said it had been doing it for about two or so months. I'm guessing it was something trans related, not sure though, because it didn't seem to always do it- just sometimes  Anyone have any idea what it could be?


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## streetsurfin' (Jan 22, 2004)

The fan hitting the shroud because of a broken motor mount?


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## flashinglight (Nov 19, 2007)

My buddies GMC 2500HD 2003 6.0 truck made a griding vibration when he turned sharp, turned out to be the rear end, had 90,000 miles, he changed the rear end fluid and it hasn't done it since.


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## mkwl (Jan 21, 2005)

You can like feel the vibration slightly in the floorboards- I'm guessing it's not a slipping trans then?


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## B&B (Nov 4, 2006)

Does it _only_ do it in a turn or will it make the noise when accelerating in a straight line also?


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## Earthscapes (Feb 2, 2001)

On my 04' I had a straight line grind/rattle noise. Drove me and dealer nuts for 3 months. Wouldn't do it all the time, but when it did you thought the thing was gunna explode. It ended up being the inside of the muffler came apart. They ended up replacing the whole exhaust system, under warranty at the time.


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## streetsurfin' (Jan 22, 2004)

Did he check the trans fluid? A low fluid level could cause a shudder in the trans, I think.


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## mkwl (Jan 21, 2005)

B&B;440099 said:


> Does it _only_ do it in a turn or will it make the noise when accelerating in a straight line also?


Seems like it's only when making a turn, then accelerating up a hill at the same time or soon after turning- not totally sure though, only did it in a turn when I as with him.


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## streetsurfin' (Jan 22, 2004)

Are these stock tires or oversized? It could even be something as simple as an oversized tire rubbing on a mudflap at full lock. Turning and uphill would indicate compression of one side of the suspension at near full lock. Have him go through full left to right steer qhile parked, and you be outside of the truck looking at clearances. Account for compression of the suspension and see if anything is close to rubbing.


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## B&B (Nov 4, 2006)

mkwl;440129 said:


> Seems like it's only when making a turn, then accelerating up a hill at the same time or soon after turning- not totally sure though, only did it in a turn when I as with him.


If it only does it in a turn I'd bet it has a GovLoc (locking differential) in it then, right?

If so, then it's not uncommon for them to do that when the fluid in the rear end breaks down. The clutches in the Gov Loc's will stick and chatter if the fluid is either low or broken down.


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