Join Date: Mar 2007
Location: New England
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Heads Up w/Impellers on Yanmar
Thought I'd pass along a potential info tidbit that I learned while sailing on my cousins boat a a few days back.
We motoring up to Annapolis because of the lack of wind and all of a sudden the motor stopped producing exhaust water and the exhaust went black. Emergnecy shutdown and then we went below to acertain the problem, while the wives rolled out the jib and saied the boat.
Sea strainer had some weeds in it so we cleaned it out, but we didn't think it was much. We restarted the motor and waited 30 seconds and no water. Shutdown the motor and checked the impeller. Everything looked fine, so I thought it was the muffler or mix elbow that was clogged.
To make a long story short, the impeller was actually shot. Although it had all of the vanes and looked good, the metal bushing had sheared away from the rubber so that while the impeller shaft was turning, the actual impeller was not. I would have never thought of this, but my cousin got the local Yanmar guy on the line and said what often happens is that sea water flow stops and without it the lubrication to the impeller vanes stops. Once the lubrication stops, it doesn't take much for the rubber piece to shear away from the shaft bushing. So while it looks fine, it is not. Even a small or momentary interruption to the coolant water flow can casue this according to the Yanmar rep.
Something to think about if you motor stops "peeing" out the back for any period of time.