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BF50A water pump noise

P

pcaker

New member
Just had my water pump totally rebuilt professionally, including pump body, because old one failed after engine rebuild and showed signs of over-heating when taken apart. I have never run OB without water, and I doubt that marine shop did either. I check tell-tale every 5 minutes during use. On the few occasions over 11 years when it has ceased, problem has always been blockage at tell-tale nozzle. However, I have only gone 3 hours at moderate speed on rebuilt engine and pump, and yet pump sounds like it is failing. Tell-tale jet was strong after rebuild and throughout the 3 hour run. Only thing I can think of is a partial water intake blockage. Not enough to stop water circulating well around engine block, but sufficient to reduce water flow through pump so that it overheats.
 
I`d suggest that you check that your thermostat is working correctly as it sounds like that could well be the cause of your overheating and reduced water flow.

Cheers, Matt
 
Thanks Matt. Thermostat is brand new. Pre re-build overheating symptons were only inside pump. Noise may be coming from above pump.
 
Mechanic found that timing belt was a little too tight, and that was causing a light squeal at certain engine speeds - now cured. Funnily enough when I first heard noise I thought it was probably a new timing belt needing to bed in and polish a bit. But after 3 hours running, I somehow convinced myself sound was coming from lower down leg, hence my water pump concern. The way sound propagates through an engine can sometimes be deceiving.
 
Another sound to listen for on your 50 is loud whining coming from the flywheel area. The pitch of the whining increases with the rpms of the engine. On the older models with some time on them....the magnets start coming apart and lightly scrape against the exciter and charge coils. If you let them go too long, the flywheel may lock up. Looking at the magnets, you almost have to look at them with a magnifying glass and it is hard to believe that sure a small split could cause an issue.

Mike
 
Thanks Mike. I did ask mechanic to check that everything under flywheel was tight, when he replaced belt. Not sure if he would have detected what you describe, but I have noted it for future.
 
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