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How to find a bad injector?

ShawnR

ShawnR

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Central, Ohio, USA
I am having an uncomfortable amount of white smoke even after fully warmed up. I was towing another truck today and was able to see it in the daylight against the black of the trailer.

It had been starting a little hard and smoking more on startup than it should. All glows and wires have been replaced and re-tested.

My injectors have lees than 20K miles on them, but they were recently transferred from my old 6.5 block to a replacement block. Maybe they got dirt in the nozzle or something?

How do you track down what might be the problem nozzle?
 
Crack each individual injector line at the injector one at a time. If the engine stumbles you found the bad cyl. It may be an injector, valves or rings.

Leo
 
It is a fresh remanfactured engine so valves and rings should be good. I'm not losing any coolant or oil, so an bad injector is about the only option left.

I am looking at plans to build a pop tester on google at the moment.
 
NVW said:
Crack each individual injector line at the injector one at a time. If the engine stumbles you found the bad cyl. It may be an injector, valves or rings.

Leo
Click to expand...

Every injector he will crack will cause the engine to stumble. Not sure if you can diagnose this problem this way.

Does the smoke smell like raw diesel?

IS it the same white smoke that happens on a cold start? (how much of that do you get?)

Have you checked coolant levels?

Check oil for cross contamination, fuel smell?
 
When I was chasing a bad injector (mine would knock under load sometimes), I had to buy a new one, and swap it one by one until It went away. Start on the easeist ones, and keep you fingers crossed its not Turbo side baCk.
 
ShawnR said:
I am having an uncomfortable amount of white smoke even after fully warmed up. I was towing another truck today and was able to see it in the daylight against the black of the trailer.

It had been starting a little hard and smoking more on startup than it should. All glows and wires have been replaced and re-tested.

My injectors have lees than 20K miles on them, but they were recently transferred from my old 6.5 block to a replacement block. Maybe they got dirt in the nozzle or something?

How do you track down what might be the problem nozzle?
Click to expand...
A bad injector almost always gives a knocking noise. a inj with a bad spray patern (a stream) should give white smoke only at low RPMs.

If they are knocking,like NVW said ,crack the lines one by one,till the noise stops.Thats the bad one.
The engine will always stumble if you take one cyl out.You cant go by that.

How old is the IP?
 
X2 on the IP. If not that, then yea, I would go with swapping a good injector out one by one until you find it.

I know it was asked already, but what does the smoke smell like?
 
Can you see the smoke AT ALL when truck is idling? If so swapping injector 1 by 1 you would know instantly which one it is.

Sometimes the knock only happens randomly and under load so I couldn't hear the knock when idling, so I coulnd't hear it go away by cracking an injector line.

You havn't even mentioned a knock, so I don't think you have one (it sounds bad, like cold advance valve flap all of a suddon on 1 cylinder) That's my experience.

Keep in mind, 4 of them are extremely easy to do.
 
Something else to try, When your engine is cold let it run for about 5 minutes or so, then hop up there and physically grab each injector by hand, see if one of them is considerably warmer than the others.

When I found my bad injector, it was the 3rd one I tried, and when I put my hand around it to start pulling the inj return lines I instantly noticed it was warmer then the others, felt warm/hot vs cold. So much so it stood out.

I want to think I could even feel the heat difference on the metal injector lines too.
 
I recently bought one of those little laser / infared thermometers. I will try that to see if there is a difference.

I have noticed a little white smoke at idle, but I haven't smelled it yet. It is never really bad, but it is there and it bothers me.
 
I carefully looked at (& smelled) the exhaust today at idle and couldn't smell anything at all (diesel or oil) and there was no smoke to be seen.

Coolant level was normal & oil was just a little lower than I remember, but still in the acceptable range on the dipstick. What color is the smoke of you are burning oil? when I was towing, the boost was up around 9-10 PSI. Maybe it is oil comming through the CDR only when under boost?

Injector pump and injectors both have less than 20K miles on them.
 
ak diesel driver said:
could be your rings aren't fully seated yet.
Click to expand...

I think I agree. A fresh gasser would be at around 500-1000 miles before I would feel confident the rings were seated. Driving unloaded for this time period with varying throttle is a healthy way to seat them in, as far as I know. I'm not sure what the break-in is on a diesel, though. Running natural oil instead of synthetic (not sure what you're running) for a whole 3000 miles or so may be the ticket, instead of the 500-1000 I mentioned above.

If it's still doing it at the 3000 mile mark, I'd look into it further if it was me. You seem to have covered all your bases.
 
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