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Old 11-21-2009, 09:18 PM   #1
wdbowers's Avatar
Join Date: Feb 2008
Location: Mcminnville, TN
Posts: 33
Year: 90
Coachwork: Ward
Chassis: GMC
Engine: 8.2 Detroit
Rated Cap: 70
Why is my bus smoking?

Hey, my 1990 GMC chassis 8.2 Detroit puts out some white smoke when it is first started after sitting. Let her sitand idle to warm up and it seems okay. Then when you put the pedal down and pull out it makes a cloud that rivals the misquito man! This usally lasts for about a half mile then it turns to a normal amount of black smoke. Drive to the campground and stay a week and it is still okay. Whats up with this? Can it be damaging. Can it be prevented? How long can fuel stay in the tank without getting stale?
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Old 11-21-2009, 10:06 PM   #2
Bus Crazy
Join Date: Feb 2009
Location: Austin, TX
Posts: 1,489
Year: 1996
Coachwork: Thomas
Chassis: International
Engine: DT466/AT545
Re: Why is my bus smoking?

After warming up is the smoke still white on accelleration, or is it black? If black, it may be time to pull out your fuel injectors and get them tested. Could be you have a bad spray pattern and/or poor atomization. The shop in my area will test them for free, and usually it's not a big deal to pull them out. Just be sure to check and see if they have sealing rings (compression washers) on the bottom of the hole and pull those out with the injectors. Replace with new washers when reinstalling. I'm not familiar with the 8.2, but I doubt you have electronic injection on a 1990 model, so the cost for new injectors would probably be reasonable.
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Old 11-22-2009, 11:55 AM   #3
Bus Nut
Join Date: Aug 2007
Posts: 755
Re: Why is my bus smoking?

White smoke usually means unburnt fuel. I would try taking the bus out on the highway and running it good for a couple hours and see if that helps. If not I would try disconnecting the fuel line and running the bus off of a 5 gallon can of new diesel fuel and see what difference, if any) that made.

Here are some notes I picked up along the way concerning white smoke:

White smoke is unburned fuel, lots of it. This can be because the pump timing is retarded too much (late injection), sticking injector nozzle(s), lower fuel delivery pressure (not commonly) or just plain old bad fuel that won't burn. Obviously, any time you have smoke, compression loss is a possible factor, but generally you would suffer from a hard start condition when cold, or cylinder misfire as well.

Get a couple gallons of NEW diesel in a container and drop a hose from the filter inlet into the new fuel and try that before you drain the old stuff.

run it on the hiway to heat everything up and get all the condisation burnt out to see if it still blows white. could be a injector getting sticky.

Add about 10 gallons { 38 liter } diesel fuel to the tank plus get fuel treatment the same time that will useally clear up a bit.

When my bus sat a lot and only got warmed up while parked every few weeks, the same problem developed. Scary amounts of white smoke. Seriously scary. A long road trip last summer seems to have cured it so well that I had almost forgotten I ever had the problem. I also use 2-stroke motor oil at 1 oz per gallon
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Old 11-22-2009, 06:08 PM   #4
Bus Nut
Join Date: Sep 2009
Location: MASS
Posts: 449
Year: 1993
Coachwork: THOMAS
Engine: CAT 3116
Rated Cap: 83
Re: Why is my bus smoking?

Its a Detroit Diesel. Enough said. They like to smoke and leak. Replacing injectors on those engines was not an uncommon practice.

Definately take it out on the highway and run it for a good 3 or 4 miles and see if it clears up. If not you will be most likely looking to replace injectors down the road.
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Old 01-04-2010, 04:18 AM   #5
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Join Date: Dec 2009
Posts: 1
Re: Why is my bus smoking?

I recommend getting a couple cans of diesel purge put them in a clear container to get the result you want.
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Old 01-04-2010, 09:40 AM   #6
Bus Crazy
Join Date: Feb 2009
Location: Austin, TX
Posts: 1,489
Year: 1996
Coachwork: Thomas
Chassis: International
Engine: DT466/AT545
Re: Why is my bus smoking?

If you decide to get the injectors tested, I recommend you take them apart and clean them up first. That way, if they test poorly, you will know it's due to wear and tear, and not build-up of gunk.
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Old 01-04-2010, 10:03 AM   #7
NewSkewlHauler's Avatar
Join Date: Feb 2009
Location: Goodland, KS
Posts: 233
Year: 1988
Coachwork: Bluebird
Chassis: GMC
Engine: 8.2L Detroit N/A, Allison
Rated Cap: 65
Re: Why is my bus smoking?

Just bought my bus with the 8.2L Detroit in it. It has ALWAYS started regardless of the temperature (without heat or ether) and how long it's been sitting. So far it's been a wonderful engine. But when it's cold outside or been sitting for a few days, mine smokes at start up...and does until it gets starts to idle evenly. I'm told that this is just an 8.2L Detroit thing. As long as it clears up when the motor gets warm, it's something to monitor, not freak out least that's the stance I'm taking with mine! Once she's warmed up and running down the road, there's no smoke.

The Diesel purge or some fuel treatment probably wouldn't hurt either. I haven't done either of those things because I've run through several tanks in the 2000+ miles I've put on mine since December 21st! I'll likely do that now that she'll sit for a few weeks before I drive her again.

That's just my 1/50th of a dollar.
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Old 07-21-2012, 07:42 PM   #8
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Join Date: Jul 2012
Posts: 1
Year: 1987
Coachwork: GMC
Engine: Detroit Diesel 8.2L
Re: Why is my bus smoking?

Huge question my friends. I have a Detroit Diesel 8.2L engine in my bus. It smokes terribly with white smoke when driving at first. I mean a hell of a lot of white smoke, but after a few miles the smoke is completely gone....but then when we stop and sit for a minute and then get up and go it sometimes starts the white smoking all over again. The engine was completely rebuilt recently with all new parts and gaskets. Heads resurfaced, with new pistons, and even new fuel injectors are in the bus and were timed. Please give me a quick fix for this problem even if just for a day. I have an event with this bus that requires me to use it. Bus runs great with no missing but I can't have a cloud of smoke behind the bus as it is ambarrassing for business. Thanks so much for your prompt attention.
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