how do you know if an injector is bad??

[Cummins Cowboy]

I read posts all the time about guys having trouble with injectors, how do you know if one goes bad??

 

[sag2]

By the melted piston? Sorry, just couldn't resist.

 

[TCDiesel]

Flow test,kill test,Post & Pre-Test,Oil sample,Oil rising,Smoke at idle,No start poor start,Rattle,Knock,& Post #2.

 

[CoastyAV8R]

For me it was hard starting when it was warm, others see performance issues/smoke.

 

[rbattelle]

Increase in oil level and diesel-smelling oil.

There are lots of different symptoms; not everyone experiences the same.

Ryan

 

[Jeremiah]

It will get increasingly hard to start when the engine is warm. Sometimes you might have to crank on it a minute or two (not a good thing either) before it will finally cook off. Once it's running, it seems to do OK. As far as I know, the only way to isolate an injector issue is to have the dealer or diesel mechanic do a leak-back check under pressure. The dealer might want to do a thing or two before that, but keep insisting they check all injectors too. Another thing: a dealer likely will replace the bad injector with a rebuilt one. Mine is doing OK after 20K miles.

 

[CoastyAV8R]

That's exactly what happened to my truck, hard to start when it was warm and ran fine when it did start. You can also isolate each injector by doing a injector return test. I did this to mine and found 2 of them were returning too much fuel to the tank and not allowing the rail pressure to build up enough to let the truck start.

 

[TCDiesel]

That's exactly what happened to my truck, hard to start when it was warm and ran fine when it did start. You can also isolate each injector by doing a injector return test. I did this to mine and found 2 of them were returning too much fuel to the tank and not allowing the rail pressure to build up enough to let the truck start.

Yep... . you got lucky. The jury is still out on the other 4.

 

[CoastyAV8R]

Yep... . you got lucky. The jury is still out on the other 4.

Twest, your a smart man and you definitely know the CTD but what you may think of as luck, I think of as troubleshooting. There are proven methods out there to isolate a bad injector and with a little effort it's not hard to do. If I had over 150,000 miles I may have just yanked them all and have been done with it but when there are trucks out there that have gotten well over 200,000 miles out of the original set of injectors why wouldn't a person spend a bit of time to troubleshoot a truck with only 80,000 miles?



For some folks, they don't have the time, the patience or the confidence to do it and thats cool but ultimately they could be replacing injectors that had many miles left in them. I work on aircraft and the mindset in aviation is that you don't just huck parts a problem and see what works and I carry that over to how I work on my vehicles. It makes good financial sense as well as definitively identifing the problem by troubleshooting it, then I know what the problem was and I don't drive off thinking "I spent alot of money, I hope I got lucky and fixed it".