Bad injector?? Using a digital infra-red thermometer & interpreting injector temps

[Brad S.]

Pretty sure I have a bad injector, little blue smoke at idle, slight shudder at idle, etc.
I bumped the timing up a little, (done by ear) not sure if that helped much, sounds better.
(I know could be a problem in pump or timing, gonna try this first)
The local school district I drive for has a digital infra-red thermometer and I plan on using it on the injectors to test temps.
Felt the top of the lines after a short drive, didn't have one that was much hotter then the rest.
If I take readings how much difference can there be in temps, before a injector is considered faulty???
Thanks for your thoughts.

 

[SparkandFire]

I would suspect a "smoking gun" for a stuck-open injector. Line would be very hot. Not really a marginal thing, if it is staying open and combustion heat is coming back up through the line, you would see a drastic difference in temperatures. I would not declare an injector failed on a few degrees difference between the others, as there are areas on top of the engine warmer than others.

I had one injector hang open before I replaced them all, it was "burn the hell out of your finger like a soldering iron" hot.

 

[snicklas]

I have also heard that a stuck open injector can get hot enough to deform or melt the return cap on the suspect injector..... never seen it, but have heard it talked about on here.....

 

[smokinpipes]

Just posting my experience.. but you can crack the injector lines one at a time while it is running and listen for which cylinder changes least and that could be your suspect faulty injector.
I had a similar issue, but it turned out one, and only one, injector had coking in the head of the engine, causing a slight lope, missing sound with associated blue smoke at idle.
Upon replacing the injectors, and checking the bores, I found the coking, removed the carbon build-up and reinstalled the old injectors for fun and it resolved the issue. Ended up replacing them anyways, but I'm too curious to not ask "what if".

 

[Can30Diesel]

I had an injector stuck on my truck. It sounded like a dying alternator bearing at first, then it smelled like diesel and started smoking. Happened while I was crossing a big bridge with slow people in front of me.

When I finally got to pull over and pop the hood, the dead injector had heated up so much that it melted the return cap completely. Liquid plastic had gone through the return line to the next cap in line and melted inside of it, sealing it. It was a fun day for sure! I've since replaced all my injectors and have a new return line kit on.

 

[riotwarrior]

In all likely hood you don't have a stuck injector but a weak one popping too soon and that's causing the fuel smell as it's not able to fully burn.

Cracking injectors will help determine which is problem but a stuck injector will get hot from my understanding.

Hope that helps...

JM2CW

Al

 

[Brad S.]

Thanks guys,
Did some crackin of injector lines and found #8 cylinder was causing some of the smoke and some of the shudder.
Thinking maybe another one might be a problem.
Gotta fix a passenger side front brake caliper, found that when I was reinstalling the turbo, took that wheel off to get at the exhaust manifold.
I suppose stuff tends to rust up when you dont drive it for 8-9 months.

 

[Zaggnutt]

Thanks guys,
Did some crackin of injector lines and found #8 cylinder was causing some of the smoke and some of the shudder.
Thinking maybe another one might be a problem.
Gotta fix a passenger side front brake caliper, found that when I was reinstalling the turbo, took that wheel off to get at the exhaust manifold.
I suppose stuff tends to rust up when you dont drive it for 8-9 months.

Did you end up resolving this? I am curious what you had to do to fix it. At warm up I have a huge cloud of white smoke just for a few seconds. I also have fuel in my oil. Not sure what I should be listening for when I crack the injector lines. I get the missing sound when I crack them but it's the same for all of them. What should I listen for?

 

[smokinpipes]

Did you end up resolving this? I am curious what you had to do to fix it. At warm up I have a huge cloud of white smoke just for a few seconds. I also have fuel in my oil. Not sure what I should be listening for when I crack the injector lines. I get the missing sound when I crack them but it's the same for all of them. What should I listen for?

Typically, I wouldn't be concerned with a fuel injector if you have fuel in your oil, but I'd be more suspect of a bad lift pump if you still have the mechanical unit mounted on the engine block, or a bad input shaft seal on your injection pump.

Word of the wise, buy a new lift pump, it's a much less expensive part to replace, that is more times than not the suspect for that.

White smoke, can be you have a bad glow plug, (if the the engine is cold, and it shudders/misses only for a few seconds) or it could be the injectors nozzles are worn out, but that will cause more smoke for longer periods of time after engine start up; and a rough, uneven idle.

Case in point, check your lift pump, and verify all your glow plugs are good first.. then report back.

 

[Brad S.]

Lol, yep the way I fixed this problem was by pulling the engine....(oil useage, blowby)
IIRC, I think I had a couple injectors that weren't spraying good enough, clogged or whatever. #8 cylinder is another story, keep reading below.
Also,think I pulled each injector on the passenger side and looked for carbon buildup, found one that looked bad, changed it and problem went away.
I was reading your thread about this problem.
The fuel in the oil like some said "should" be from a lift pump...????
If you can, (time wise, or if you need your truck for work etc.) pull each injector and take a good look. Would be even better if you could bring them somewhere to pop test em. Did this problem just come up lately????
I had a extra set of injectors to play with that helped as well.
After I pulled the engine & pulled it apart and the #8 cylinder had stuck rings.
As it turned out the machine shop had to sleeve that cylinder.

 

[Zaggnutt]

Lol, yep the way I fixed this problem was by pulling the engine....(oil useage, blowby)
IIRC, I think I had a couple injectors that weren't spraying good enough, clogged or whatever. #8 cylinder is another story, keep reading below.
Also,think I pulled each injector on the passenger side and looked for carbon buildup, found one that looked bad, changed it and problem went away.
I was reading your thread about this problem.
The fuel in the oil like some said "should" be from a lift pump...????
If you can, (time wise, or if you need your truck for work etc.) pull each injector and take a good look. Would be even better if you could bring them somewhere to pop test em. Did this problem just come up lately????
I had a extra set of injectors to play with that helped as well.
After I pulled the engine & pulled it apart and the #8 cylinder had stuck rings.
As it turned out the machine shop had to sleeve that cylinder.

Yeah I saw that installing the lift pump wrong or a bad pump could cause it. My pump has maybe 500 miles on it? Just replaced it. I added to the Oil in Fuel thread today after thinking about what could be connected. Noticed the puff of white smoke after it was sitting for a week at a hotel with air intrusion / blockage. I was trying to start it everyday so long cranking and not starting (figured out it was FSV) Once I was back to running it daily the smoke stopped.

I let it sit, installed manual valves (involved running new fuel lines to tanks and to engine) vc gasket, manual gp button. Had long cranking again til I got all the leaks/air purged. Big puff of smoke, truck shakes and hitches on idle. Hitch goes away, shake does not. Had air intrusion after manual valve install so went through the start then stall, half full filter, cracking and filling filter, cracking injector caps to purge, tightening return lines, etc.

 

[Zaggnutt]

Typically, I wouldn't be concerned with a fuel injector if you have fuel in your oil, but I'd be more suspect of a bad lift pump if you still have the mechanical unit mounted on the engine block, or a bad input shaft seal on your injection pump.

Word of the wise, buy a new lift pump, it's a much less expensive part to replace, that is more times than not the suspect for that.

White smoke, can be you have a bad glow plug, (if the the engine is cold, and it shudders/misses only for a few seconds) or it could be the injectors nozzles are worn out, but that will cause more smoke for longer periods of time after engine start up; and a rough, uneven idle.

Case in point, check your lift pump, and verify all your glow plugs are good first.. then report back.

I will check glow plugs, but I am more concerned with the fuel in the oil right now. Will the ip leak from the weep hole underneath if that cup seal is bad? Ip is probably original. Shoot, thought mileage was in my sig. 200k.

 

[Brad S.]

I'm sure you've read this before, but I'll throw my experience in as well.
Going to a electric fuel pump/ lift pump does help if you have some issues with long cranking or hard starts.
(I had similar issues) But if you do have other fuel problems that doesn't mean you SHOULD NOT fix/find the original problem.

 

[Zaggnutt]

I'm sure you've read this before, but I'll throw my experience in as well.
Going to a electric fuel pump/ lift pump does help if you have some issues with long cranking or hard starts.
(I had similar issues) But if you do have other fuel problems that doesn't mean you SHOULD NOT fix/find the original problem.

, yeah, I've read it a couple times. Definitely on the "To Do" list along with new injectors and a new ip.... Having fuel in my oil scares the hell outta me though so I would like to solve that first. Then once the money tree starts growing I can do the rest....

I've actually solved the hard start, long crank, start then stall, but it is still a little rough. I think some of the white smoke and the rough idle at start may be the manny gps because they don't cycle after the initial WTS time. Thanks a lot for your help.