Clicking/scraping noise when accelerating *You'll be stumped*

So, here's a tricky one. I have a 99 Silverado 1500 5.3 with 170k miles. Just today I noticed a clicking scraping noise as i accelerate. The faster I accelerate the worse and louder the sound gets. The scraping is a repeating noise much like something falling into a fan blade but I do not see any obstructions. The sound will occur even when the truck is not moving but only if parked uphill on an incline. If i'm parked facing downhill, there is no noise. Otherwise, the truck works perfectly fine and doesn't seem to be lacking in any power.

Ruled out: Driveshaft - sound occurs when drive shaft is not in motion. Brakes - sound occurs when truck is parked.

So, here's a tricky one. I have a 99 Silverado 1500 5.3 with 170k miles. Just today I noticed a clicking scraping noise as i accelerate. The faster I accelerate the worse and louder the sound gets. The scraping is a repeating noise much like something falling into a fan blade but I do not see any obstructions. The sound will occur even when the truck is not moving but only if parked uphill on an incline. If i'm parked facing downhill, there is no noise. Otherwise, the truck works perfectly fine and doesn't seem to be lacking in any power.

Ruled out: Driveshaft - sound occurs when drive shaft is not in motion. Brakes - sound occurs when truck is parked.


check the engine fan/ motor mounts for failure ..

remove the flywheel cover could have picked up a rock etc...

Pull serpentine belt for a test and see if sound goes away.
Check your engine/transmission mounts real close.

Is noise coming from front or rear of engine or center or rear of truck?

Pull serpentine belt for a test and see if sound goes away.
Check your engine/transmission mounts real close.

Is noise coming from front or rear of engine or center or rear of truck?

The sounds is coming from the middle front part of the truck, nearly the center of the engine.

One other piece of information that is probably useful: The metal scraping sound does not start immediately after the truck is started. If I start the truck, the scraping sound will occur 2-4 seconds after the truck has been started.

Did you pull belt and see if noise quits?

So, here's a tricky one. I have a 99 Silverado 1500 5.3 with 170k miles. Just today I noticed a clicking scraping noise as i accelerate. The faster I accelerate the worse and louder the sound gets. The scraping is a repeating noise much like something falling into a fan blade but I do not see any obstructions. The sound will occur even when the truck is not moving but only if parked uphill on an incline. If i'm parked facing downhill, there is no noise. Otherwise, the truck works perfectly fine and doesn't seem to be lacking in any power.

Ruled out: Driveshaft - sound occurs when drive shaft is not in motion. Brakes - sound occurs when truck is parked.

I had a 93 did the same thing. fly wheel cracked..

I had a 93 did the same thing. fly wheel cracked..

Ok, after a bit more research, I think your prognosis is right on. Somethin is up with the flywheel. It's cracked or something is scraping it. I can turn a wrench but i'm no mechanical genius. I can do all my own brakes and I'd replaced a fuel pump or two. Is this something I could fix or would it be worth while to take it in to the shop?

Ok, after a bit more research, I think your prognosis is right on. Somethin is up with the flywheel. It's cracked or something is scraping it. I can turn a wrench but i'm no mechanical genius. I can do all my own brakes and I'd replaced a fuel pump or two. Is this something I could fix or would it be worth while to take it in to the shop?

thats what your problem is, the fly wheel is paper thin. auto zone had it. cant rember how much but real cheap price. as for replacement me and my son did it in no time. pull the trans, the hardest thing is lifting the tranny back up. try and rent a trans jack, unless you have help.its not that hard you can do it and save some cash. and while you have te tranny out change fluid and filter.. ken

Ok, after a bit more research, I think your prognosis is right on. Somethin is up with the flywheel. It's cracked or something is scraping it. I can turn a wrench but i'm no mechanical genius. I can do all my own brakes and I'd replaced a fuel pump or two. Is this something I could fix or would it be worth while to take it in to the shop?

first like I said take the flywheel cover off ,,see if you picked up a rock etc...then mark flywheel and rotate to inspect...

also this engine a 5.3L was not produced in 1993..I doubt the flywheels are the same ...

Thanks for the troubleshooting help. I was pretty much stumped for the longest time and ended up taking it to a shop expecting the worst. Turns out I had a ring gear out of place in my starter. The mechanic rebuilt and reinstalled my starter and that was it. Still waiting on the bill but can't be as bad as a transmission or flywheel problem. Thanks for the help!

Thanks for the troubleshooting help. I was pretty much stumped for the longest time and ended up taking it to a shop expecting the worst. Turns out I had a ring gear out of place in my starter. The mechanic rebuilt and reinstalled my starter and that was it. Still waiting on the bill but can't be as bad as a transmission or flywheel problem. Thanks for the help!

since you are not making repairs having this mechanic charge you for repairing an old starter would be not wise ...

when the internal parts/bushings gears wear its time for a warrantee starter replacement ...you might get a couple of years or a couple of weeks out of it .