Re: Force cooling system

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Posted by Ken Denman ( on May 29, 2005 at 20:16:26:

In Reply to: Force cooling system posted by Bill on May 29, 2005 at 19:38:15:

The holes in the motor tower are exhaust relief valves. They are there to compensate for the fact that at low revs, the motor may not generate enough exhaust pressure to force exhaust out through the prop hub. If the holes weren't there, the motor would be very hard to start and probably wouldn't idle very well.

To make a long story short, water comes out the exhaust relief holes not because the holes are water exits, but because the water is mixing with the exhaust as it falls down the tower. So, the amount of water that is coming out the holes is not a good guage of the health of the impeller.

It's a good idea to change the impeller every 3-5 years.

To make a short story long, using ear muffs is not a good indicator of the health of the impeller. Since the water is pushed into the water intake, it is circulated by the hose pressure, not by the impeller pressure. I.e. you could have lost all blades on the impeller and the motor would still cool properly with the muffs.

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