Corvair Forum

My cylinder head temp gauge does not work. According to the '65 wiring diagram there is a separate single wire connector which attaches to the wire from the thermister. The thermister wire is supposed to be white. Now I do have a single wire connector coming through the bulkhead but it is not plugged into anything. I do have a white wire which would seem to be the thermister wire since it has what looks like a high temperature jacket surrounding the wire.
This wire just loops back on itself - back to the main engine connector.
The white wire is connected to the two wire connector on one end and then into the main engine connector on the other.
2 questions:

1. What is this wire for ?

2. Where does the wire from the thermister physically connect to the wiring harness which goes back to the instrument panel ?

Alec

That braided wire is the ignition resistor wire. The thermistor wire does NOT enter the engine bay. If you look at the wiring diagrams the thermistor wire is a single plug pigtail off the rear end of the main body harness before it enters the engine bay. The wire from the thermistor is supposed to exit the left side front engine shroud and connect to this plug. Look up in the area of the starter.

terribleted wrote:That braided wire is the ignition resistor wire. The thermistor wire does NOT enter the engine bay. If you look at the wiring diagrams the thermistor wire is a single plug pigtail off the rear end of the main body harness before it enters the engine bay. The wire from the thermistor is supposed to exit the left side front engine shroud and connect to this plug. Look up in the area of the starter.

That's interesting. I didn't think the resistor wire came into the engine bay. I thought it came off the ignition switch back to the connector in the engine bay. Thanks for clarifying that.

Also, I appreciate the thermister info. I'll check on that since I did replace that starter early in my restoration. Maybe I just disconnected the thermister wire and failed to reconnect it !

Alec

Ted is correct - the ballast, or resistance wire, is always in the engine harness between the bulkhead connector and starter pigtail connector. From the stater pigtail connector to the starter, to the coil is all copper wire.

The ballast wire is a long wire to dissipate heat, therefore it's looped around in the engine harness.

If I remember correctly, only the 1962 Turbo Spyder Corvairs had a compact ballast ceramic block resistor.

So the thermistor wire does not run to the wiring harness at the dash? Do you have any pictures that show how it attaches to the starter? I have a Corsa dash in a '66 Monza with a 140. and I'm trying to figure out some of the various gauges. I would still need to run a wire to the gauge itself wouldn't I? I'm not the most electrically minded person I know.

The Corsa wiring harnesses for the engine, tunnel, fusebox (under dash) are different versus the Monza (and of course the instrument cluster has it's own wiring harness). You do have to add a wire for the thermistor to temp gauge, coil to tachometer, and the Corsa used two wires, one each for the oil pressure and overtemp switches at the engine. The separate oil/temp wires were only installed for a "buzzer" on the 65 Turbo Corsa and you don't need to add them (just use the single Monza wire).

Replacing all the harnesses is expensive. I usually replace the engine harness (typically worn out) and add the wiring to the tunnel and dash harneses. You have to add a wire(s) from the thermistor to temp. gauge and a wire from the coil to the tachometer. Consideration has to be made for removing the engine. I have the stock connector contacts and housings (Clark's sells them) and the proper crimp tools and know electrical. It's a fair amount of work involved in routing the wiring like stock. Most just run the wires haphazardly from the back to the front. For the unknowledgeable it's best to find someone in your area who knows how to do automotive wiring on old cars.

Hopefully these diagrams and illustrations will help. The single thermistor wire for the temperature gauge is routed through the front left heater duct sheet metal. All of the illustrations can be enlarged for better viewing by clicking on each diagram.

Brad,

Thanks for the diagrams. However I discovered why my temp gauge isn't working- some previous owner removed the thermistor from the cylinder head. I have the wire but no sender. I'll eventually look for an alternative but right now it's not on my radar. First priority - finish rebuilding the brake system, then rebuild the turbo which isn't working, then pull the engine to replace seals and bearings and install new pistons, rings, jugs and fix whatever else needs fixing while the engine is out. Then body work and paint. I may not need a temp gauge till next year !

A wise man told me it would be best to add 4-5 new wires. I installed 3 and then found out I needed more. So now I have run a total of 5 new wires from the back to the front. I zip tied them to the original harness and was able to attach to the harness for at least 90% of the way. I've crimped plug ends to the wires and they will be able to just be pulled off the terminals so when I drop the motor they won't be a problem Thanks for the information.