1955 temp gauge goes past HOT

[Gpaws55Bird]

getting my grandpas 55 running again. car has been converted to 12v. temp gauge goes past H. i’ve read that this is because it’s a 6V sensor that’s getting 12V. how can i fix this? some sort of resister?

here’s a picture of the wiring. it has seen better days and is cracked in multiple places with exposed copper.

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[jack-in-sac]

Replacing the old cracked wiring with new wiring would be a great first step. Likewise make sure the tab showing in your picture does not touch anything except the red/white wire. I see you have 2 spade connectors on it. You only need the one.
If you replace the sensor with a 12v sensor make sure you are ordering a sensor that is the same size as your 6v sensor.
Is your car overheating? When running "hot" is it puking coolant? If it is not pushing coolant out of the radiator overflow it is not overheating. The fill level on the correct radiator is to the baffle in the radiator upper tank. You can see the baffle when you remove the radiator cap and look into the filler neck. Filling the radiator more than to that level usually insure you will lose coolant until the cold level is lowered to that baffle.
Your 6V gauges can operate on a 12 volt system as well, but you’ll want to install a voltage reducer in-line on your gauge’s power circuit.
Good luck and happy motoring. J.

 

[Gpaws55Bird]

i’m limited to the amount of responses per day… forgive me moderators, don’t take this down. trying to give my grandpa a smile by letting him ride in his bird.

i have another problem.

1955 bird with 292 and 2 speed auto and holley 4000 teapot.

idle with choke off in neutral and park is above 1000 rpm. when shifting down to reverse or drive it drops drastically to 500 and makes a big clunk noise. to my knowledge there is only one idle speed screw for when it is hot. and that is on the back of the linkage

is there a kick down cable or something.

after this post i won’t be able to respond until tomorrow.

 

[Dick Rupp]

Before you shift to reverse, start with drive, then shift to reverse. My '55 does the same clunk if shifted to reverse first. Idle speed should be 450 / 500 rpm in gear at normal operating temperature

 

[Gpaws55Bird]

Before you shift to reverse, start with drive, then shift to reverse. My '55 does the same clunk if shifted to reverse first. Idle speed should be 450 / 500 rpm in gear at normal operating temperature

Replacing the old cracked wiring with new wiring would be a great first step. Likewise make sure the tab showing in your picture does not touch anything except the red/white wire. I see you have 2 spade connectors on it. You only need the one.
If you replace the sensor with a 12v sensor make sure you are ordering a sensor that is the same size as your 6v sensor.
Is your car overheating? When running "hot" is it puking coolant? If it is not pushing coolant out of the radiator overflow it is not overheating. The fill level on the correct radiator is to the baffle in the radiator upper tank. You can see the baffle when you remove the radiator cap and look into the filler neck. Filling the radiator more than to that level usually insure you will lose coolant until the cold level is lowered to that baffle.
Your 6V gauges can operate on a 12 volt system as well, but you’ll want to install a voltage reducer in-line on your gauge’s power circuit.
Good luck and happy motoring. J.

to mr rupp: after shifting through reverse and drive a couple of times it doesn’t make as bad of a noise. but i’m still wondering if there’s a way to make park/neutral idle speed any lower. i’m going to let the car warm up in park and then set idle speed after about 5-10 minutes of idling. i don’t have a working temp gauge so i’m scared the thermostat is stuck closed. i’m going to feel the top rad hose to see if it gets too hot. i don’t have a temp sensor gun. i will then set idle speed around that rpm once hot.

is it normal for park idle speed to be that high?

to mr jack in sac: do you know of a source i can get a 12v sensor? is it as easy as just the sensor itself? or do i need to get a 6v sensor and add a resister inline? does the wiring need to change? (if it weren’t cracked) speaking of the wiring, i never know how to properly execute old wiring. because that wire for the temp gauge goes into wire loom. if i were to properly do it i would completely replace that wire, but i don’t want to destroy the harness. should i cut it back to where it isn’t cracked and try to attach a new wire to it?

to my knowledge the car isn’t running hot. it’s only ran for a couple minutes most. in the time that it did run, i noticed it has an oil leak. my guess is the rear main.. thats a pain. the coolant is slightly low. i will fill it up. the car has a lot of vapor coming out of the vent in the engine bay. i’m guessing it may burn oil. but the thing starts up to darn easy and has 40psi of oil pressure according to an aftermarket gauge that i didn’t see before. so it has good compression. i will let it warm up and keep an eye on the overflow. i might also go get an oil change from o’reilly and a temp gun from harbor freight.


this is my last post for the next 24 hours. i can respond with likes. i will be working on this car for the rest of the day, trying to get it drivable. IF I HAVE TO, I will edit this post most likely as a response to future posts. please keep an eye out. thank you all, couldn’t do this without help.

 

[Ward 57]

i’m limited to the amount of responses per day… forgive me moderators, don’t take this down. trying to give my grandpa a smile by letting him ride in his bird.

i have another problem.

1955 bird with 292 and 2 speed auto and holley 4000 teapot.

idle with choke off in neutral and park is above 1000 rpm. when shifting down to reverse or drive it drops drastically to 500 and makes a big clunk noise. to my knowledge there is only one idle speed screw for when it is hot. and that is on the back of the linkage

is there a kick down cable or something.

after this post i won’t be able to respond until tomorrow.

That neutral Idle sounds really high. I think it should be closer to 750-800 RPM. Even though the choke is off, the high idle screw may need a little adjustment. Just the bump from putting it in gear may be enough to get the screw to drop off the choke cam hence the normal actually low idle in gear. I'm not really familiar with the teapot carbs but I would think any carb would have a high speed and a low speed adjustment.

 

[jack-in-sac]

to mr rupp: after shifting through reverse and drive a couple of times it doesn’t make as bad of a noise. but i’m still wondering if there’s a way to make park/neutral idle speed any lower. i’m going to let the car warm up in park and then set idle speed after about 5-10 minutes of idling. i don’t have a working temp gauge so i’m scared the thermostat is stuck closed. i’m going to feel the top rad hose to see if it gets too hot. i don’t have a temp sensor gun. i will then set idle speed around that rpm once hot.

is it normal for park idle speed to be that high?

to mr jack in sac: do you know of a source i can get a 12v sensor? is it as easy as just the sensor itself? or do i need to get a 6v sensor and add a resister inline? does the wiring need to change? (if it weren’t cracked) speaking of the wiring, i never know how to properly execute old wiring. because that wire for the temp gauge goes into wire loom. if i were to properly do it i would completely replace that wire, but i don’t want to destroy the harness. should i cut it back to where it isn’t cracked and try to attach a new wire to it?

to my knowledge the car isn’t running hot. it’s only ran for a couple minutes most. in the time that it did run, i noticed it has an oil leak. my guess is the rear main.. thats a pain. the coolant is slightly low. i will fill it up. the car has a lot of vapor coming out of the vent in the engine bay. i’m guessing it may burn oil. but the thing starts up to darn easy and has 40psi of oil pressure according to an aftermarket gauge that i didn’t see before. so it has good compression. i will let it warm up and keep an eye on the overflow. i might also go get an oil change from o’reilly and a temp gun from harbor freight.


this is my last post for the next 24 hours. i can respond with likes. i will be working on this car for the rest of the day, trying to get it drivable. IF I HAVE TO, I will edit this post most likely as a response to future posts. please keep an eye out. thank you all, couldn’t do this without help.

If you get a 12v sensor that is the same size as your 6v sensor it is just remove and replace. By the way don't use any sealant on the sensor. You will then effectively break the ground contact between the sensor body and the cylinder head. take the old one off and go to the parts store to replace it.

 

[dmsfrr]

The '57+ Temp sensors are smaller than the earlier versions. They aren't electrically interchangeable either.
An (original) 12v Temp sensor the same size as the one you have will be the '56 version. The electrical specs will not be the same to match up with a '55 dash temp gauge. It most likely will not indicate correctly.
The original '55 Temp gauge should be paired with a '55 Temp sensor to have the best chance for a correct indication on the dash gauge.
The originals work on a heat sensitive switched on/off circuit in the sensor, not a variable resistor. They aren't voltage sensitive, the heated contacts self-regulate 99% of the time.

"The fuel and temp gauges will work on 6 or 12 V and are not polarity sensitive."
quoted from the technical section of a well known Thunderbird club website that has copyright protection so I'll not post a copy of the whole article here.
.

 

[dmsfrr]

... the coolant is slightly low. i will fill it up. ...

It's supposed to be about an inch or very slightly more below the filler cap to allow for expansion as the coolant heats up, it's like a built-in overflow tank. Don't fill up more than that, it will just spit back out.
Use a hand-held infrared thermometer on the thermostat housing to check the actual temperature. The original dash gauges can read hotter than the engine / coolant actually is as they get older.
It's possible the thermostat is stuck shut??? Under normal conditions unless it's blowing coolant out it isn't actually overheating.

 

[doug7740]

getting my grandpas 55 running again. car has been converted to 12v. temp gauge goes past H. i’ve read that this is because it’s a 6V sensor that’s getting 12V. how can i fix this? some sort of resister?

Is your problem with both the temperature and fuel gauges? If the 6 volt gauges do not work when the 12 volt conversion was made, install a 10 ohm 10 watt wire wound resistor between the gauges and the power supply to gauges. If the gauges still do not work it may be necessary to replace the gauges and the sending units with 1956 12 volt units.

doug7740
1955 Thunderbird Blue

 

[doug7740]

I have another problem.

1955 bird with 292 and 2 speed auto and holley 4000 teapot.

Idle with choke off in neutral and park is above 1000 rpm. when shifting down to reverse or drive it drops drastically to 500 and makes a big clunk noise. to my knowledge there is only one idle speed screw for when it is hot. and that is on the back of the linkage

​

As I told you on your "1955 help needed with teapot rebuild" post:

There is a small paper gasket that fits between the main body and the throttle body. If you over torque the two large throttle body screws, it will distort the main body contact to the throttle body, which will cause a carburetor vacuum leak resulting in an idle speed that is too fast.



Sometimes you can check for this leakage by running at idle speed and sealing the area behind the choke plates with your thumb and finger. In most cases the fit between the main body and throttle body can be corrected by installing two gaskets between the main body and throttle body to obtain a proper seal.

doug7740
1955 Thunderbird Blue