Black exhaust

[jmacstack]

Hello all, I just came back from a weekend trip and I am continuing to notice that upon acceleration, I am blowing black exhaust. The engine is at operating temp and has been driven for hours. It happens no matter what the engine temp is and always after stopping at a red light or a stop sign. If I accelerate to pass someone for instance, I see a bit of black exhaust. While driving down the road normally, I don't see any exhaust. Is this normal? Is it a 2-stroke trait? It has always done it but for some reason I am noticing it is happening more. I'm sure to be the car stopped next to me and be receiving all this ugly smelly exhaust, can't be much fun! Any thoughts?

Jennifer

[fulltiming]

Accelerating a 2 stroke Detroit will frequently result in black smoke. The injectors dump more fuel than the blower and turbo can keep up with. The pre-DDEC (Detroit Diesel Electronic Control) models can be adjusted to max power (more black smoke) or less power (less smoke) fairly easily by adjusting the rack and the injectors. On DDEC models, the computer controls the amount of fuel injected. Yours is likely a pre-DDEC model but was built close to the time that Newell began using the DDEC Silver 8V92's.

A restricted air filter or misadjusted exhaust valves (a 2-stroke DD does not have intake valves) can both increase the amount of black smoke (unburned fuel) that is being emitted. Putting your foot into the throttle of a turbo-charged 2-stroke before the engine has had time to spin up the turbo will result in additional black smoke. That said, most DD 2-strokes do smoke when you accelerate. If your exhaust exists close to the driver's side, which most of the Newells do, it is easier to see the smoke in the outside mirror.

Bad blower seals will also cause large amounts of black smoke.

Keep a clean air filter, don't set the exhaust valves too tight so that they open too early, avoid heavy use of the accelerator and avoid idling will all minimize black smoke in the short run. However, 2-stroke DD's really like to be driven hard so the long term affect of gently driving the engine, lugging the engine or idling the engine will be build up of carbon inside the cylinders. The old adage of "drive it like you stole it" (as long as you wait for the engine to warm up thoroughly) is really a good idea. They used to say that when you get in, slam the door on your finger and that will put you in the right mood to drive a 2-stroke DD. The lugging or idling are both engine killers however.

[encantotom]

Michael is spot on.

I hope Wally chimes in here. he is the expert on this topic, having adjusted his rack to optimum power and smoke.

tom

[prairieschooner]

I have a Vacuum Gauge that lets me know if the Air Filter is Clogged or getting close. Mine is located in the Starboard Aft Switch Panel (the one at the rear and to the right) and has a small hose connected to the Air Filter Canister. I have noticed that Black Exhaust if I Accelerate too hard from a Stop, unburnt fuel. I try to accelerate a little softer from a stop and this has helped.
*As a side note, I have found the Black Exhaust to be fun when the guy next to me did something deserving, especially if he has that window down.

[fulltiming]

I left one other important variable out: altitude. The higher the altitude the thinner the air. A turbo increases the density of the air and the DDEC tries to make adjustment for altitude also (but only adjusts when the engine drops back to near idle). However, even with the turbo and the DDEC, 2-stroke DD's smoke more at higher altitudes. Nature of the beast.

Without DDEC and a turbo, you will get ALOT more smoke at higher altitudes.

[chockwald]

Michael, I noticed that at higher altitude mine did smoke more, so that is a confirmation to what you said. I, like Steve, try to start out a little easier from a stop, and that reduces smoke, but after that I drive it like I stole it!

[Wally Arntzen]

When I first got my 88 about 6 years ago I noticed that it smoked and took it to my mechanic friend. He informed me that he could eliminate the smoke but it would effect the power on take off. I had him do it and it really did effect it. It ran normal at speeds above 50 miles per hour but had nothing on the git go when leaving from a stop.
I took it back and had him reset the injectors and I live with the smoke. If you take off real slow you can do it without smoking and after about 100 yards you can punch it without having the smoke.
I feel bad when Im next to a car with the windows and hit it with a blast of smoke covering their car. I have had a few hand gestures thrown at me by unhappy folks.
It has nothing to do with the engine going bad, its just having an old 8v92 and you have to learn to love them.
Thats my story and i'm sticking with it.

[afrench45]

Hi all,
My series 60 smokes some too. No matter how cold or hot the engine is, when I take off, a small cloud of smoke comes out of the exhaust. Its not a bunch, but it is noticeable. However, I have traveled with two other Newells with 60 series and they smoke too, so Im thinking its just apart of owning a diesel!

[jmacstack]

Thanks for all your input! This forum is great! I will accelerate with gentleness from now on unless someone deserves the full blast and then I will drive it like I stole it!

Did any of you have any thoughts regarding my charging issues?

Thanks, Jennifer