Message-ID: <3F86BD31.7090604@earthlink.net>
Date: Fri, 10 Oct 2003 07:07:45 -0700
From: Dale Smith <timepilot@earthlink.net>
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To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] Re: EWP - Success at last?
References: <list-2631016@logan.com>
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Jim Brewer wrote:

> I think the failure mode of the mechanical water pump is a soft 
> failure----starts leaking out the weep hole, loud noise from the 
> bearing or seal failing signals most people that something is wrong 
> with the car. Slow loss of coolant is also another signal, especially 
> with the idiot light telling you about low coolant levels. People have 
> many clues before pump fails.
>
> I am in the computer business and when the fan (air pump) stops 
> cooling the CPU you have a warning but if not quickly heeded the 
> processor soon fails. I think the failure mode of an electric motor 
> will give less warning than the mechanical pump will. I write this 
> based on my experience of changing about five water pumps on my 1993 
> Jeep Grand Cherokee 4.0 Liter engine with 358K miles. Perhaps this is 
> why the manufacturers haven't replaced mechanical pumps with electric 
> ones.
>
>  
>
> Jim Brewer
>

Should it prove feasible, a possible advantage of the EWP that has not 
been mentioned so far is the ability to plumb two in parallel (with 
appropriate check valves) for redundancy.  Auto makers have no burning 
desire to let you switch pumps and continue driving.

Dale Smith