While plowing snow last night I was up against a hill with the window rolled down. From a slow start I could hear a very loud KNOCK similar to a rod knock. I've never heard that before. As soon I get going it is gone. Also cannot hear it with the window up or just revving it. Maybe it is all the snow packed up under the truck? I did put some fuel additive in the other day...PowerService, think that caused it? I let the Diesel tech at work listen to it and he says it sounds SWEET and tight to him. ****.. to be concerned or not?

 

THey will give a pretty good sound, similar to a knock when under a heavy load at idle or when just applying a small amount of power.

 

Be concerned if the knock doesn't go away when you rev it up. Different fuel quality can make them more noisy off idle.

 

My 03 did the same thing, when letting out clutch in 2nd gear, engine would make a LOUD "clack, clack, clack" noise then go away at about 1000 rpms or so. I stopped buying fuel from the local "mart" at started buying from truck stop down the road. Pay 15 cents more per gallon , but NO MORE CLACK, and MPG went from 18 to about 21-22. Also I use FleetGaurd FleetTech fuel conditioner every 4 th tank. Recommended by Rocky Mountain Cummins.

 

THANKS, I will try fuel from another station.