MGB: Diagnosis of temp gage problem

Have a 79 mgb, 90,000 miles...all of sudden the temperature gage stopped working. There has not been any history of overheating problems. How can I tell if its the gage or some wiring problem? Open to all suggestions..thanks, Keith

Try replacing the temperature sending unit. They seem to break pretty often.

Pat

If the fuel guage quit at the same time, it's the voltage regulator under the dash.

With the ignition key in the run position, take the wire off the temp sending unit on the side of the head. Short it to the engine block, If the guage goes all the way to the hot side, the problem is the sending unit. If not, check continuity on the wire to the guage. If good the guage is probably bad. .....

What is a good reading when shorting the temp sender to ground? My gauge reads between the N and hot all the time and I know the engine is running 180* as I've taken temp readings with a laser temp indicator.
Sorry to hijack the thread, same subject though!

Grounding it should peg the needle on the hot side.

Derek is correct. Don't hold the wire to ground longer than you need to. Few seconds is all that's required for the needle to full sweep. It doesn't jump across, just a steady climb.