View Full Version : False Temp. reading??

05-13-2004, 08:32 AM
Good day,
With my previous engine in my TR7, the Temp. guage always read close to hot. With my new engine installed, new waterpump, and new thermostat, the guage still reads hot. I have not had a problem with overheating though, the car is running fantastic.
Question is... what is the best way to check why the guage is reading so high?
Another hot sunny day here in Ontario... more TR fun. graemlins/driving.gif images/icons/grin.gif

05-13-2004, 09:36 AM
Easy. Take the gauge out and put it in a pot of hot water along with a candy thermometer or something to which you can compare the temp readings. Bring the water up to a boil and note the temp. Water boils at approx 212 F at sea level, both thermometers should be approximately the same.

If your gauge doesn't correlate to the other thermometer, your gauge may be out of whack. Not uncommon with these old Smiths gauges.

BTW, do this exercise when your wife or S.O. is out of the house. They get antsy when you mess with THEIR tools!

Good luck!

05-13-2004, 09:38 AM
I should probably add to not put the entire gauge in the pot, just the sending unit.

I hope this helps!

05-13-2004, 12:09 PM
The temperature sending gauge on a TR7 is $7 and changed in about 5 mins. It's a very common part that you may find even at NAPA. Before you mess up your partner's kitchen, I'd swap it out.

Exactly the same thing happened to me. I had visions of head gaskets and water pumps. It was great that, for once, the fix was something simple.

05-13-2004, 01:31 PM
Not sure if the 7 has a voltage stabilizer, but most cars do. If that goes south it can cause both the tempm gauge & fuel gauge to read eratically. Get a cooking thermometer that goes to 300 deg & let it sit in your rad when car warms up before you go pulling the sender, etc.

05-13-2004, 05:26 PM
Aloha KLUTZ,

My TR3 was converted from the original temperature gauge (remote reading thermometer) to a TR4 electric gauge. As Gary pointed out, this gauge needs a voltage stabilizer to read correctly. I don't know if this is the case with a TR7 gauge. In my case, without the stabilizer, water temperature varied gratly with engine RPM. When driving at highway speeds, 3000 RPM it would read very hot, but at idle it would drop rapidly to cold. After I installed the voltage stabilizer to the circuit, I got accurate readings.

Safety Fast,