Temperture sending units

[R2W55]

My 40 V8 flathead has one temperature sending unit installed and the other hole is plugged with a bolt. My temperature gauge says I am running hot.
Do I need the other, 2 leaded sensor, for my gauge read correctly?
I was also considering installing a after market sensor and gauge to double check the temperature.

[Old Henry]

The two lead sensor is not needed for the single lead sensor to work right. The two lead sensor is just a "circuit breaker" that opens above a certain temperature to send the gauge to HOT. I have a mechanical sender for a mechanical gauge in that two lead sensor hole to know more precisely the true temperature of the engine.

[R2W55]

Thank you. Since I am thinking of adding a gauge set, do you know of any 6 Volt gauges (to monitor charging) in the same style? All I can find are 8-18 v models.

[Joe Immler]

R2 I agree with Henry. Install a Stewart Warner or similar brand mechanical gauge. You will know for sure what your temp is. I also installed an oil pressure gauge next to the temp. Amazing what the real pressure is vs: what the dash gauge says.

[Old Henry]

I use a cheap mechanical gauge from AutoZone. See this thread: https://www.fordbarn.com/forum/showthread.php?t=88541 I have also added a mechanical oil pressure gauge to monitor that more precisely.

[19Fordy]

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The temp sending unit thread is a pipe thread. I hope that "bolt" didn't mess it up.

[Viroid]

Originally Posted by Old Henry

I use a cheap mechanical gauge from AutoZone. See this thread: https://www.fordbarn.com/forum/showthread.php?t=88541 I have also added a mechanical oil pressure gauge to monitor that more precisely.

Great idea, what temps do you feel are correct on the highway and slower in town?

[markivpedalpusher]

Newbie to flat heads and my 40 pickup is running hot, questions: Do the after market temp gauges come with the temp sensor? Or do I need to buy the sensor separate? Any recommendations where to purchase the sensors for a 40 ford pickup converted to 12 volt?

Looks like the auto zone temp gauges above work. Any other recommendations for after market temp gauges?

Thanks in advance !!

[tubman]

The "mechanical" (non-electric) gauges come with sending bulb that screws into the engine (it will also have and adapter or two with it) on the end of a long flexible tube. I have a SunPro gauge (like Henry shows) on my engine test stand and I believe the flexible tube is at least 6 feet long. I just looped it and used tie-wraps to keep it out of the way.SunPro gauges are pretty cheap and maligned by some, but they have worked fine for me. If you look hard enough, I believe you can get them with black faces. I don't think I've never seen an aftermarket electric temp gauge, so I can't help you there.

[FireEngineMike]

Hopefully the bolt you mention is just the OEM plug (11/16" hex), as was mine. I second the (Sunpro) mechanical gauge approach. The kit I bought (Sunpro CP8217) had the correct threaded adapter for the head. Note that the hex required a 16 MM socket/wrench (between 5/8" and 11/16") to tighten. I bought a "51" 6-volt bulb from BulbTown.com to replace the 12-volt bulb in the kit. I bought replacements for all the 6-volt bulbs used in my 1940 fire engine at the same time.

[Seth Swoboda]

I just installed an autometer brand mechanical temp gauge on an 8ba engine. Make sure the two mounting fittings that thread into the head are 3/8in NPT. Autometer did not and I had to buy it separately. For the price of the gauge you think they would include a 3/8th but they only provide you with 1/2in NPT.

I also have a mechanical temp gauge on a 59A engine and highway speeds it runs about 170 degrees and if I slow up for traffic it will climb to 180. Depends on speed of course. On a hot humid day sitting still it can get warm.

[markivpedalpusher]

Thanks for your help. The Sunpro CP8217 seem like a good price.

[Seth Swoboda]

Originally Posted by markivpedalpusher

Thanks for your help. The Sunpro CP8217 seem like a good price.

A lot better than what I paid for the autometer that didn't come with the correct mounting fittings.

[markivpedalpusher]

Will I need any type of thread sealant to install the sensors?

[Old Henry]

On the mechanical sensor any sealant will do, Teflon tape, pipe dope, etc. But, if you're replacing an electric sensor there has to be electrical contact through the threads to the engine block to ground the circuit so I use nothing and it still doesn't leak.

[markivpedalpusher]

That's really good info, thanks much !!

[morrisgauge]

In theory, your mechanical temperature gauge adapter/bulb/jam nut should not require any sealant as the adapter is pipe thread and the bulb seats on a shoulder within the adapter, much like a valve. If the threading on your sender hole is damaged you might consider repair or threading to the next adapter size up. Also, use a brass adapter, the steel ones keep our shop in business.

www.morrisgauge.com

[Old Henry]

Originally Posted by Viroid

Great idea, what temps do you feel are correct on the highway and slower in town?

Minimum temperature should be what your thermostat is set at. That would be ideal if that could be maintained but the temperature rises with many circumstances including outside ambient temperature, speed, wind direction (is more important than may be thought), steepness of a climb, etc. I know that with my 4 lb. radiator cap I can get up to 225° before boiling the coolant out. So, anything between my thermostat setting of 170° and that boil out temperature is fine with me.

[Johnnydidd]

I just purchased 50/50 antifreeze on the back of the container it shows boiling at 265 deg. I use a 7lb pressure cap on my 53, I also use a mechanical gauge, the markings on a mechanical are better.

[markivpedalpusher]

Since I don't know what radiator cap I have I'm thinking I should replace it. I was told 6lb for a 40 ford pickup. Would this be correct?