Hi All- How do I test an original 6v temp gauge to see where the problem lies. I put in a rebuilt engine with a different sensor and still the needle hangs out at "H" - always. My buddy wants me to abandon the gauge and add an aux hanging from the dash.

Also - are there volt meter-type gauges that go as low as 6V? Seems I'm only finding the 12v variety.

Hate to give up on my stock stuff.

 

since the sensor is just basically a variable resistor, if you get a rheostat or some other type of resistor that you can adjust, then you can hook up your gauge to a 6 volt source and see if the needle moves or just stays in one spot. usually if it is stuck at H, then the guage is grounded or there is a ground somewhere in line.

as for what the resistence reguired for the variable resistor, i don't know that off hand. someone else maybe has that info available.

rgds
Mike

 

You can also use two 1.5 volt batteries (D, C, AA, AAA, etc) in series across the terminals, with the negative to the post that the sending unit goes to. The needle should swing, probably just past the halfway mark. At least you'll know if the gauge is working or not.
As a general rule, if the gauge is getting power and swings to "full" or "hot" when the key is turned on, the sending unit circuit is open. If it stays on "cold" or "empty", the sending unit circuit is shorted to ground.
Good Luck!

 

what did people do when they changed to 12V? They obviously didn't trsh all cars made before a certain point...what does a "12v conversion" consist of?

 

Hi Erinaldi,

How about my two cents!

First if I'm not mistaken, the electric temp gauge defaults to full hot when the truck is turned off. And I think it's the only one of the gauges that does that.

First: 12V. They make a number of 6V to12V resistors that mount on the backs of the gauges if you want to continue to use stock gauges. I have one on my gas gauge and it works perfectly. The induction loop AMP gauge will work on both 6 and 12 volt.

You can test your gauge as was mentioned before with a 1.5 AA cell battery. It should be just enough to move it. Question, when you installed the sending unit did you use teflon tape? That's a no no!

Here is another option that I like if you have the gumption to do it. You can buy the off the shelf mechanical oil pressure and and temp gauges and incorporate them into your stock set up with the stock gauge faces and they will work reliably and true no matter what voltage you are using.

I have done a couple conversions myself, but the one converted in my truck now, my dad did. He used to post here and has a gallery on this conversion. Let me see if I can get a URL for it and edit it back in. If not send me a PM with your real e-mail and I'll send you the pictures and the write up on how to do it. In the mean time, here is a picture of my gauges. The temp and oil pressure are both mechanical off the shelf gauges.

Edit in: Try this link to get to the gallery: https://www.ford-trucks.com/user_gal...&albumid=32285

Works!

Best wishes,

Julie!

 

I have always ran a jumper wire from the sender wire (in the engine compartment) then
get in the truck and ground the wire, then quickly turn the key on and the gauge quickly
goes to C cold. I think whatever engine is in there ,you have to use the sender made
for the gauge. All Ford products before the event of 12Vts in 56 the temp gauge always
went to hot with the ign off. All my trucks I changed to 12V neg ground. Years ago
I found that any 70s 80s Ford temp gauges will slide right into the face plate of the pre
12vt era. however the sender for that gauge must be used. Temp gauges and wipers
and ill fitting hoods have been a thorn to me since these trucks were new.

 

you may just have the wrong sender
I know if you use a 6v sender in a 12v system the guage will work perfect only reading will be backwards

 

Fatford's suggestion worked! Using the battery test the needle came to life - first time in the four years I owned the 55. I'll run a new wire from the sender and that should do it. Thanks! This forum's the best!

 

erinaldi,
Glad that worked for you. I would verify you have power at the gauge (~6 volts) and then make sure the sending unit is correct for the gauge.
If you have converted to 12 volts, you will need an "instrument regulator" or something like that. In '56 and on through the 70's, the instruments remained 6 volt and there is a regulator that mounted behind the instrument panel that supplied the lower voltage for the gauges. Do a search and you'll find more info. If you look back far enough (3-5 years) there is an explanation by Earl (George) that explains how this "regulator" works. It's not really a regulator, but I don't know what Ford called it. Some sort of thermally activated switch.
The wiring has to be correct The sending unit resistance has to be correct for the gauge and the supplied voltage also has to be correct or things will not read properly.
Good Luck!

 

Hello everyone, I am new to site but not the industry, and love the FTE form. I have a 52 F1 with 2 temp senders, how can I make a mechanical gauge setup like talked about in this form if most mechanical gauges have the sender already attached for 1 sender spot. Or am I forced to go the voltage drop route with my original gauges? Or just add another temp gauge, but that would defeat the purpose of doing with my original gauges. Any input would be great thanks.

 

Remhaust,

The original temp guage setup on the flathead V8's used two senders because the flatty basically had two separate cooling systems (and most importantly two thermostats) within the block. The only place that the coolant mixed was in the radiator. The guage really doesn't read from both senders under normal conditions, though. The one with only one terminal and wire on it is the one that the guage reads from. The one in the other head that has two terminals is basically just an overtemp switch. The variable voltage signal from the single terminal sender normally just passes through the crossover wire and second sender on it's way to the guage. However, if the bank that the two terminal sender is in overheats, a set of contacts in that sender closes and shorts the guage feed to ground. That causes the guage to read full scale HOT.

For what you want to do, there is no reason you can't just run one regular mechanical guage. You won't have any indication for the other bank, but if it starts getting hot, the bank you are reading from will increase in temperature also albeit at a slower rate.

 

Thanks for the input, thats kinda what I was thinking also. Also I read hear that if i use the original 6v senders with my 12v system they would work just read backwards? so what does he/she mean exactly, or how do i change, or just do as originally planned? Also for the fuel gauge Iam still assuming I need to put a voltage regulator/drop for that particular circuit, or is there sum other means that ive missed? Thanks again

 

Where did you read that? What foooey!

First of all you need to be a little more specific about your truck. What engine do you have? Still the flathead or something new. Second you need to specify if you have a 6 volt or 12 volt electrical system and if you are using the original electric or mechanical gauges. In short what have you got and what are you trying to do? Trying to get OEM gauges to work?

If you have changed from 6 Volt positive ground to 12 Volt negative ground and you want to use your original electric gauges, then you have to voltage reduce ALL of them accept the AMMETER - which is actually just an indicator of charge or discharge. The Ammeter is an induction loop sensor that will work with 6 or 12 volt.

If you change from positive ground to negative ground - change polarity, you have to reverse teh direction of the wire running through the induction loop or it reads backwards - reverse polarity, reverse reading.

Even if you change from 6 volt positive ground to 12 volt negative ground, you have to keep all of the original sending units that are specifically for the gauges. This will work with the flathead and two temperature senders units. They are different and have different functions but still work with the gauge reducers.

Lastly, the gauges were manufactured to have the needle rest in a certain position when they do not have power supplied. On theoil pressure this is at the "0" psi position, and on the Temp gauge this is on "H." The reason for this is because it is the "worst case" indication on the gauge. If htere is a power failure of some sort to the gauge it will alert the driver that there is an emergency situation (might not actually be an overheat or a loss of oil pressure) but it will get his attention and say "something is wrong, pull over and check.

This is a subject that has been so often, and so clearly beat to death, that I'm not sure I understand why there is still confusion about it.

Same answer every time: use the original senders with the OEM gauges reduced by installing gauge reducers to handle 12 volts-reverse the direction of travel of the wire going through the ammeter loop, and go for a drive.

Heres a link on the reducer installation:

https://www.ford-trucks.com/forums/8...12-volt-2.html

If you want to convert to mechanical gauges, you will still ahve to keep the electric fuel gauge and the ammeter will still work as it is, so all you ar edoing is converting Oil and Temp. I have a gallery that shows the process for installing new oil and temp gauge works in your original 51/52 gauges and installing those in your original cluster. See my gallery on that.

That is exactly how my truck is set up, here's a picture of the gauges after conversion.



Note that with a mechanical gauge the temp reading is always true and the needle rests on cold when th eengine is cold - key on or not.

If you still have a flathead V8 with two sending units, you have a choice: either stick withthe electric gauges and reduce it using both sending units, or go mechanical and pick one side and hope it indicates close enough for the other. I'd reduce the electric gauges

Welcome to FTE by the way!

 

Not true for Bonus Built trucks, not entirely sure but I think mid-50s are the same as BB.

see attached

 

OK, I was off a little on the shorting to ground making it run full hot, but the concept was right. It's been awhile since I've played with one of my flatties, so I'm working from memory here!