weird temp gauge problem. please help.

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e30geezer
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Post Sat Dec 10, 2005 7:37 pm

as above when i start the car from freezing cold the temp gauge hits the red in a few short minuites , she is not overheating. the gauge moves up and down erraticlly, seem like an elec fault any suggestions what to test or how to fix would be great thanks.
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michael24m
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Post Sat Dec 10, 2005 8:48 pm

it might be one of these:
the SI batteries need replacing, must remove the dash, and solder new ones into place.

or as i seen it on a previous post here, there might be a connector problem, seems that there are 3 contacts on the temp gauge, the two electrical leads, and one from the screw. i don't really remeber this, but ask Brianmooore he's very good with electrics.
in that post as i remember it, one of the leads from the temp gauge drags the needle into blue or red, not sure about it though.
e30geezer
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Location: london

Post Sat Dec 10, 2005 9:04 pm

michael24m wrote:it might be one of these:
the SI batteries need replacing, must remove the dash, and solder new ones into place.

or as i seen it on a previous post here, there might be a connector problem, seems that there are 3 contacts on the temp gauge, the two electrical leads, and one from the screw. i don't really remeber this, but ask Brianmooore he's very good with electrics.
in that post as i remember it, one of the leads from the temp gauge drags the needle into blue or red, not sure about it though.
cheers mate.
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Brianmoooore
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Post Sun Dec 11, 2005 11:38 am

First thing - you're sure it's not overheating? Haven't drained the coolant at all? (Can airlock in the heater circuit, and put the gauge into the red in a couple of minutes). Or a sticking thermostat?
SI board batteries make the gauge missread a bit, as do a loose nut on the back of the cluster (small brass nut right behind the temp gauge),but I've never seen either make it go right into the red.
Temp gauge signal goes through the C101 engine loom plug and socket on the bulkhead and on 6 cylinder cars (You don't say what yours is), through a 6 pin round plug and socket on a bracket under the inlet manifold, but problems with either of these would make the gauge under read rather than over read.
Apossibility is an intermittant short to earthof the wire from the sensor to the gauge, but there are no known weak points.
Try unplugging the connector from the brown temp sensor on the engine to see if this kills the gauge completely.