Flathead water temp sender

I need two new water temp senders for a flathead 8, The repops are 50 bucks a piece, has anybody used anything else that worked, and cost less. I using a 12 volt system by the way. Thanks. Dave

 

The Ford temp senders/gauges are using Bimetal for the function.
So its hard to get something else without replacing all parts.

id say Get new sender and gauge. Or original senders,
One thing the sender with two prongs, have only an on and off function.
So its not really necessery to use that one,

 

i used to SW gauges i got from somewhere. i cant remember where but they work well and i can see what the temp is on each side of the motor.

 

Mr 42, Thanks, I have both the single prong and the two prong, I can get resistance on the single prong but not the two prong, I assumed the two prong, and it's location in the pass side head was for the temp of that head, so the question is, could that sender be working since you say it is an on/off sender and be the reason I don't get any resistance with my meter?

 

And you used the senders for those two guages? just a set of wires to each guage?

 

A unique feature with the flathead Ford V8 is that there are two cooling systems, and unless you monitor each half, you may not be able to detect a serious problem. You are best to use the stock senders (the left and right ARE different, as previously noted-the right single-contact is a sender, the left is a 206-212 F switch)) with the stock gauge, or two aftermarket senders with either one switched, or two matching gauges. A factory Ford voltage regulator/reducer used from '56 for many years will drop the 12V to 6V if you stay with the stock senders and gauge.
Bob

 

Thanks Bob, The motor that the senders came out of had the two prong in the right/passenger side, that is wrong? I am familar with the reducer in question, there is a semi current thread that addresses it. Please excuse me as sometimes I can be "electrically challenged", I would like to keep the stock gauges, hence the reducer, but I'm at a loss as to the correct way to wire the senders, any help would be appreciated. Dave

 

Dave, as per my previous post, the single contact "sender" goes in the right passenger-side head; the two-prong switch unit goes in the left driver's-side head. They could be swapped, but Ford probably had them orientated so the single feed wire would come of the left side to run with all the other wiring on the driver's side.

Any flathead shop manual will show the electrical diagram of the temperature system, but basically, the right sender controlls the normal operation of the gauge with voltage through the nomally-closed left side temp switch. However, if the left side reaches over 206-212 F, the switch opens and sends the gauge full hot, just like when the ignition is off. Kind of a neat way to monitor both sides of the engine with one gauge. Did I "splain" OK?
Bob

 

Perfectly! and a Big THANK YOU! Bob

 

Here's a print.



Here's a link to all the dash gauge prints I posted a while back

http://www.jalopyjournal.com/forum/showthread.php?t=438925

Jim

 

What size threads are the sending unit?

 

The reproduction sending units have proven to be problematic. Just for fun, I took a malfunctioning stock unit apart and was able to fix it. Here is the thread : https://www.fordbarn.com/forum/showthread.php?t=226078&highlight=temperature

 

What size are the threads on the sending unit?

 

3/8" NPT.

 

Thank you.

Do you know what thread the port on the head is?
It looks like a straight thread.

 

Casey,
Wouldn't the head thread be similar to the sending unit?

 

My suggestion.....find two original senders. I use two, one for each bank and two gauges. They work just fine and I have not seen a difference of temps on either side. I'm happy!

 

Not always. Sometimes a pipe thread is designed to thread into a UNC or NPSM thread to seal. I don't think they do it very often , but I've seen it a bunch of times on blueprints in my machining career.

 

I know I'm kinda late getting in on this thread but, I am installing Stewart Warner's two gauge set that have have three gauges in each one. My question is on the temperature gauge. Can I run the open or closed sender on the drivers side of my flathead with the sender that comes with the gauges on the passenger side? I sent a message to Stewart Warner and haven't heard back from them. I hope I made my question understandable.

 

You can't tie the two together, you'd have to wire in a toggle switch so that you can send the signal from one side to the gauge, and then switch to the input from the other side. Or use two temp gauges.

 

Thank you