Chevy and GMC Duramax Diesel Forum banner
  • Hey Everyone! Vote for the Site Favourite ROTM winner for the year of 2021 HERE!
1 - 5 of 5 Posts

·
Registered
Joined
·
5 Posts
Discussion Starter · #1 ·
First timer here! Recently picked up an 07.5 Lmm with 295,000kms on her. Took the kids on a 5,000km trip towing a 4500lb trailer and ever since I’ve been getting a knock on startup and accelerating until it slips into 4th gear or so. I borrowed a laptop from our heavy duty dept at the college to check the balance rates and everything was in +-3. I did an injector cutout test and the knock was still present. I was hoping that it would target one injector! Any help or ideas here would be great before I take it to my local diesel shop? TIA
 

·
Registered
Joined
·
4,690 Posts
Is the knocking sound related to engine speed, or road speed?
 

·
Registered
Joined
·
4,690 Posts
I suppose it would be engine speed
Initially I was thinking that rules out anything beyond the transmission, and likely the transmission also. But it perplexes me about no knock in 4th gear or higher. If it were my truck, I would remove the serpentine belt and see if the noise stops. Look for any wobbling of any of the pulleys and crank damper. If no change, pretty much has to be the engine.

Any work done on the engine recently? Regular oil changes? Fuel filters also? If nothing of note at this point, diesel shop might be your best choice. That assumes you have a good one.
 
1 - 5 of 5 Posts
Top