Temp Guage not working.

[JayBee]

I've got the same scenario. My temp gauge barely moves, never reaches the "normal" range. The motor is being rebuilt as we speak. Upon dismantling it, the shop found that my thermostat was permanently stuck open. He even asked me if the motor ever got up to operating temperature.

When I get the car back I'll let you know if the gauge is behaving any different. It has been broken in on his engine jig and there's a 180 degree TS in it, so I should have an update soon.

[ShelbyDogg]

I have a 440, A/C, 3 core 26" radiator with a shroud and clutch fan, 195 degree thermostat. I also have a second sending unit for my fuel injection computer.  On very hot days, the dash guage shows between the bottom cold line and bottom line of the operating area. This is normal because my computer display shows 202 degrees. The only ones here complaining about high temps, had a cooling problem or an over-bored engine block or cracked head.

Put a second gauge in, if you really want to test it to confirm your temp.   My temp gauge did rise with highway speeeds in '85. I had a clogged 2 core radiator that got replaced with a new 3 core.

[jauch]

It's normal for the temp. to increase for a short time after you shut off.  All the cold air rushing into the engine has a cooling effect on the inlet manifold etc. so it is cooler than the other parts when the engine is running.  After you shut off it all evens out and the inlet manifold temp. increases before it all finally cools down.

It's common for the senders to make the gauge read low.

If you want the gauge to read higher you can put a shunt resistor in parallel with the sender.  It looks like you need something about 80-100 ohms.  You can go here to work it out the easy way:

http://www.sengpielaudio.com/calculator-paralresist.htm

I though about that as well to get the gauge needle mid way at normal running temp, but isn't adding a resistor going to give me the opposite affect, don't i need less resistance to get the gauge to move toward mid way. unless my thinking is backwards

[ShelbyDogg]

, don't i need less resistance to get the gauge to move toward mid way. unless my thinking is backwards

Adding a resistor in parallel with another resistor give you less resistance.  Just like water flowing through 2 hoses.  Adding them in series (end to end) gives you more resistance.

[UKcuda]

What ^^ he said.

Based on your measurements the resistance value I suggested fitted in parallel should give you somewhere about mid-range on the gauge at normal temp. and full range at overheating type temps.

I've done it myself and it works    but bear in mind these stock gauges were only ever a rough guide at best.

[jauch]

What ^^ he said.

Based on your measurements the resistance value I suggested fitted in parallel should give you somewhere about mid-range on the gauge at normal temp. and full range at overheating type temps.

I've done it myself and it works    but bear in mind these stock gauges were only ever a rough guide at best.

Exactly where does the placement of the resisters go, between the wire and the sensor?

[UKcuda]

Exactly where does the placement of the resisters go, between the wire and the sensor?

No, that would be wired in series not in parallel.  It goes between the sensor wire and ground.  You can put it anywhere on the wire so you could connect it up behind the dash if you wanted it out of the way but for testing to check you have an appropriate value it's easier to connect it between the sensor terminal and the engine ground (obviously you need to leave the wire to the gauge connected as well).

[jauch]

No, that would be wired in series not in parallel.  It goes between the sensor wire and ground.  You can put it anywhere on the wire so you could connect it up behind the dash if you wanted it out of the way but for testing to check you have an appropriate value it's easier to connect it between the sensor terminal and the engine ground (obviously you need to leave the wire to the gauge connected as well).

thanks for all the help, now that makes since.... i was struggling to understand how placing it between the wire and the sensor was going to make a difference, thanks for the explanation.

-tim

[jauch]

50ohm resister in parallel worked like a champ, thanks again.

-tim

[UKcuda]

50ohm resister in parallel worked like a champ, thanks again.

-tim

  

Now you can enjoy that special feeling that only comes from seeing your original gauge needle sitting in the right place.