8V71 smoking badly

[JohnEd]

A friends 71 smoke a little at start up but then clears up on fast idle after only a minute or two.  That seems normal, from what I have heard around here.  After he gets going down the road for only a mile or two, there is a HUGE cloud of white smoke that comes out of the pipe when he accelerated and the engine winds up.  This is a thick cloud and it reeks of raw diesel and will infiltrate the climate control system on a Lexus.  Don't ask how I know that and don't tell my wife.  She will find out soon enuff.  Believe me!

I was told that this is a symptom of a stuck injector and that the "white smoke" is unburned fuel.  This all goes away after five or ten miles in traffic.

Any advice for him?  I expect he will be joining the board soon and can ask his own questions but he is in the midst of personal turmoil and it may be a while.

John 

[Blacksheep]

Sounds like he may have had it idling for a long time before heading on his way and oil has accumalated to where it is now being burnt with the fuel. Almost like a run a way! Happened to me ONCE and I was sitting still. Had it idling for a while and when I stepped on the accelerator, it ran WFO until the excess oil was burned off!
Could be the same thing, then again...
If it hasn't been idling for long periods, look elsewher but that would be my guess. Oh and there is a definite mechanical issue to cause it to overload with fuel.
Ace

[Airbag]

My 71 smokes the first minute after driving away but stops right away and the smoke is a blueish color meaning oil. You old timers correct me if I'M wrong please. White smoke means coolant. My bus will puff some black smoke under a load, black is fuel. Am I right?

[JackConrad]

I was always told black smoke=incomplete or partial combustion of the fuel, bluish grey smoke=oil burning, white smoke=unburned diesel fuel, steam in the smoke=coolant.  If it reeks of diesel fuel, I think it would be raw fuel. 2 possible causes I can think of are;  a stuck or leaking injector or a cylinder with low compression that is not creating enough heat to ignite the fuel. Once warned up by driving a couple miles, the heat in the block helps the low compression ignite the fuel.  i would start the engine, then check the temperatures of each exhaust port on the exhaust manifolds as the engine warms up. If you have any cylinders that are cooler than the rest those are your problem cylinders.  Jack

[Airbag]

I was always told black smoke=incomplete or partial combustion of the fuel, bluish grey smoke=oil burning, white smoke=unburned diesel fuel, steam in the smoke=coolant.  If it reeks of diesel fuel, I think it would be raw fuel. 2 possible causes I can think of are;  a stuck or leaking injector or a cylinder with low compression that is not creating enough heat to ignite the fuel. Once warned up by driving a couple miles, the heat in the block helps the low compression ignite the fuel.  i would start the engine, then check the temperatures of each exhaust port on the exhaust manifolds as the engine warms up. If you have any cylinders that are cooler than the rest those are your problem cylinders.  Jack

Jack that sounds right. May I suggest a trick that we use for trouble shooting airplane engines. That is to get a spray bottle of water and just after shut down squirt the exhaust stacks with a very small squirt of water and the cold one will be obvious.

[NJT 5573]

If its not using coolant, its probably just a typical 8V71. The 5 or 10 miles is just letting it warm up. I have seen the old 8V71 T's at 400 HP take 50 miles to clean up pulling 80,000lbs.

Chances are it doesn't have any shutters to control the coolant temp so it never warms up real well unless it gets on a long pull, so it is still loading up as its being driven. The driver can control some of this by hitting the governor every shift right out of the yard, that's why your supposed to slam your hand in the door.

I'd hit the governor and even hold it for about 5 seconds or more or at least until it cleaned up, then I'd probably drive it as close to the governor as I could in 3ed gear on the highway until it has completely cleaned/warmed up.

Hitting the governor also seals the fuel system until the next time you service the filters or run it out, and its always nice to know its gonna keep running when you leave the yard.

Running it against the governor in first gear every time you start out until it cleans up is how I have always driven this engine, otherwise they can take a lot longer to clean up the exhaust.

The 8V series will never pass the Lexus test, no matter what. Put the Lexus in front of the 71!

I'll also guess that you friends 71 still has some healthy injectors in it and that it will still run over the pass pretty good. Most shops now days will confinscate those and give him some that don't smoke or run over the hill.

[JohnEd]

NJT,

Really a great post.  Thank you....really.

I will have my friend do the ex manifold test also and post the results.  This may take a couple weeks.

Be well, 

John

Also, that is some by line!

[Dreamscape]

NJT, I agree on your excellent post! Very well said. It takes a few more minutes of hard driving to warm ours up after I first fire it up. It'll smoke at first, but when she warms up it's gone, until I put my foot into it then it's a black smoker.

Paul