To: flyrotary@lancaironline.net
Subject: [FlyRotary] Re: Cooling Problem
Reply-To: rogersda@myway.com
From: "Dale R." <rogersda@myway.com>
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Message-Id: <20040408145217.4FEDE12D4F@mprdmxin.myway.com>
Date: Thu,  8 Apr 2004 10:52:17 -0400 (EDT)


- On Thu 04/08, Al Gietzen < ALVentures@cox.net > wrote:
>No.  Less back pressure equals flow.  It’s the law for centrifugal pumps.  The only benefit to putting flow restriction at the thermostat is to increase the coolant pressure in the engine.  If you are running at speeds greater than say, 6500 RPM it may (depending on other things) reduce the risk of pump cavitation.
>
>It would seem there are only about two possibilities; air trapped in the pump housing, or incorrect flow path resulting in flow recirculating in the engine.  But then, you sems to have worked those.
>

   David, 
   There is another, albeit somewhat remote, possibility.  How's the 
clearance between the impeller and the pump housing?  More than about 
.020-.030" might be allowing the coolant to circulate between the
ends of the impeller and the center - especially if there is significant backpressure.  Also, are you absolutely certain that the 
impeller is firmly pinned to the pump shaft?  I've seen cases where the fit was tight enough that it wouldn't turn with moderate hand 
pressure, but the pin had been sheared off, and wouldn't spin at 
shaft speed.  (It won't do that for very long, though.)

Dale R.
COZY MkIV-R #1254

07:50


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