My son's 2003 3500 5.9 had a knock in it. After checking this forum, I decided it was injector knock. At cold start up there was no knock. After a few minutes it would start. The truck did not loose any power and ran fine. There was a lot of black smoke, with no signs of fuel in the exhaust. I pulled the wires off each injector one at a time, and when I did #5 the knock stopped. When I went to pull the injector I found one of the hold down bolts was loose. Should I try torqeing it back down 1st, or go ahead and pull it for inspection?

 

Did you loosen one, then go to the other to loosen it and find it loose or did you check that both were tight before loosening either? If you loosen one up, the other one will be loose. To install:

Install fuel injector hold down clamp and hold
down bolts. Alternately tighten clamp bolts to 10 N·m
(89 in. lbs.) torque.

 

Yes! He loosened one side then found the other side loose.

 

^^^ That is normal. The hold down is a "rocker" style. When you loosen one side the other will be loose too. When tightening up again, ensure you do it evenly alternating between the two bolts as described above.

Also, the electric leads on the top of the injector solenoid take very little torque. DO NOT OVERTIGHTEN... or you will be cursing over the cost of a new injector.

 

Replaced #5 injector and truck runs fine.