New member with temperature gauge question

[GGoodsell]

Hello, I'm a new member with a '67 MGBGT that I've owned for 11 years. I've done a rolling restoration and use the car regularly. Recently I barely get any temperature indicated on the gauge. It's worked perfectly before so I thought the thermostat might have failed in the open position. It's been replaced but the gauge still barely registers. I'm figuring that the gauge has probably failed. there is an oily area along the capillary tube next to the block so I figure a leak. Does anyone have any other suggestions?

 

[Steve_S]

The capillary tube is filled with gas, not liquid so the oily spot is most likely coming from something else. Check the gauge by removing the sensor from the block and immersing it in a pot of boiling water. Use a candy thermometer to check the actual temperature of the water. If the two don't match, it's probably a gauge problem.

I've heard of people simply inserting a thermometer into the radiator but I'm not sure if this is an accurate (or safe) way of doing it. Remember to drain the coolant before removing the sensor from the block!

 

[Guest]

Or use an infrared thermometer aimed at the thermostat housing to read the actual temp. Bet your locall radiator shop has one if you don't

 

[Guest]

Welcome to the forum. The guage on mine is electrical and is a device with a thermistor in it and a wire fastened to the sensor not a capilary tube. I think yours might be the same as this artical doesn't show anything different see --- https://www.mgcars.org.uk/electrical/temp.html
Since yours isn't reading much (and the temp of your engine is going to normal) then either the sensor is defective or the voltage getting to it isn't high enough. Read the artical on the web site for help.
Good troubleshooting,
Bob

 

[Steve_S]

Early cars had capilary tubes. Later ones were electronic.

 

[Guest]

OK, sorry, I stand corrected. My VB catalog says the 67 had an electric sensor and the Moss catalog says it started in '68.
Bob