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cousindave
12-22-2010, 01:54 PM
My series III's temp gauge is reading in the red! I replaced the thermostat and sensor today and it still reads in the red. I'm wondering how do I know that it is not overheating? Is feeling the top hose enough(cold to the touch)? Thanks!
Terrys
12-22-2010, 02:39 PM
stick a thermometer in the radiator
stomper
12-22-2010, 02:41 PM
a candy thermometer in the top of the radiator? Infrared block temperature? Testing the temp sender with the thermostat out? The search feature has tons of knowledge on this.
SafeAirOne
12-22-2010, 02:49 PM
If you've put in THE CORRECT replacement temp sender, then what's the resistance, in ohms, between the terminal on the temp sender and a good ground when the engine is hot? Make sure you remove the wire from the sender.

The resistance value should be approximately 75 ohms when the coolant is 190 degrees and 90 ohms when the coolant is 180 degrees. Probably don't want to see too much less than 70 ohms here. If you have the correct sender and are getting readings in this range, either the wire between the gauge and the sender is grounded or there's an over-voltage condition in the system.

How many volts are at the temp sender wire (with the wire removed from the sender)?

This can be a little tricky with a digital voltmeter, but using an analog one, you should see an average of 10 volts. A digital will fluctuate between 12v and 0 volts. If it is pegged at 12v, I'd consider the voltage regulator shot.
cousindave
12-23-2010, 10:17 AM
SafeAirOne:
thanks. Seems my voltage regulator is shot.. voltage never drops below 12v
Terrys
12-23-2010, 10:39 AM
SafeAirOne:
thanks. Seems my voltage regulator is shot.. voltage never drops below 12v
Theres your high temp guage reading. It's mounted to the back of the multifunction gauge on a 2A, might be the same on an S3, can't recall. If you get stuck, I think I have a few. BTW, it will also affect your gas gauge reading.
SafeAirOne
12-23-2010, 12:04 PM
For a few bucks, I just built a solid-state voltage regulator and have no problems since. The thermal/mechanical regulators are guaranteed to fail eventually.

I didn't bother using the old stabilizer housing or the LED, but this is generally the way I built mine:
http://www.britishv8.org/Articles/MGB-Voltage-Stabilizer.htm