MkII Temperature Sender

From: John Broderick broderij@tcplink.nrel.gov
Date: Thu, 10 Aug 95 08:40:58 mdt
To: uunet!validgh.com!mr2-interest@uunet.uu.net
Subject: MKII temperature sender

I had the temp sender fail on my '91 Turbo also.  The sender
is located on the ENGINE END of the large upper coolant hose
that connects to the removable pressure/fill cap.  The
sender is mounted in the alloy thermostat housing on the
rear facing side of the housing, down low.  There are 2
senders and a switch mounted on the housing.  The guage
sender has one wire.

To diagnose this, put the car in neutral and set the
park brake.  Turn the ignition switch to the "on"
position with the engine off.  Look at the position of the
temp guage.  Remove the sender wire connector at the engine
end.  The gauge may drop lower, informing you that you have
the correct wire.  Ground the wire, using a paper clip, the
guage should read high.  If so, the guage is fine and sender
is bad.  If the guage does not move, the guage itself is
supect.

Here is a tip for replacing the sender:  To minimze coolant
loss, you can remove the cap, squeeze the large upper
coolant hose and replace the cap to create a "VACUUM" in the
cooling system.  You can now replace the the sender w/o have
to drain the cooling system.  The system should be bleed of
air after this procedure.  If you have a large amount of air
in the system the heater will not work, and the turbo will
not be cooled.

Good luck, John Broderick.