Exhaust smoke after winter lay-up - how long?

[Derek Rowell]

I'm in the process of purchasing a boat with a 55hp Yanmar that has apparently had very light use and low hours (according to the broker - no hour meter - he estimates 450 hours on a 1985 engine). Sea trials are not practicable, so the broker had the engine started on land with a recirculating coolant system. The boat had been sitting all winter.  The engine started right up and ran very smoothly - but with a LOT of smoke (I couldn't decide if it was black, blue or white - I would say dirty whitish blue . The amount of smoke diminished a bit over the 20 minutes of the test but it was still significant at the end. The engine was at idle with no load for the duration of the test. The cooling system was working fine. I could see no trace of fuel in the circulating coolant.  The broker and mechanic (and my surveyor) were not concerned. The mechanic said it was because the engine was not up to temperature at idle, and that as soon as some load was put on the engine the problem would disappear. But he works for the broker...  I have been around sailboats for a long time. I have never seen so much smoke from a sailboat diesel. My current Yanmar (22hp) will only show exhaust smoke for about 30 seconds at idle on start-up each spring.  Is twenty minutes of smoke too long? I am concerned that this indicates a severe compression problem.  Derek

 

[Dick Carey]

Yanmar Warm Up & Smoke

Derek,I beleive that the Yanmar should be up to normal operating temp in less than 20 minutes, or certainly by then.The Mixing Elbow (where engine exhaust and engine cooling sea water mix and from there go out as a 'wet exhaust') can soot up in 7 to 10 years. If it's never been changed (or not changed in the last 7 to 10 years), then it probably has built up soot inside it which creates a back pressure, which in turn causes inefficient burn of fuel, thus smoke (usually black smoke). Mine was smoking after 10 years and I had it replaced - a big difference. No more black smoke & a 30% increase in fuel efficiency.Also 450 hours sounds low for 16 seasons, unless it has had very little use.Good luck. Maybe you should talk to a diesel mechanic of your chosing.Dick CareyS/V Puffin1990 H-33.51W/ 2GM20(f) Yanmar.

 

[Steve Dion]

I have them put $2500 in an escrow account

Derek:I have them put $2500-4000 in an escrow account pending getting the boat launched. If there is nothing wrong with the engine the buyer gets his money. If you have problems this will probably take care of the repair.

 

[Chris Hyland]

Too much smoke

Derek, That sounds like a lot of smoke. How old was the fuel in the tank? Sometimes when the fuel has a lot of addditves such as stabilizers(winter storage) it will burn crappy and smoke.I do like the escrow option. It seems to be fair to everybody.Regards,Chris

 

[Larry]

Bail ... smoke may be bad omen...

Who wants to start with problems.Problems usually start building with time, so why start a new ownership with a load.I owned a Yanmar diesel tractor once that had a simular problem. New rings solved the problem, but we found it a new home real quick.Your experience with the 22 hp Yanmar is your most valuable "expert opinion".

 

[Larry]

Starter fluid can do Yanmar in...

I wanted to add , that my Yanmar tractor did fine until someone started it using starter fluid.I think that "sledge-hammer force" of the starter fluid on the cylinder head was what damaged the rings....