7.3 IDI Terrible smoke

[Brody]

Hi everybody,

My friend has a truck that we picked up a few weeks ago. Would barely start when we got it. Push button glow plugs, ungodly amounts of rancid white smoke coming out the exhaust and was popping and farting all the way home. Pretty much a mosquito fogger.

Anyways, I pulled the injectors when I got it to the shop, 7 of 8 were bad with leaks and pop pressures off. So I figured hey that must be the problem right? Nope, once I got the new ones back in it still smokes like a piece of crap, absolutely acrid white/grey smoke all the time. I put clear lines on parts of the return system once I got new hoses on there and there wasn't/isn't any air getting in. It starts super easy now and has pretty good power but still pops just a little bit at 2700 rpm or so. Adjusting timing doesn't do anything and neither did turning down the fuel.

I compression tested it and that checked out ok. Pulled the valve covers off looking for a bent rocker arm and those were fine. I'm running out of ideas here. The injection pump is original so I'm not too sure if that could be the culprit. I started it the other day maybe 40 degrees out and it fired right up without the glowplugs and it idles beautifully. It just pours the white smoke the whole time it runs relentlessly. Nothing I've done has made even a slight change to the smoke.

Ideas anyone?

Edit: Before anyone says headgasket it's not using coolant and there's none in the oil etc. Just rancid raw diesel coming out the tailpipe

 

[nelstomlinson]

Maybe

Just rancid raw diesel coming out the tailpipe

It's definitely unburned fuel?
Try giving it the ATF treatment?

 

[cardana24]

Have you checked the timing?

 

[lsaami]

where did you get the new injectors?

 

[MtnHaul]

Did you replace just the 7 injectors you noticed as bad or did you replace all 8?

Does the smoke dissipate quickly or does the cloud linger?

Also, when you say you checked the compression what were the numbers?

 

[Philip1]

White/grey diesel smoke makes me think its either bad timing (which can be very difficult to time by ear) or not enough fuel to properly atomize and ignite the fuel.

 

[Brody]

So I don't have any equipment to time this thing properly. I do know that the bottom two bolts on the injection pump were already loose when I went to move the timing a bit.

White/grey diesel smoke makes me think its either bad timing (which can be very difficult to time by ear) or not enough fuel to properly atomize and ignite the fuel.

I'm curious about this not enough fuel idea. Are you thinking a bad lift pump or injection pump?

I have been filling the filter which has been on and off a few times during this process with atf and seafoam. The thing that is really perplexing is how there has been zero improvement in the smoke. When the truck would barely run and stalled out turning hard + had air intrusion it smoked just as bad as it does now. Now it will start without glowplugs in 40 degrees and runs and idles smoothly. I have an injection pump on my truck that I'm probably going to end up swapping.

I did all 8 injectors. The smoke is heavy and hangs around for a while. The previous owner was a hack. He punched a 1 inch hole right through the firewall where they like to crack/flex from the clutch master.

 

[Selahdoor]

I would suggest that you put aside what you think the timing is, and set the IP up by the thickness of a couple dimes, and see what happens.

To do that, you turn the top of the IP toward the passenger side. I'm sure you know about the marks that are used for this. In fact, can you get a pic of those marks for us?

Make sure those bolts are tight when you finish.

This is an easy thing to do, and you'll see the results right away.

 

[nelstomlinson]

This does start to sound like timing or injector issues. Factory new injectors and most rebuilts have problems. Did you put the new ones on a pop tester? If they were popping at close to the same pressure, then move on to timing.

If there were two loose IP bolts, that suggests timing could be way off. Someone who knows more than I do could probably suggest how far in what direction you should try tweaking the timing.

I have a timing meter I bought on ebay. I believe it is the same Draf Industries one that the Navistar manual calls for. It's under $300 there. As far as I know that's the only option that doesn't involve buying old, dubious electronics sight unseen.

Edited to add: Selahdoor already chimed in with the what direction and how far. Might be worthwhile to tweak it that direction a dime-width at a time until it is plainly not running right, then come back a bit until it sounds better.

 

[Selahdoor]

Yep. I wish that I had gone there right away, on my own. Instead I spent months tweaking this and that and the other, trying to figure out the smoke.

Finally just set it up by a couple dimes thickness. Was a bit better. Went back half a dime, got worse. Ended up with about 2 and a half dime's width, and the smoke and rough running disappeared.

The smoke I was dealing with was also acrid. Mostly white. Some greyish. And lots and lots of it!

Here is what it was running like:

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Shows the smoke at the end of the vid.

Here it is, after adjusting by two dimes:

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I said 2 minutes.... It hadn't even been 15 seconds.

I turned it back a half a dime after that. Then turned it from there back up another dime, for a total of 2 and a half dime thicknesses in the end. That cured my problem.

 

[MtnHaul]

Shot in the dark here, is the diesel in the truck fresh? Old contaminated fuel might be a factor.

 

[Brody]

Selahdoor: I probably had the timing in about 5 different spots varying from from a couple dimes to all the way over. Your smoke looks exactly like what the truck is doing. Maybe I need to try a few more times with it.

MtnHaul. I assume when we filled the filter with fresh diesel and ran it for 10 minutes off the jerry can full of clean diesel it would've cleared up some if that were the case but there was zero change. Nothing I've done has changed the smoke.

I will mess with the timing some more this weekend. I'm not at the truck currently.

 

[nelstomlinson]

Maybe one of our pump experts can chime in here. I think I remember that there are potential issues inside the pump, things that can stick or springs that can break?

 

[ih8minimumwage]

Does it look at all like the IP gear cover was off (any orange RTV there?). Someone could've got into it and put it back together a tooth off, which would explain the loose IP hardware.

Any differences when cracking injector lines?

 

[Brody]

Does it look at all like the IP gear cover was off (any orange RTV there?). Someone could've got into it and put it back together a tooth off, which would explain the loose IP hardware.

Any differences when cracking injector lines?

It had 1/4 inch of grime on it and orange RTV. The previous owner was a strange one. I think the bottom two were loose because of laziness lol. The top one was nice and snug.