How to diagnose / pinpoint "sticky or bad injector"

[MuddWeiser]

Still trying to "tune up" my CUCV on the cheap.

The truck has started to shake a lot at idle and sounds like someone is shaking a "jar of marbles" instead of the smooth sound of diesel knock...

I am thinking it might be the injectors, or likely a few "sticky/bad" injectors, so I am wondering how I might diagnose individual injectors so I can grab a set from a junkyard and replace on a "as needed" basis?

I am wondering if I can simply disconnect 1 at a time while engine running, listen for change in performance, and pinpoint bad injectors this way????

Any help or tricks would be appreciated.

 

[lavarok]

Timing?

 

[rnd-motorsports]

I like the Infrared Thermometer to find bad injectors look at each exhaust port and look for cool cylinders!

 

[dilvoy]

So you want to do the old pull the spark plug wire and if the engine dosne't run any worse, that one is probably good trick, but with a diesel. It may work, but don't get shot with any high pressure fuel. I bought a CUCV that had a horrible ticking. I thought that it had to be a bad injector for shure. I could hear it more from the interior of the vehicle than from above or below the engine. It turned out to be a swollen glow plug that somone loosened and coulden't get out and left it loose. That was an easy fix and the only thing wrong with the whole vehicle. Maybe you have something silly like that.

 

[JAsher45]

i have used three different methods to find bad injectors. IR temp prob on the exhaust to look for a cool cylinder. a stethoscope you can listen in on the injectors see which one is not like the others. you can also crack the line loose.. it only takes 1/4 turn loose for the pressure to bleed off. if the engine changes tone, tighten and move to the next, continue til you fin one that the tone does not change.. bingo

did this just start? does it do it after the truck is warmed up? could just be a bad glow plug while on the cold idle setting.... meaning the fuel is not burning until the cylinder temp comes up on its own with out the glow plug to heat the air

 

[Shop Rat Fab]

Check the harmonic balancer, torque convertor bolts/nuts, drop the alternator and power steering pump belts to eliminate the accessories as a possibility.

 

[grayw0lf]

Good info! I'll have to check out my injectors.