1GM10 - White Smoke and Oil slick in the water

[Baroudeur]

Hi All,

I just had my 1GM replaced with a refurb 1GM10. It starts from cold instantly, and freely responds to throttle changes both in and out of gear.

However, it also smokes a lot at higher revs, a white/light grey smoke in very generous quantities, and also leaves black globules of what looks like oil in a sheen on the water from the exhaust.

From what I can find, some folks think fuel problem and some think oil problem. Some even think air intake problem!

Has anyone experienced similar? Or can give me a fairly reliable indicator of where to go first in trying to resolve the issue?

Thanks!

 

[peteK]

Could be a partially blocked exhaust elbow.

 

[Dan Tribe]

Do you know how thorough the refurb was?
My GM2 suffered the same problems and considered a refurb unit. As far as I could tell, they check if it starts then clean and spray paint it. It didn't seem like a good risk.
The problem with my old engine was a corroded cylinder head. Cheaper to buy a new engine than the spare part.

 

[Ferring]

Have you examined any of the globules?
A friend recently had similar output which was not oil but small particles of soot like carbon from partially burnt fuel. The diagnosis was over-fueling.

 

[Seamechanic]

Hi,

obviously a professional refurbished engine shouldn't show symptoms like that...
Oil in the exhaust could come from burnt through cylinderhead. These Yanmars are prone to have the exhaust elbow corroded in a way that cooling water reaches the cylinderhead instead of flowing down into the exhaust line. High temps in conjunction with (salty) water lead to holes from the exhaust port into the crankcase. If this happens oil can get into the exhaust. In the other direction water can ingress into the crankcase leading to white smoke/steam as it enters the air intake through the crankcase ventilation....
Unmount the exhaust elbow and check it's ok.

Frank

 

[Impaler]

I had exactly the same problem. It was a corroded cylinder head. My advice would be to take the head off and look for any holes that shouldn't be there.

 

[Baroudeur]

Thanks everyone, some good pointers here. The chap next to me in brighton had suggested I just leave it running at +- 3k revs, in gear, for an hour or so to fix the problem - sounded potentially even more expensive to me, but he was pretty adamant.

The refurb engine was from an official Yanmar marine dealer, on the South Coast so I felt the refurb would be a fairly good proposition.

I'll take a look at the oil, fuel and exhaust elbow on Thurs/Fri this week and report back any findings.