Brown puff of Smoke at start up... an Issue?

[teneicm]

Hello-

One of our Kubota 45 hp diesel engines just started producing a small puff of brown smoke right at start up. It immediately goes away and seems to run cleanly afterwards at all speeds. Does anyone know what this is caused by and whether it presents an issue (either currently or is a forebearer of other problems?)?

Thanks-

Matt

PS - May not be able to reply for a couple of days as we are moving down island and don't know where the next internet will come from....

[colemj]

Doesn't sound abnormal at all. Ours do this. It is most likely unburned fuel from the initial start. Are you sure they have never done this and you are just now noticing it?

Mark

[MARINE ENGINNER]

Originally Posted by teneicm

Hello-

One of our Kubota 45 hp diesel engines just started producing a small puff of brown smoke right at start up. It immediately goes away and seems to run cleanly afterwards at all speeds. Does anyone know what this is caused by and whether it presents an issue (either currently or is a forebearer of other problems?)?

Thanks-

Matt

PS - May not be able to reply for a couple of days as we are moving down island and don't know where the next internet will come from....

hi matt
have you noticed consumption of your engine oil?

[teneicm]

Mark-

No, its definitely something new. The other engine doesn't do it. It's been doing it for about 3 weeks now and seems to be causing no other ill effects.

Marine Enginner- I haven't noticed any unusual oil consumption. Everything else seems to be pretty normal.


Thanks- Matt

[MARINE ENGINNER]

Originally Posted by teneicm

Mark-

No, its definitely something new. The other engine doesn't do it. It's been doing it for about 3 weeks now and seems to be causing no other ill effects.

Marine Enginner- I haven't noticed any unusual oil consumption. Everything else seems to be pretty normal.


Thanks- Matt

matt could you inform me the model of your kubota?

[teneicm]

The engines are Kubota VE2203, 45 hp, marinized by Phasor marine. About 700 hours on it to date.

[GRIT]

If the smoke is brown (black) it is fuel that didn't burn in the cylinder.
It's common at startup, (but not as common with engines that have only 700 hours on them) and not usually a sign of anything nefarious.
Oil smoke is blue, water is white, fuel is black (but can look brown).

A quick test: run the boat on one engine (once it's warmed up) at full throttle for 5 minutes and note the maximum rpm, maximum boat speed, and amount of smoke from the exhaust. Do the same with the other engine (doing the same route, and same direction). If the speeds are similar and the smoke is similar, then don't sweat it.

Don't go out of the marina on one engine and back on the other unless you know there's no current, no wind and no waves, or you'll get different results.


As a rule, unless you have a dramatic event (sucking water into the engine), or filling the tanks with something other than diesel fuel, your engines will last for thousands of hours.

Cheers.
Paul.

[boatpoker]

I once changed my oil and on startup got a huge cloud of very definely brown smoke.
After many days of investigation it turned out I had a bad batch of Rotella. All the factory additives had settled into a sludge in the bottom of the container. Changed the oil again .... no more problems.

[teneicm]

Thanks all for the info and advice. We'll just keep an eye on it and see what happens....