Archived Help....Truck smoking.

[AndrewKing]

HI Guys,

I was driving my work truck today ( A 1997 Freightliner MT 45 step van , Cummins 5.9 , 4 speed allison automatic, 3.3 Rear, 19K gvw, 272 K miles ) and it continues to lay down smoke (I hate to say it looks kinda bluish but the truck does NOT regularly burn oil) even when warmed up (temp gauge about 200 degrees, oil pressure a min of about 40-45 PSI at idle....Hard to say how accurate gauges are ) and only pressing mildly on the accelerator.

Outside temps probably upper 20's to low 30's

The truck is not loaded heavy (I only haul high bulk snack chips, cakes and some candy)....not even full loaded

Anyways, the truck typically smokes and misses / stumbles when cold (the smoke looks whitish upon start up, clears up after loping at idle for awhile (or if I push the accelerator the engine will speed up but then lay down grayish / white smoke after the engine reaches a certain RPM then it kinda feels like it is missing (the engine kinda "chugs" when it is acting up (almost like a gasser when it misses)).

FWIW - I realize that this Freightliner truck has NO heater grid and was NOT plugged in BUT my other truck w/ the 5.9 has inoperative heater grids and it does NOT lay down white / gray smoke like this one even in the cold when cold...Heck the other truck never "chugged" or stumbled even when only warmed up for a minute before gently driving off.

I know generally what the different colors of smoke means (white / gray - cold start , blue is oil burning, black is unburnt diesel) BUT what I can't figure out is the "missing" feel I get when I try to accelerate (the smoke only happens when the engine "chugs" or "misses").

In the past , I have had this problem before (interesting to note this only used to happening colder weather when the engine was cold BUT it it used to go away once the engine warmed up a little bit) BUT now (actually tonight) the engine came be up to temp and it feels like it still misses and will lay down a haze (hard to tell what color since it was dark out...I could see the smoke by the side mirrors and the headlights of the cars behind me) when driving easy....

Worse part was it did it this slight "miss" and haze the rest of the way home and now I'm worried I may not be able to use the truck for work tomorrow

I bought the truck used so I don't know the history of the injectors / injection pump etc...

I have changed oil regularly and every once in awhile some power service fuel additive.

Are there any tricks of the trade to figuring out what is wrong?

(the fuel filter was changed about 7 months ago....The truck is driven about 325 miles per week)....I just drove the truck the other day about 180 miles and it did exhibit some of the similar symptoms but not the more continuous "missing" that happened tonight (FWIW the truck got 10.3 MPG on the highway which is lower than when I first got it BUT I realize now is winter and the fuel may not be as good) ?

I may try to do a video tomorrow AM of the start up and chugging if that will help ( I can maybe put it on You Tube).

Thanks in advance for any and all help.

Andrew

PS - Is there anything horribly wrong (other than pollution / possibly breaking down ) of driving the truck like this (at least until I finish my work)....I really have to work BUT I don't want to damage anything and cost even more to fix.

 

[JR]

White smoke is most generally from fuel. I'm guessing it may be time to pull the injectors and have them pop tested. You may be due for some new ones especially if they are the originals. If you choose to continue to drive it keep an eye on the oil as a drizzling injector can dilute the crank case oil

 

[sg5054]

Jrs right. Skipping, white smoke is likely a injector(s) misfiring, leaking, dribbling fuel. Get it taken care of now as the damage from oil dilution from fuel will cost you a whole lot more than a set of injectors. Your descriptions have all the signs of this.
The fuel will be washing the oil off the cylinder walls which will destroy the pistons and rings. Fuel will end up in the crankcase and take out the crank and rod bearings. How much work are you going to get done if it is in the shop for a couple weeks getting rebuilt to the tune of $5K vs a day to get the injectors replaced.

 

[AndrewKing]

HI,

Thanks for the advice......I think I better be safe and get the injectors....Any advice on where to get them and if I should go new or rebuilt?

I don't need to hot rod around....I would like something that will last and get good economy ( I was looking online for injectors and in several places I saw where "performance" injectors can get more mileage AND power)....does this sound reasonable (I know good exhaust can get more power AND mileage BUT if you are just putting in more fuel for more power how can that get better MPG ? (I suppose if better fuel atomization then it may be possible)?

Thanks again....I will hold on ordering anything until I learn more.

Andrew

 

[sg5054]

If it was me I would go with stock injectors. This is a work truck not a toy. I don't see any value in trying to uprate your rig. Especially at 272K. It will last longer if you keep it in it's original configuration and become fanatical about maintenance instead. Besides, realistically how long do you plan to keep it? Will you have it long enough to truly reap the rewards of the mods? Get it fixed right off.
Good luck

 

[JR]

If your having a problem sourcing parts PM member MWilson he is the Freightliner (and everything else) parts guru. I do not know what is available for performance injectors in your configuration.

 

[Sticks]

9100 miles on the fuel filter. I'd say it's time to change it.

Look at your fuel heater/pump assembly. Pull the plug for the fuel heater, if it's wet, it (fuel heater) needs to be replaced. The symptoms are also indicative of air in the fuel, not always accompanied by a hard start condition.

Might also want to check your fuel pressure. Should be IIRC a minimum of 20psi at idle.

You can narrow down what cylinder is missing by cracking loose the injector lines one at a time (tighten each one back up as you go on to the next). When there is no change in the engine behavior, there's the problem child.

 

[AndrewKing]

HI,

Thanks for the input guys.....I'll spend most of tomorrow looking for leaks / air leaks that could be a problem.

Been reading a lot about injectors (in case there are no leaks and fuel pressure is good) but still cannot figure out if adding 215 injectors to an otherwise stock 180 HP or so truck would help with fuel mileage like the RV 275 injectors do for the 24V engines....Any ideas or experience with that?

Thanks!

Andrew

 

[Sticks]

Like everyone else, when upgrading you are pushing all the components (engine cooling, transmission, drive line, axle...) past design limits. It may or may not be able to handle it. Were it me, for a work truck that is my bread and butter, I'd keep it stock.

 

[LandShark]

I would first do a close inspection of the fuel lines. including the return lines and fuel pickup. I had a similar problem a few years ago and ended up replacing all the fuel lines with rubber lines to fix the white smoke and hard starting and missing. Also bypassed the fuel heater and installed a course inline prefilter. The lines showed no signs of leaking, but I was sucking in air somewhere. Problem has been fixed for 40,000 miles now, and truck continues to run great.