Loud engine knock- Ouch!!

[JB Mechanic]

Hello everyone, I am a tech and new y
to this forum but you guys all seem pretty cool you sound like a bunch with great attitudes and you're very helpful so.... here's my here's my dilemma.
I've got a customers 2003 turbo diesel .9 24v cummins, has a tuner, customer had his injectors rebuilt about a thousand miles ago and a valve adjustment done as well. He went into a store for about an hour came out of the store started up with a pounding lower and sounding knock shut it off, towed it home etc. I come to it it sounds to me like a wrist pin it's really loud solid right in the middle of the block it sounds like I cannot determine exact location though. I isolated injectors did not determine a single cylinder misfire help

 

[NIsaacs]

Take the fan belt off and run it. It might be the belt tensioner.

 

[cerberusiam]

When "injectors" and "rebuilt" are used in the same sentence that is by far the source of the problem. How did you isolate injectors? If it is injector knock capping the offending injector off will usually stop the knock, at least change it, unless it has already damaged that piston\rod assembly.

 

[DonFitzwater]

Who did the customer get his injectors rebuilt from? I’ve had terrible luck with the cheap shops. Chinese garbage is everywhere.

 

[Silver600]

I had a bad knock like you describe, my #5 injector tip cracked, sprayed fuel to the side of the cylinder and melted the piston. Didn’t deform past the rings so I never lost compression and never had blow by.