HELP Y'ALL HAVENT LET ME DOWN YET!! I have a 04.5 3500 5.9 ctd...306k miles,developed a knock in top of motor.thought it was injector making noise ..still starts an runs .slight power loss..slightly more smoke..unplug #1-2 inj plug an it goes away. unplug 1 inj at a time an its there.. moved inj around tryn to isolate prob to 1 cyl..switched #1 to#3...an #2 to#4..now i have just #1 cyl makin knocking sound..when inj is disconnected [#1] noise stops.. all others sound normal..could it b electronic problem..only code originally was like low rail pressure....pump and #4,5,6 inj were replaced at 170k... luv this truck please help!

 

Anybody??????

 

OK, you said "Anybody" so I'll give you something to look at, but a CTD expert I'm not.

Seems to me, the knock only occurs when an injector is working at #1 Cyl. Disable the injector, the knock goes away. Move a different injector in it's place, the knock comes back. Not an injector problem, IMHO.

With the slight loss of power, and increase in smoke, I'm thinking you have a valve that dropped far enough to not be able to close properly, but not far enough to beat your piston to death yet. I think, since that valve isn't closing 100%, what you are hearing is the detonation of the fuel in #1 cyl. Disconnect the injector, no fuel to detonate, no knock.

Makes a bit of sense to me, but again, not an expert. Hopefully someone will chime in. If not, maybe you should do a compression test (Leak down test?). Good Luck.