View Full Version : 57 bird gauge problems
11-11-2015, 04:46 PM
I have a problem with my fuel and temperature gauges not working on my 57 bird. I have changed the cvr with e new one from Mac's parts (b9mz-10804-c) and it is grounded did not help. I checked the voltage at cvr, car not running 13 volts in and voltage out is 5.0. I bench tested the gauges with 2 -1.5 volt batteries in series and both worked fine as per ford manual 1/2 on fuel gauge and mid point on temperature gauge.
I also disconnected both sending units, grounded the terminals and both gauges worked as per manual. I checked both fuel and temperature sending units and both ok. I checked voltage at the fuel sending unit with wire off and ignition on. the reading was 5 volts. With sending unit wire hooked up with about 1/2 tank of fuel, the voltage at tank sending unit was approx. 3 volts ,gas gauge showed empty. I disconnected the ground from the cvr and turned key on both gauges started working and climbed up, I turned off the key immediately and gauges went down. also when the key is off the temperature gauge sits on hot. I understand this is normal ? I tried a factory cvr from a 60 ford sunliner witch I know is good and still gauges did not work.
11-11-2015, 07:35 PM
Gauges should swing left so they rest on Empty and Cold with key in off position. Are the gauges correct for a 57 Thunderbird or has someone replaced them?
I am thinking you might have a ground issue but don't understand the temp gauge parking on Hot.
Do you have a ground strap from the back of the engine to the firewall???? Originally on the driver's side head attached by a bolt rearward of the temp sender. Doesn't matter where it is really, just as effective any place as long as you have one.
Has any other wiring been changed?
What modifications do you have to the car?
Do you still have the generator or has an alternator been added?
11-12-2015, 03:32 PM
It sounds as if you have checked everything, but according to my schematics the 57 CVR was not grounded. You have a CVR for the 60-66 Thunderbirds and I don't think it would be the same for your 57. There should be a black wire with a green band coming from the A terminal of the ignition and black with green band wire going to each of the gauges. I would remove the ground wire that you have attached and see if everything works as it should. In 57, I believe that the temp. gauge will fall to the hot side and the fuel will fall to the empty side when the key is off.
11-12-2015, 04:09 PM
As was said, you are using a '59 (B9) and a '60 CVR unit. The actual CVR unit for the '57 Babybird is a B7S-10804-A. They are available from CASCO, but they are not cheap. It is my understanding that the case is grounded, from what I was told. Here is the link to their CVR unit, their Part # 10804.
http://www.parts123.com/parts123/yb.dll?parta~dyndetail~Z5Z5Z50000219a~Z5Z5Z5AAATP~ P82.40~~~~S4HP0VKK5F70239119550c~Z5Z5Z5~Z5Z5Z50000 219a
11-12-2015, 11:11 PM
Lucien, I think I can save you a good bit of money. Rather than buy that OEM B7-10804-A CVR unit from CASCO, check this out. Our intrepid webmaster builds modern solid state CVR units into your OEM CVR unit, guaranteed for life, that you will never have to worry about again. If you become a Paid Member of the Forum, he has a special for you that will save you a good chunk of change. Here are the details. So rather than spending some $83 + shipping, consider this deal! BTW, that B9MZ-10804-C is NOT meant for a Tbird. I have no idea what that is. I did some checking on the Mac site. I see it says it is for '60-'66 Tbirds. However.... MZ is not the code for Tbirds. The letter S=Thunderbird is, as in B7S-10804-A. So I don't know what they are selling.. I see they want $24 for it, but I have been told that many of these CVR units are being made in China these days. One of our biggest Tbird parts houses told me that they have been having problems with these Chinese units failing. Me, I went through 3 of them before I finally put in a solid state CVR unit and have not had a problem since.
If you decide to go this route, I can send you his snail mail information. You will have to send him your OEM CVR unit from your '57 Tbird so he can build the solid state unit in it and send it back to you.
John, thank you for that information. I don't know what the "MZ" stand for, but, but apparently, it works on a '60 Tbird and up.
11-12-2015, 11:22 PM
According to the 1960-64 Master Parts Catalog B9MZ-10804-C is the recommended CVR for all 1960 models including Thunderbirds.
11-12-2015, 11:28 PM
I suspect your fuel gauge circuit is not making its way back through ground. We depend on fifty year-old rusty spot welds to bring the ground back to your battery.
Modern cars use a separate ground wire right in the plug at the tank AND they ground the battery to the body right at the battery. You can simulate some of this on your car:
Ground your battery to the body using a short #10AWG copper stranded wire.
Drill a hole in the corner of your fuel tank and connect a #14AWG stranded copper wire from the fuel tank to the frame using brass or stainless screws and nuts. Be sure your connections are tight. Do it like this:
Notice that the hole is away from the seam weld, anywhere on the outside of the flange.
This should ensure gauge accuracy. Also, pull the sending unit out and physically move the bulb. Some of these have become filled with gasoline over time, also giving false readings on the gauge.
The "at rest" position of your gauges with the key off for some time, should be, "empty" and "cold". You cannot connect gauges the wrong way meaning, they are NOT polarity sensitive. The movements are activated by current which produces heat on a bi-metal strip which deflects the needles. Also, you MUST have a solid ground on your CVR or they will deliver steady 12-volts to your 6-volt gauges. - Dave
Sounds like you have a temperature gauge for a 56 Ford car. They look the same but they will not work with the 57 Tbird
and they rest on hot the 57 Bird rests on cold. The sending units for the two are not compatible either. You may have a
56 car fuel gauge also. They look the same and they rest on empty but the sending units are also different. The CVU regulator was not used on 56 Ford cars nor 56 Tbirds. The 57 gauges are calibrated to read correctly with the 57 Bird CVU regulator.
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