Slight knock

[71IDI4x4]

After runnin this truck for a few hundred miles now I can hear a slight knock in it. Not sure where its comin from sounds like it could be a very light rod knock. Dont sound like a lifter goin,and Ive bled the injection lines as best I could in a hurry ie couldnt get to number two on DS cause of air box. It did get run out of fuel this past weekend either the gauge is off or it was angled just enough not to suck what was in there. Didnt bleed the fuel system after that but didnt sound any differnt so I figured it was ok. It also has a few exhaust leaks and the pyro sending unit is wedged against the firewall pretty tight. What are yalls thoughts of what it could be, injector?

 

[hesutton]

Certainly could be an injector. The old trick of indiviually cracking each injector line with the engine idleing to see which injector makes the noise go away doesn't always work. But, it's worth trying. How old are the injectors?

The exhaust leaks could be a source for that noise as well. Exhaust leaks can make some weird noises that can scare the crap out of you.

If the thermocouple on the pyro is hitting the firewall, it could be making some weird noise as the engine moves with RPM changes.


Heath

 

[DavidBlaine]

I had a slight header leak once that caused the same noise. I'm glad I checked before getting pissed off and tearing the engine down. Check the exhaust very carefully and the injector wire pull is a good starting place too.

David

 

[71IDI4x4]

I have no idea how old the injectors are on the thing I was told the motor had 150,000 but who knows whats been replaced and what hasnt. I did get it back from the exhaust shop today after gettin 4 inch put on and that seemed to help the cab noise and sounds like they fixed the exhaust leaks but can still hear a light knock/ rattle even after its warmed up all the way.

 

[RLDSL]

A slobbering or stuck injector in a diesel will sound exactly like a gasser about to throw a rod, while one of these things will rarely ever throw an actual rod

 

[71IDI4x4]

Alright thanks guys I really appreciate all the help ill try bleedin the air out of em this weekend the right way and hopefully that will shut it up some. Ive heard what a gelled up injector sounds like in a dt466 in one of the trucks at my work and it wasnt like that theres no skip in the motor like that truck had. What about rocker arms?

 

[hesutton]

I'd climb under the hood with it idleing and try and zero in on the location/source of the noise. It could be lots of things. If it appears to be coming from under one of the valve covers, by all means, pull the cover and have a look.

Do the injectors have old grey paint on them? If so, they may be the originals and due for replacment.

Heath