Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Posting-Version: version B 2.10.1 6/24/83; site biomed.UUCP
Path: utzoo!watmath!clyde!burl!ulysses!allegra!princeton!astrovax!biomed!lagasse
From: lagasse@biomed.UUCP (Robert C. Lagasse)
Newsgroups: net.rec.boat
Subject: Outboard water pressure
Message-ID: <53@biomed.UUCP>
Date: Thu, 16-May-85 17:49:33 EDT
Article-I.D.: biomed.53
Posted: Thu May 16 17:49:33 1985
Date-Received: Fri, 17-May-85 05:22:53 EDT
Organization: Mass. Gen. Hosp. - Dept. Biomed. Engineering
Lines: 21

Outboard engines use a rubber impeller as a cooling water pump and from what
I have been told by several outboard mechanics is that this part will burn
up and turn into little rubber bands in seconds if the engine is not
immersed in water while running.  Once this part fails, the engine will
overheat and (probably several minutes later) set off the high temperature
"hot" horn (which only the larger engines are equipped with) indicating that
the pistons have or are about to seize.  You are supposed to keep an eye on
the little "water indicator" hole that pisses into the water while the
engine is running assuring you that the rubber impeller is still turning O.K.
  OMC (Johnson/Evinrude) sells a water pressure gage which mounts on the
dashboard and comes "with tubing" so I suppose you have to run a hose from
the engine to the gage.  Still, you have to keep an eye on the gage.
  I have installed a fluid pressure switch at the engine by cutting the hose
that runs to the "water indicator" and inserting a tee connector to feed the
switch.  A pair of wires run up to the dashboard where a piezo buzzer is
mounted.  The buzzer sounds for a few seconds on start-up until the water
pressure rises which clicks the switch contacts open.  The power is tapped
from the "ignition on" + lead so all is quiet when the key is off.  This
also lets me know when I have left the key on without the engine running.
Any comments ??????
Bob Lagasse Biomed Eng. MGH