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Re: Hot or not?

To: Spitfires@Autox.Team.Net
Subject: Re: Hot or not?
From: "John T. Blair" <jblair@exis.net>
Date: Thu, 19 Nov 1998 19:14:34 -0500
At 06:07 PM 11/19/98 EST, you wrote:

>When driving my Spit for the first time this summer, I kept pulling over to
>the side of the road whenever the temperature gauge reached its max, which
was
>roughly every 5 minutes. I couldn't figure out the problem, b/c it was
full of
>coolant and oil, and everything seemed to be in order. I decided to test the
>sending unit, so I boiled some water and poured it into a thermos and stuck a
>thermometer and the sending unit in it. The thermometer read 170 degrees, i
>believe, and the sending unit was at its max again. I assumed the sending
unit
>was bad. However, I bought a new one and the problem is still there. In the
>winter, this rarely occurs, but it still reads b/w 3/4 and max all the
time. I
>imagine in the summer it will be hotter. Is this normal? I would like to
know,
>b/c it is extremely frustrating, and I dont want to inadvertantly run my
>engine hot for too long. 

KRis,
 
  You were on the right track checking the temp guage & sending unit with
the boiling water.  If the guage doesn't match the thermometer, then there's
something wrong with the guage system.  Assuming it is a late model car
with electric guages, the guage system consists of Power from the battery,
a regulator (usually 10V - a little rectangular thing normally screwed to
the back of the Speedometer), a sending unit and a guage.

You can test the sending unit by itsself.  They are usually heat sensative
resistors.  So attach an ohm meter across the sending unit (if only a
single connector, then one lead to that, the other lead to the sending units
case).  Measure the resistance.  Then put it in some hot water, but NOT
boiling.  Did the resistance change?  Finally put it in boiling water, did
the resistance change?  If yes then the sending unit is probably fine.

Also check every electrical connection in the Temp guage system.  Make sure
all connections are clean and tight.

A quicker test, is to find someone else with a similar car, and swap sending
units, then guages.  

Hope this helps.

John.

>
>
John T. Blair  WA4OHZ          email:  jblair@exis.net
Va. Beach, Va                  Phone:  (757) 495-8229

              48 TR1800    65 Morgan 4/4 Series V
71 Saab Sonett III     75 Bricklin SV1     77 Spitfire

www.team.net/www/morgan        bricklin.shel.olsy-na.com/bi



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