Suzie Too - Generator Tips

Suzie Too - Western Caribbean
David & Suzanne Chappell
Tue 29 Nov 2011 22:03
Our Moody had a Fischer Panda generator that was mounted on a frame above the engine and meant the impeller had to work hard to lift the water up 0.5 metre above sea level and running at 3,000rpm it needed frequent changing. The really annoying thing was that when the impeller started to lose blades they ended up in the heat exchanger – what sort of design is that – but all generators seem to be the same.
So on this boat I implemented the plan that I had already contemplated for the Fisher Panda – put a strainer in the output side of the impeller to catch any blades. Even though this Onan runs half speed at 1,500rpm and is mounted on the water line I still seem to change the impeller every 250 hours – so about twice a year. This Onan also has a “no raw water” cut out, but the blades still ended up – yep you guessed it in the bloody heat exchanger. It is a bit easier to get to on this unit, but it’s not the point.
So I did 2 things
1) Change the stupid raw water drain plug – which pisses sea water everywhere - for an elbow and fitted a drain hose – just like they do for the oil drain. I used 8mm fuel hose, as it can stand up to oil, diesel and engine temperatures.  Now when I change the impeller I just shut off the sea cock, open the raw water inlet strainer, to allow air through and drain the raw water before undoing the impeller housing.
2) Fitted a raw water strainer in the output side of the impeller pump. Fortunately the housing on this Onan is huge, so I had plenty of room. I ordered a spare hose from Cummins just in case it all went wrong and managed to find a strainer with a bracket that I modified to fit to the engine mount to support the extra weight and vibration. The impeller is mounted on a drive shaft at the end of the fuel injection pump, so quite easy to gain access. It took me half a day, but unbelievably it all worked and didn’t leak –  Ooops - I shouldn’t have said that.
While I was on a roll I also changed fuel filter and the anode again, which had done about 200 hours and was half eaten away, so the whole procedure took me almost a full day, but a great result and makes maintenance much easier in the future.