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sneaky · 07-14-2020, 09:46 PM

Have a 2003 Bounder with a 7500 diesel gen, has 4500 hours on it. Do regular oil changes and changed fuel filter this year. When first started, it smokes quite a bit, gray/white smoke, after a few minutes it stops and only a small amount of blueish smoke is seen. Has good power and runs 2 roof air with no problem. Wondering why it recently started smoking?
What to check?.

96 Wideglide · 07-14-2020, 09:59 PM

How about the air filter?

sneaky · 07-14-2020, 10:03 PM

You think an air filter would suddenly cause it to smoke for a few minutes on a cold start up?.
It has not been changed in at least 2 years.
Oil level does not drop and there are no fuel leaks at the Gen.

96 Wideglide · 07-14-2020, 10:17 PM

Could be bad glow plugs, but the smoke usually goes away before 2 mins run time.

hewebb · 07-15-2020, 06:03 AM

Usually white smoke is a sign of a lean mixture. Blue smoke at start up could mean leaking valve guide seals.

edgray · 07-15-2020, 06:45 AM

Since you said it isn’t consuming oil, perhaps it needs new injectors after 4500 hours. Smoke after warm up can be caused by incomplete combustion, usually caused by weak injectors creating a poor spray pattern.

sneaky · 07-15-2020, 07:04 AM

The smoke at initial start up is considerable, after a few minutes of running there is almost none. The minimal amount after startup I am not concerned with, it does not use any oil or go up in level from leaking injectors, it's the cold startup cloud I am worried about. If bad injectors, they don't seal up when you run a few minutes.. 4500 hours on a Quiet Diesel gen that's 17 years old really isn't much considering it sits idle for about 7 months a year here in NY, but is started and run every month under a small load to exercise.

twinboat · 07-15-2020, 07:24 AM

With glow plugs, there is one for each cylinder.

If one or more are bad, the engine will start and burn clean on the cylinders that they work on and smoke on the cylinders that are still cold.

You can check each glow plug with an ohm meter, after removing the wire.

sneaky · 07-15-2020, 07:39 AM

I've checked and changed them on my Duramax truck.
This is starting up between 80-90 degrees here, so probably not even needing the glow plugs to warm up cylinder. Gen fires off as fast as a gas model now, if plugs were bad, wouldn't it be harder to start?.

twinboat · 07-15-2020, 07:54 AM

Quote:

Originally Posted by sneaky

I've checked and changed them on my Duramax truck.
This is starting up between 80-90 degrees here, so probably not even needing the glow plugs to warm up cylinder. Gen fires off as fast as a gas model now, if plugs were bad, wouldn't it be harder to start?.

Offering simple , free things to check.

I have a marine diesel that will not start, on a hot day, without glow plug heat.

sneaky · 07-15-2020, 08:03 AM

Understood, but as I said, it fires off fast after it primes. Will ohm out the plugs, easy enough to do.
I thought white smoke was a sign of air getting in the fuel system, but there are no fuel leaks anywhere, and it would be hard to start if air were getting in somewhere I would think, and it would not go away in 5 minutes?.

Mr Lars · 07-15-2020, 05:33 PM

Generally, white smoke at start up on a diesel indicates a cold engine. You mention it clears up after a minute or so, considering the hours ( over 4000), I wouldn’t worry.