MG-Cars.net

Welcome to our resource for MG Car Information.

Recommendations

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG MGB Technical - Damaged water temp gauge?

Hi all.

My '73 BGT overheated one year ago and the water temp gauge indication went over the end of the scale. That is entering the oil pressure zone!

Engine still ran after that and it was not a problem since I've rebuilt it completely. New radiator too.

Mechanically car is fine, but the water temp indication now rests on the N, instead of C. It works from there, but during normal driving stays on H.

It is probably damaged, but can I open it (front glass) and rotate the pointer clockwise by hand?? I know that probably the accuraccy is gone, but will it work?

Cheers,

Valter.

Valter

Valter,

Take the glass out by rotating the chrome bezel and then pulling.

The needle should be removable by pulling, use a small screwdriver under the shoulder, and then replace in the correct orientation. Watch you don't bend the spindle.

The flattened tube in the gauge that increases in dia. as the engine heats up has probably stretched slightly, mine did this when I left the earthing strap off on an engine rebuild and was using the gauge sender as an earth. Mine was off the scale cold!

You can do the above without removing the sender from the head. Just have the gauge hanging out of the dash.
I actually managed to take the whole gauge apart with it hanging out of the dash as the internal gears had come adrift as well.

The ideal situation would be to remove the gauge and test it in a pan with a thermometer so you know exactly what is happening. Didn't bother with mine and it now reads a bit low, but I know exactly where on the gauge it will boil (another story) and that's what's important.

Chris
Chris C

No need to move the needle ( you will probably damage it / the spindle in the process) just pull the pressure unit outwards gently to disengage the quadrant from the gear and rotate the needle in the required direction and release the pressure unit - you may need a few goes to get it right.

Test by heating a pan of water to 190 degrees F and checking that the thermometer reads N
Chris at Octarine Services

Chris (Octarine),

I didn't read your instructions last night, so I followed Chris C instructions.

I removed the chrome frame, then the glass and gasket. Needle was stuck so I just gave it a rather strong tug. Managed to take it out but I bent it. After straighting it I've installed it on the right position.

To check it I now must remove sensor from cylinder head and heat some water, right?

Another question: should I glue the chrome surrounding? It was glued before I can see that.

Thanks,

Valter.
Valter

Valter.

To check it you will need to remove the sensor from the head. I would tend to do that in your case as you now do not know exactly what the gauge scale corresponds to in temperature.

The chrome surround often loses its tags that lock it to the surround. That is probably why it was glued. Use a soft glue so you can get it off again.

Chris
Chris C

The same thing happened to my MGA sometime before I bought it. I found that the sensor was expanded and was a bit difficult to get out of the head. I removed the thermostat cover and was able to get behind it and help it out without putting undue stress on the tube.
R. L Carleen

This thread was discussed between 12/10/2004 and 13/10/2004

MG MGB Technical index

This thread is from the archive. The Live MG MGB Technical BBS is active now.