What would cause a school bus to roll coal?

"Rainbow" (rainbeaux) 01/28/2015 at 10:02 • Filed to: None

0

12

Yesterday, I was following a school bus on my way home from work. All of a sudden, it started belching out a thick grey smoke. It wasn't quite as much as the bro-trucks like to do, but the same general idea. I had to back off quite a bit to let my car breathe. But anyway, yeah, I'm just curious what happened to this bus. It was fine before, and then it started smoking every time it accelerated.

ttyymmnn > Rainbow 01/28/2015 at 10:05

6

School district maintenance.

spanfucker retire bitch > ttyymmnn 01/28/2015 at 10:09

0

This.

Those fucking buses are never maintained. The only school buses that I don't see belching black smoke are the newly purchased ones. But given enough time, the same thing will happen to them, because they won't maintain them.

Boxer_4 > Rainbow 01/28/2015 at 10:10

1

Older diesels often smoke under heavier load due to a very rich air-fuel mixture.

Cé hé sin > Rainbow 01/28/2015 at 10:17

3

Overfuelling (more fuel injected than the engine can cope with) and no DPF.

SidewaysOnDirt still misses Bowie > Rainbow 01/28/2015 at 10:18

1

Old diesels tend to do that a bit more under a heavy load, and most school districts seem to buy cheap used school buses.

RamblinRover Luxury-Yacht > Rainbow 01/28/2015 at 10:19

0

I had to back off quite a bit to let my car breathe.

Wat

Anyway, smoke under accel on a diesel with a few miles is perfectly normal. You have slightly reduced compression (leading to less complete burning), and more tired injectors injecting into that reduced compression space - a little more fuel, a little bit less of it fully burned, and voila. Particularly with things loosening up as it warms up, but before it's all the way hot. It's also elementary to diesels that they need more fuel to accelerate than to continue to run relative to air - it's just how they work, and the natural phenomenon that lead to the rolling coal cult in the first place.

Rainbow > RamblinRover Luxury-Yacht 01/28/2015 at 10:21

0

I just mean that I don't feel like replacing my filter quite yet, and that would have destroyed it.

RamblinRover Luxury-Yacht > Rainbow 01/28/2015 at 10:23

0

Well, soot is less clog-multiplying than airborne oils, and you really aren't pulling that much air, but I suppose I see your point to an extent. Visibility =/= doom.

Brickman > Rainbow 01/28/2015 at 10:39

4

Too many fat kids making the engine struggle :P

gmporschenut also a fan of hondas > Rainbow 01/28/2015 at 10:47

0

http://www.autoblog.com/2009/07/08/car…

http://www.consumerreports.org/cro/cars/car-p…

deekster_caddy > Rainbow 01/28/2015 at 10:54

1

Over fuel? Heating oil instead of diesel fuel? Bad injectors? Generally poor maintenance? There are a lot of ways to make a diesel smoke. Some are just still cold... it takes a long time to heat up those big diesel motors.

pip bip - choose Corrour > Rainbow 01/29/2015 at 03:11

0

poor timing.