Water Temp Gauge - Immediately Pegs Needle

[sdaughtry]

Today I freaked when I saw the temp gauge was absolutely pegged off the charts when driving home.. the oil pressure was fine and the car ran normal so I pulled over, checked for leaks (none) and drove home. Let car cool down completely (4 hours), popped radiator cap (full), checked oil (fine), so I restarted the car (started immediately) - gauge again went from normal (dead cold) to immediately pegging off the charts.

Never did this before today - I'm thinking it is the Water Temperature Sending Unit but want to ask the question before I get the part in from MSA.. anyone else run into this problem before? My '73 has the original gauges and I will assume has the original sending unit...

[Nissanman]

Mmmmmmm, methinks the sender is KAPUT!

To test: -

A] Disconnect the wire from the sender, gauge should not register at all.

If so, gauge good.

If not, gauge wire is earthing somewhere.

B] Earth wire for sender, gauge should max out.

If so, gauge good.

C] Reconnect wire to sender.

If the gauge still reads max. then the sender has developed an earth fault and is NBG.

You could confirm that by reading the resistance of the sender with an Ohm meter to earth.

That is my story anyway:D

[RogerZ]

earthing is limey talk for grounding. Lucas Prince of Darkness had some problems with that.