If  nothing else works, I believe you could use a '55 guage & sender

with the voltage regulator.

55f100

West Monroe,La.

I have an NOS '56 Mercury oil pressure sending unit. Please e-mail me at glrichards56@gmail.com so I can get your address, etc.

does any one know where to nfind the right sender and condenser  i have used the same part number and gotten 5 differnt ones  please help

i have been looking on line and can find nothing any help

the only differance is i have a 312

help   rod     

1956 was the only year Ford used the full 12 volts on their guages. They did not use a voltage regulator. In 57 they changed to the voltage regulator. That is why the 56 merc and ford temperature senders, oil senders and fuel senders are so unique.

You mentioned that you are seeing 12 volts at the gauge and sender. Since this car is a 12 volt car the voltage you should see at the gauges is 6 volts (if you use a voltmeter you will see that the reading will move up and down, never getting higher than 7 volts). Ford used a voltage reducer on their gauge power feed, when the cars went from 6 to 12 volts, which is a bimetallic set of contacts that opens and closes fast enough to prevent the voltage from getting much past 6 to 7 volts. I would suspect that would cause some inaccuracies in the gauge readings. The reducer is usually mount behind the instrument cluster and serves all the gauges with the exception of the amp gauge.

Why it's not present in the circuit would be anybody's guess.

Jeff Petersen

Tom:



Your readings are lower than mine which is the way we want it to go. Do you have another Merc dash or guage that you could use to prove out your car's guage. The cars guage could be the culprit, however it will go 80 psi when using the other sender which should be maximum scale on the guage. Does the guage go below 0 psi as could could be off-scaled and need the needle adjusted to zero.

SORRY Marv,

My meter wasn't working properly. Got another meter and retested this morning new reading is 25.3 (pic attached).

Must be the dash gage coil.??!! What do you think?

thanks for all your help, Tom

roviwancanobe

Sender no. 75I50is for an idiot light system. When your engine started your guage went full deflection to 80 psi. Those senders only have off/on trip switch internally.



I did a test setup this AM using a NOS Merc sender and my resistance reading differed substantial from yours, almost 1/2.



For 15 psi I got 30.9 ohms, 25 psi 31 ohms, 35 psi 31.3 ohms, 50 psi 31.4 ohms, 60 psi 31.1, 75 psi 30.7 ohms.



It appears that your sender has too much resistance.



Somebody's going to have to help me on this one if you want to use your own sender as you will have to reduce the ohms.



If I remember some of the things I learned a long time ago is if you add resisters in series you add the sum, if you add resisters parallel it is reduced. I do not know what size of resister you will have to place from the other terminal on your sender and place to ground so it is parallel with the sender unit. If yourresistance is reduced in number your guage will increase in deflection to read a higher number.



The sender I used had the 80 on the square for 80 psi. in an Autolite box part number B6A-9278-A .

Thanks guys for your help! This is what I found out--

1) I did a resistance test to the sender and it shows 60 ohms with engine running. Marv. what does this show me?

2) I looked on top of sender, all it says is USA and up with a arrow pointing up and I have it installed that way. (pics attached)

3)I bought the condenser at Advance Auto it is a BWD V10028-------G141Z

4)I ck'd with meter from sender unit post to grd. no reading.

5) I installed another sender no. 75I50 (pic attached) and it shows 80 psi when I start the engine.

6) I ch'd wire from gage again 12 volts.

Do you think theirs a resistor in the gage and 12 volts is to much? I have 12v going in & 12 v coming out to sender.

thanks Tom

roviwancanobe

Tom, the number on the condenser which is strapped and grounded to the sending unit is  FDC18826-A  hope this helps because in the wayyyyyyyyyyyyyyy past when I drove these cars on a regular basis they really wanted this exact type of condenser. If you could just find a good used one it would be worth getting. You would think if all the stars would line up something close would be compatible enough to work ???

-Gary Burnette-