Hi All,

I have a temp gauge in a 56 f100 that isnt working. I am not sure if it is the actual gauge or the sending unit for it. What is the best way to check for either? Also, Where do i find the sending portion for the temp to check/replace? I thought it may be easier to replace that first and see b4 pulling the gauge out.

Thanks,

 

OK, this is not what you wanted to hear but because you don’t have 25 posts yet (dumb rule) you can’t use the search feature (I think) so go to Google advanced search with FTE forum as the web site and search for “temp gauge” you get all the answers you will need plus some.

 

In 1956 Ford trucks changed from 6 volt to 12 volt. Ford made the gauges and senders 12 volt. In 1957 Ford changed the gauges back to 6 volt and used a "constant voltage regulator" (CVR) in the power supply to the gauges. 6 volt gauges and CVRs continued to be used into the late 70's. What this means is the 56 gauges and senders are unique to 56 and do not interchange with earlier or later years and it can be hard to find correct replacements. You might try a phone call to Mid Fifty F-100 Parts.

You can bench test a 56 gauge by hooking it up to two flashlight batteries in series (3 volts) and it should go to mid scale.

 

Easiest way to test you system is to find the temp gauge sender on your engine (it will look a little like a small brass spark plug sticking up and will have a wire attached to it. It's probably on the intake manifold, but not 100% sure on a 56.

After you have found it, with the ignition "OFF", disconnect the wire from the sender and set it some place it isn't touching anything.

Get a helper to read the gauge. Turn the ignition "ON" and touch the end of the wire you removed from the sender to a good ground on your engine block or head. Ask the helper if the temp gauge moves at all toward "C" (it should normally park on "H" when the truck is off).

If the needle moves when you touch the wire, then the sender is bad.

If it doesn't move, get a meter or circuit tester and test to see if the gauge is getting 12 volt power.

Power comes in from the "ACC" terminal of the ignition switch when the key is turner "ON".

With your meter or circuit tester leads, touch one of the studs (with the wires on them) on the back of the gauge and the other lead to ground (like the dash). If you have power going to the gauge and it didn't move when you grounded the wire to the block, the gauge is bad OR the wire from the gauge to the sending unit is bad.

If you don't have 12 volt power at the gauge at all, then your wiring from, or your ignition switch itself, is bad (but I'm assuming your gas gauge is working so there must be 12 volt power coming out of the ignition switch).

This must all be done while standing on your left foot only.

 

Thanks everyone, this is all a great help to me.

Question - when you purchase a replacement gauge from places like Blue Oval the come with the sending unit, with these set ups work or does it all have to be OG parts (no repops)?

Julie - thanks for the step by step, that really will come in handy this weekend when i try this.

thanks,

Rusty

 

When you buy a replacement gauge, and it comes with a sender, it will work as long as it's the correct voltage (6 or 12 volt). As a matter of fact it's absolutely critical that the sending unit be "madefor/matched to" the gauge.

C&G Ford parts sells the 56 Temp Gauge sender for $55. https://secure435.hostgator.com/~dlv...=107&t=785&tn=

Take a look, it has a picture of the sender if you need to know what you are looking for (the long brass tube is inserted into the engine and threaded in)

Give us an update when you find out anything.

Seems to be the summer for temp gauges!

 

Thanks Julie, You have been a HUGE help. So just to clarify the sender you mentioned would work with the stock gauge, or is it better to get a replacement gauge/sender at the same time?


thanks again, will for sure update the post.....

Rusty

 

As was mentioned, you should get a matched pair, if you are unsure what you have. 1956 was the first year for 12 volt (Ford) and the last year for descending voltage--the gauge needle goes to the right when it is off. In 1957, gauges were changed to ascending voltage--the needle starts at the left and moves to the right when power is applied..

 

If you have a stock 56 gauge, then the sender in the link I posted is made for that gauge. If your gauge is working, just buying the sender (the one made for the 56 gauge) is sufficient.