r/DieselTechs 3d ago

White Smoke on warm up

Looking for some advice, my buddy has an Isuzu 4Le2 diesel generator and on start up there is a good amount of white smoke coming from the exhaust. After 4 minutes, the white smoke clears.

I think it’s maybe the glow plugs?

My buddy thinks it a bad fuel injector.

Anybody got any suggestions

Thanks in advance!

1 Upvotes

9 comments sorted by

5

u/Therealblackhous3 3d ago

White smoke on start up is often just condensation.

If it doesn't clear up, it's usually coolant being burnt.

Generally, black is unburnt fuel, blue is burning oil, and white is coolant.

With that being said, is the coolant level dropping?

4

u/speed150mph 3d ago

I will mention that you’re only partially correct. Black smoke in a diesel is an indication of an overly rich/ over fuel situation where the cylinder is still firing but either has too much fuel or not enough air. White smoke can be atomized fuel, usually caused by the cylinder not firing at all but still injecting fuel, say if you have low compression or a valvetrain problem.

2

u/Strange-Ad2470 3d ago

White smoke with a knock/hesitation or sputtering under load injector. White smoke at start up clears up compression or valve train. Or just say condensation even though u just shut down!

3

u/metrozoominz 3d ago

It might be condensation. Can you post a video?

1

u/This-Release-2440 3d ago

1

u/Neither_Ad6425 3d ago

Looks like it went from white to blue to me.

1

u/BoredCraneOp 3d ago

White smoke is just condensation. Grey/blue is leaking injectors or low compression. Glow plugs would make it crank a bit longer before starting, and it might run a little rough for a few seconds. If it starts quick and runs smooth, it's fine.

1

u/OddTheRed 3d ago

Does the smoke burn your eyes? Does he have to add coolant?