no power

[Tim Op't Holt]

My boat is powered with a Yanmar 2GMF. After changing the thermostat this weekend, I decided to motor out of the slip. After a typical start and idle out in reverse, I went into forward and throttled up. Instead of the usual forward momentum, the engine hesitated, blew out some black smoke, and failed to do much more than idle speed. It nearly stalled. I limped back into the slip and let the engine idle. When throttling up in idle, I saw more than the usual white smoke. I did not attempt another trial under load. I suspect clogged filters. My approach to this will be to first replace the engine and tank filters, top off the tank, and add some fuel algicide. The tank had been run-out a little over a year ago, so the oldest fuel is that old and I had added some fungicide at that time. Coments?

 

[J McCue]

black smoke

You say you changed your filters- I assume those are the air and fuel filters. Since you don't seem to have a problem at idle, could it be that you are not getting enough water thru the cooling system to keep the engine temp down. A clogged intake may allow you to run a while in idle , but when you hit the throttle you are choking the engine. A hot engine causes very "thin" air in the cyl. and more diesel will just drown it - so you have black smoke.I had similar problem while circling waiting for a ICW bridge to open. When I went to throttle up to get thru the bridge, I got a big puff of black smoke and the engine went dead. I coasted thru the bridge opening and anchored on the other side. Found that the eel grass (which gets chopped up by the motor boats) had collected at the bidge isthmus and in circiling I had sucked it into the strainer and eventually resricted my raw water coolant flowthru. Jim McCue

 

[Steve Dion]

Color of smoke.

Tim:The color of the smoke usually indicates the type of problem that you are having.White smoke is usually overheating (steam)Blue smoke is oil burning.Black smoke is fuel.Why did you change your thermostat?If the engine was running warm, it may have been really a problem with the elbow or a clogged intake. If the elbow is the problem you end up with too much back pressure in the exhaust and the fuel cannot burn properly.The engine can also run warm from a overload condition from a oversized prop, fouled prop etc.I would start by check the raw water flow from the thru hull to the elbow first.

 

[dan campbell]

air in your system

tim, you may have air in your system. If your 31 has a tall fill hose like my 28.5, it traps a lot of air when you are filling the system up with coolant. on my 28.5 i loosened the clamp at the bottom of the fill hose as i was pouring anti-freeze in it and i could hear the air being forced out. it also sounds like your overheat warning alarm may not be working.