I was Traveling up the freeway at about 74 MPH and my engine started knocking. I've got a 1998 Dodge 2500 4X4 24v Cummins with a 5 speed.
I was towed home and had it diagnosed as being an injector I had all 6 injectors replaced the knock is still there, its not a rotating knock so I'm confident its not a rod. The more I run the engine the more I think its a lifter problem the engine is pretty loud but it runs smooth with no power loss. If any one has any idea please get back to me on this issue.

Thanks in advance

M. Gomez

p.s. the knock seems to be in the back towards number six cylinder

 

Probably melted #6 piston.

 

Wannadiesel

After having the injectors replaced I was told to drive the truck that i had air in the fuel lines so I drove my truck about 250 miles and the knock is still there no loss of power and runs very smooth other than the knock. It sounds like a loose rocker arm. i had the valves adjusted and they weren't off by much I'm lost

 

Sounds like maybe an injector pump on its way out.

 

you're probably right.

 

You guys telling me that a melted piston would not cause any power loss only knock. Without actually hearing the truck, you may have detonation, due to timing, or lack of fuel due to plugged fuel filter or poor fuel. Would be my guess.

 

All the Cummins engines are well known for cracking pistons above the wristpin boss, and for burning the crown down just low enough to cause the top ring to snap on each firing stroke. And, yes it will happen and there will be no noticable power loss until the cylinder is scored or the piston breaks through the top ring. Under each of the last two scenerios the engine is trashed at that point and the fix is very expensive. Catch it early enough and it is a relatively inexpensive piston replacement.

 

I was hoping it wasn't anything like that. I want take the time to thank all you guys for the Information. Thanks Again

 

If the piston is cracked there should be some reduced compression, shouldn't there be? Best way to tell for sure is to pull the head?