Injector Life

[Subzilla]

I purchased my Sub at 130k miles and now have 252k on it and have never replaced the injectors. So that's 122k miles plus (from previous owner) on the injectors. They tested fine (by a professional) about 12k miles ago but I just can't help to think that they are the culprit of the following symptoms: rough idle, constant white smoke (at least I think it's white), and harder starting. I've done all the usual stuff: new fuel filters, played with the timing, changed air filter, new IP about 20k miles ago... I'm thinking I should have them checked again or should I pursue another route? Maybe my engine is getting tired?? Any thoughts?

[john8662]

How were the injectors tested?

At that many miles, they will still work but will be spraying early and the nozzles will not be spraying true.

When testing the injectors, they will have to take note of the pop pressure, not just whether it's spraying fuel or not. The lower the pop pressure, the worse the performance, the more worn the injector (spring) is.

I can't recall the pop pressure number off the top of my head, but I think it's 1900 psi and 2100 psi for 6.5.

[Subzilla]

I sent them to Tim Wagner at Accurate Diesel and he said he pop tested them and checked spray pattern. Can they deteriorate in 12k miles?

[john8662]

Your injectors are likely ok then if they were pop tested and passed the test. I have faith that Tim knows how to test injectors properly.

I don't think that your injectors have failed in the last 12k miles, unless they got contaminated during installed, etc.

For the symptoms you're describing, a compression test would be a good base line to know what the condition of the engine is.

[Subzilla]

I definitely don't dispute you on Tim's ability. He's been very helpful and knowledgable every time I've dealt with him.

I've thought about doing a compression test as I've never done one on this vehicle. I'm a little afraid to for fear of bad news. I really wanted to make it to 300k miles without rebuild but maybe this might be my excuse to the wife to sneak an Avant or Pennisular HO replacement into the picture.

[john8662]

Start with the compression test, this will let you know if things are decent enough to try and do some surgery on the engine.

The other thing that I can think of that will cause white smoke at idle is that the timing is retarded severly, which would mean that perhaps you'll be interested in upgrading to the timimg gear set, or freshen up the chain with a new one.

To make sure that you're not getting the rough idle, etc. from air in the system. Try installing a piece of 1/4" clear tubing on the injection pump fuel return line. This is the line that comes directly out of the top of the injection pump. Install the clear line, start the engine and watch for bubbles. When the engine starts running poorly, observe how much air travels though the tube. You should not be able to see any air going through the tube after the engine has been running. If you do, then you have an air leak in the fuel system somewhere that is contributing to the poor running condition.

[Subzilla]

I installed the DSG gears when I installed the new IP. The timing was retarded so I played with it back in October and ended up advancing it to where I just start getting the "rattle". Someone here suggested a method to activate the HPCA with engine warm and listen for the rattle to kick in. After shutting off the HPCA, the engine should go back to "6.2 quiet", then call it good. That did improve performance and smoke reduction, then, but it never really eliminated it.

I'll check for air in the system, then go for the compression test.

Thanks for the replies, John. And to Jim B, I love the instant e-mail notification that a reply has been posted to your post. Very cool and keeps me from having to check the forum every 15 minutes for a response.