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MG MGA - Temp. gauge

Hi All.

My temperature gauge seems to have developed a strange behavior:
When driving around for about half an hour the gauge starts to move upwards, slowly but firmly it creeps all the way past the 230 mark and as long as it can go, and just sits there untill the engine is shut off. Then it falls rather quickly to about 190 and slowly back to 90 as the engine is cooling down.
With the engine idling and the gauge sitting at 230+ I have never seen the actual temperature above 190 when checking on the thermostat housing with an infrared gauge.
Any solution?

L. Christiansen

A half hour before the gauge starts moving seems a long time to me. Mine starts moving within a minute or so and after 5 or 6 minutes of idling the temperature stabilizes at around 160degF. This is around 20degC outside temperature; maybe it's a lot colder where you are?

Anyway it sounds as if you need to recalibrate your pointer as the gauge is reading high. You might be able to do this without removing the gauge from the car, I've always had the gauge out when I've needed to work on it. But first remove the capillary bulb from the engine and place it in boiling water to confirm the gauge needs calibrating.

Then loosen the gauge from the dashboard and remove the bezel by rotating it and also the glass. Remove the temperature pointer either with your fingernails or a special tool and with the bulb still in boiling water replace the pointer at 212degF.

If this doesn't correct the problem then the internal gauge mechanism needs inspecting............................Mike
Mike Moore

Sorry Mike
I did not explain the problem precisely.
I ment that the temperature guage rises fully normally as the engine is
reaching its oprating temperature at 160F to 170F and sits firmly there for about a half hours driving and from there begins to creap upwards. The ambient temperature is around 80F.
When I did the head 5 months ago I checked the gauge in boiling water and it was spot on.

L. Christiansen

This thread was discussed between 23/07/2016 and 24/07/2016

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