smoke from air intake -help!

[Petr]

Hi all
I have new 1gm10 Yanmar engine with about 10 hours on it and it started doing strange things .First - starting is a problem.It takes 3-5 times to fire engine.Second- once it started ,smoke goes out from air intake and the engine choked and stopped. I took apart exhoust system and all is clean, no holes in rubber pipes. When the engine on it's nomal behavior it works just fine! Any idea why this smoke shows up? I'm really confused.

[Ray Garcia]

Yes, small diesel motors can start in reverse where the the intake pipe becomes the exhaust and the exhaust becomes the intake. Not good for the motor and you should shut it down immediately. There may not be any oil pressure generated by the pump and the water pump vanes may become damaged from running in reverse.

Start by checking the oil level in the motor. Too much oil may be causing the problem. Next the starter, do you hear is spinning slowly? Make sure the battery is charged to capacity. Next I would advise you increase the throttle a tick before you engage the started. Finally the motor may have a timing issue that may need to be looked at by a mechanic.

Hope this helps.

[Petr]

I called in the Yanmar mechanic. he's pretty bewildered by what happened. of course, the engine started up perfectly for him when he was here! No back smoke. He's going to talk to some other mechanics and try to figure out what's going on. But thanks for your suggestions.