White Smoke When I Let Off

bilbo

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I haven’t been around here much lately other than lurking. The truck has been just running so I haven’t needed to! While on a trip to go pick up some pets for my other truck today I noticed a drop in power and EGT trending about 200 degrees higher than what I’d say was normal. This was for all conditions, idle seemed about normal temp and was nice and smooth like usual.

It also felt like the truck was missing when trying to hold a speed (cruising load), and the exhaust seemed hazy. When I would suddenly let off there was a puff of whitish smoke out the tailpipe. The truck was empty.

The injectors and IP are of unknown vintage and the truck has 302,000 miles.

I saw a thread that suggested that the fuel filter may be the issue. It’s been about a year for that but I wouldn’t think a clogged filter would cause elevated EGT.

In that thread someone had those symptoms due to problems with the advance mechanism in the IP. There’s a test for that, I’ll work on it after I finish up my other truck. What other things could I check on? I am good with dropping money on a pump and injectors, if there’s a way to isolate and test to confirm they are the problem. Otherwise that’s a lot of money to just throw at it without knowing for sure it’s bad.
 

bilbo

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I haven’t yet but that’s the first thing I’ll look at once I get to work on it. The change happened suddenly, it was running fine then I tried to merge onto the freeway and noticed the EGT, and the missing after I set the cruise.

I’ve got a timing meter just need to find it. I moved a year ago and still don’t feel like I’ve completely unpacked, and can’t remember where I put things that I did unpack.
 

Shadetreemechanic

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Sounds like you need a pump. Check for drips on the driver's side of the pump around the advance piston. You can test it by pushing the advance piston at no load idle. The truck should run worse. If nothing happens, that is your issue.
 

hacked89

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Kinda odd. White smoke is your getting incomplete combustion and/or coolant. a 7.3 at even 3-4 degrees runs pretty well. Near 0 it starts to get rough and whiter. Do you have infrared? You can check the temps across the cylinders. If it’s all relatively even something may have gone wrong in the pump.
 
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bilbo

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I always thought retarded timing caused higher EGT as the combustion event occurs closer to the opening of the exhaust valve. That may be wrong with diesels, I don't know for sure. I did try pushing the advance piston yesterday while idling. It definitely made the engine run poorly when I pushed it in. Cold/hot/whatever it starts right up and idles like nothing's wrong except for a very light haze from the tailpipe. The sun has to be just right for me to see it.

When I get some time I'm going to set up the timing device and check that. Seems like when it rains it pours; the CV axle went out on my newer truck so that's why I've been driving this one. It also needs to go into the body shop but that may have to wait now. Good thing I have the Ranger for my short work commute, but it doesn't have AC. South FL isn't a place to be without AC for any length of time.
 

Black dawg

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Check timing. Pay attention to timing at idle vs timing at 2K.

Retarded timing does cause higher egt.
 

Cant Write

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What about sudden air intrusion? He mentioned missing bucking under light load (cc) and then the puff of whitish smoke, could that be unburnt fuel.

I am fighting very near this exact issue. I was gonna start my own thread but I will definitely follow this one and attempt not to hijack.

Mine also acts fine with the occasional hiccup/miss/buck while cruising, very light and no associated smoke.

But if I work the injection pump hard, climbing our Mtn pass (direct, 40-50 mph).....once I crest and let up, the smoke show begins, it’s bluish-white-ish. No smoke coasting, but the lightest application (1/8 throttle) buck and jump in coordination with smoke plumes. Then if I hammer the throttle to kick it down.....whoa it will white/blue smoke out the sun and then start dumping black smoke.

I figured it was air intrusion........?

And sorry, I have been up for over 20hrs with shift. |sleepy I need to study and read the stickies.
 

hacked89

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Check timing. Pay attention to timing at idle vs timing at 2K.

Retarded timing does cause higher egt.
I’ve seen some conflicting personal experience and data but I would generally say you are correct and edited my post regarding retarded thx
 

bilbo

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I tried to check my timing today but the timing unit didn’t work. I have the DTI Tech-Time. Initially it would read rpm but no timing event. I cleaned and reinstalled the clamp on the fuel line and it read -20 regardless of RPM. I took all the probes off and reinstalled them, and now I can’t get it to display RPM. After messing with it for an hour I got frustrated and quit. I’m about ready to light the thing on fire. I’ve used it a few times before and it worked fine until now.
 

Brian VT

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I seem to remember that the order of things matters. Was it to leave the unit off until after you start the engine? Or turn the unit on and let it settle and then start the engine? I remember something like that that wasn't in the instructions but seemed to matter.
 

bilbo

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It does matter, the manual cautions against connecting the magnetic probe before the unit is powered up. I cleaned and reconnected everything one more time and it shows ROM now but timing is always -20.
 

bilbo

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Ok got it to work, it’s at 10.4 at 2000 RPM. I was hoping it would be further off.

Next I figured I’d check each injector line to see if there’s any effect on idle. Not sure what else to check.

I was also going to check the fuel supply pressure to see if the lift pump was working. It didn’t register anything on my gauge; I figured I’d pull the hose and crank it to see if anything comes out.
 

bilbo

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I replaced the fuel filter this morning, filled it with diesel kleen and ran it for 30 seconds or so to hopefully get the cleaner to the injectors and let it sit for a while. Maybe it will clean things up enough to run for now, assuming that’s a contributing factor. It was due for a filter anyway.
 

Nero

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That is a trick lots of us have used in the past with good results. I've also heard of some people doing a mix of atf in there too, the cleaning packages really get crud loose.
 
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