Thursday, May 1, 2008

Temperature Gauge

Temperature Gauge Sending Unit

The temperature gauge for the 1955-1957 Thunderbird is located on the driver's side portion of the engine near the firewall. It is screwed into the top rear portion of the left side cylinder head. The sending unit is almost directly below the mounting bracket for the carburetor linkage. It looks similar to a spark plug with one wire attached to it and is clearly visible and easily accessible. The sending unit functions much like a thermometer. It does this by moving the needle on your temperature gauge as your car's coolant temperature rises. For those of you out there with "stuck" temperature gauges, this tip is for you.

To test your temperature gauge, simply disconnect the wire attached to the temperature gauge sending unit and touch it to any good ground. Your dash gauge needle should move. If it does, your temperature gauge is functioning properly and the problem is probably a faulty sending unit. If the gauge does not move at all then the problem is either a loose or cracked wire and/or a bad temperature gauge.

To remove a faulty sending unit it will be necessary to drain enough antifreeze out of the cooling system to leave your radiator about one-half full. This will lower the coolant level to a point lower than the sending unit. With enough anti-freeze drained from the system, you can safely remove the sending unit from the cylinder head without having anti-freeze leak all over your "detailed" engine compartment. Depending on what year Thunderbird you have, you will need a box wrench size 5/8" to 3/4" to unscrew the sending unit.

When installing the new sending unit, use teflon tape to help prevent any coolant leaks. With the engine running, pour the coolant back into the radiator very slowly. Don't pour all the coolant back in at once. Try to divide the amount you need to refill the radiator into four or five fillings. Allow a few minutes in between fillings to make sure the thermostat has opened and your coolant is circulating. Make sure your heater is turned to the "on" position. The blower does not need to be engaged, but the heater valve does need to be opened. By turning the heat "on" and pouring the anti-freeze back into the radiator very slowly, you will avoid developing any air pockets which may prevent your cooling system from functioning properly. Once the engine has heated up, check to see if your gauge is working. You should now be set to enjoy the summer: the sun, warm air, road construction, traffic jams, and temperature gauges warning you of impending disaster.


Anonymous said...

I was wondering - is there a different sending unit for the gauge -- and the idiot light ?? Someone said there was.. What say you ??

jlgrnbrg said...

There is only one temperature sending unit tied into the gauge on the dash. The only "idiot lights" are for the oil pressure and generator. The sending unit for the oil pressure switch is on the drivers side of the block about mid way front to back, under the exhaust manifold. Is this what you are referring to?

Thanks for your comment.
Joel for/CTCC9

edsel58 said...
This comment has been removed by the author.
edsel58 said...


I'm the new owner of a '56 'Bird. The temp gauge is at *H* with the ignition off. Is this normal, since any other gauge I've ever seen is at *C* when the ignition is off?

Thanks! Warren in CA

jlgrnbrg said...

I had the same question when I first bought my '55. Yes- the needle goes to the "H" when the ignition is off. As soon as you start the car, the needle goes to the "C" and rises as the engine warms up.
Hope this eases your mind about anything being wrong or miswired.

Thanks for your comment.
Joel for/CTCC9

edsel58 said...

Hi Joel,

Thanks for easing my worried mind and your quick response! I'm very familiar with '57-'59 full-size Fords, so this had me going for a little while.

Thanks again,

Unknown said...

The temperature gauge on my 56 TBird was working ok but
has suddenly stopped (stuck at "C"). Don't know if the following
might have any bearing, but I recently had to replace both the
Ram Cylinder and the Power Steering Control Valve. The
replacement of these was successful and corrected the
super-sensitive steering problem I was having. Don't recall
removing any wires at all, but will check the one you have