Denver T-Bird

'57 Thunderbird generator/regulator

Recommended Posts

I am new to having an "older" car.   I took the generator and voltage regulator to a shop to be tested. The generator was good, the regulator tested bad.  I replaced the regulator and tried to polarize the generator by touching the regulator field wire to the battery wire for about 2 seconds (per instructions in the shop manual.)   When the car is not running, the voltage across the battery is about 13 Volts, after starting the engine the voltage drops to 12.7.   If I remove the positive battery cable when the engine is running it dies.  Any suggestions? 

 

I have heard of other methods to polarize the generator - what is the most reliable way to do this?

Share this post


Link to post
Share on other sites

This sound normal.  Starting the car will pull the battery voltage down and a generator does not charge much at idle.  Depending on the car, the battery may have to be in the circuit for the car to run.  Take the car out for a drive an then check the volts.

Share this post


Link to post
Share on other sites

The engine was running at about 1800+ RPM when I measured the 12.7V.   I was expecting around 14V when running at that speed.  Any other measurements I could make to verify correct operation?   Thanks

Share this post


Link to post
Share on other sites

61polara, I have a 76 dodge power wagon, it came with an electronic control unit, and I'm switching to points and condenser. Do you know if my alternator will still work? And if a regular dodge mechanical voltage regulator will handle the current from alt. to v.r.? I found a v.r. from rock auto made by standard that is rated for 40 amps, just want to be sure I'm getting the right stuff. If you don't know, would you be able to point me in the right direction? Thanks James 

Share this post


Link to post
Share on other sites

James, I think it would be a good idea if you would start a separate thread in this section.  That way each persons questions can be addressed separately.   

Share this post


Link to post
Share on other sites
14 hours ago, Denver T-Bird said:

I am new to having an "older" car.   I took the generator and voltage regulator to a shop to be tested. The generator was good, the regulator tested bad.  I replaced the regulator and tried to polarize the generator by touching the regulator field wire to the battery wire for about 2 seconds (per instructions in the shopmanual.)   When the car is not running, the voltage across the battery is about 13 Volts, after starting the engine the voltage drops to 12.7.   If I remove the positive battery cable when the engine is running it dies.  Any suggestions? 

 

I have heard of other methods to polarize the generator - what is the most reliable way to do this?

You  MUST disconnect the field wire to polarize the generator. Otherwise you will burn the contacts in the voltage regulator (ie: destroy it!)

Share this post


Link to post
Share on other sites
21 hours ago, Denver T-Bird said:

I replaced the regulator and tried to polarize the generator by touching the regulator field wire to the battery wire for about 2 seconds (per instructions in the shop manual.)

 

I think you should burn your shop manual.......2 seconds in electrical speed is an eternity and way more than enough to have taken out the regulator.

All it takes is a quick (as in almost instantaneous) touch of the hot wire to polarize the generator.

Too late now but did you polarize the regulator as well?

  • Like 1

Share this post


Link to post
Share on other sites

This is my source for info : A good library plus 75 years in repair shop with 9 years as Lincoln/Mercury Service Mgr.

 

Re activated a pretty little 1934 Ford roadster yesterday!003.thumb.JPG.d132a01f9f6a9d3c1350ee12696e3c2a.JPG

001.JPG

002.JPG

  • Like 1

Share this post


Link to post
Share on other sites

I made some measurement at the regulator and got the following:

 

Voltages

RPM     1800           800

Batt.      13.5V       13.4V

Field.      mV

Arm.     13.8V          13.6V

 

Resistance (removed the positive cable from  the battery)

Batt.  48.5K ohms

Field.   2 ohms

Arm.   0.6 ohms

 

Thanks

Edited by Denver T-Bird
Update (see edit history)

Share this post


Link to post
Share on other sites

With everything hooked up, and with clean and tight battery cables,  have the engine running at idle and measure the battery voltage at the battery.  Then increase engine speed to about 1500 rpm and again record battery voltage.  Does battery voltage increase at higher rpm?  If battery is good and strong and fully charged, change in voltage can be small.

 

Part 2 - repeat above test with headlights on.  This will place a load on the charging system.  At idle, battery voltage should be lower and should increase when rpms are increased.  If generator does not put out at least 13v at higher engine speed, then regulator or generator may be suspect.  The regulator also needs to be well grounded to the car.

 

I do not have a t-bird.  The above tests are from my experiences with generator equipped old cars.

Share this post


Link to post
Share on other sites

I think the battery is charging now.  Battery voltage initially was 12.8V (engine not running), then 12.6V at 800 rpm , and 14V  at 2000 rpm. 

 

Now back to the original problem .... The turn signals blow a 7 amp fuse and takes out the flasher.  I have not found an obvious short or worn wires.  The first thought was that fuse was taken out by over current from a faulty regulator, but now that the regulator has been replaced not sure where to go.   The parking lights work.  Is there a way for the signal switch to cause an issue?

 

Thanks to all for the help.

Share this post


Link to post
Share on other sites

Seems like a short in the turn signal wiring.  Each bulb front and back has a separate contact for the blinker function.  The back bulbs also function as the stop lights.  Do you blow a fuse when the brakes are applied?  Do the brake lights work?  If brake lights work then it seems the issue is in the front.  I would look at the front bulb wiring as the only time it’s brighter bulb elements are on is when the turn signals are activated with the turn signal switch.  Post an update on the brake test.

Share this post


Link to post
Share on other sites

The break lights work and do not blow a fuse - I believe that they are not connected with the turn signal fuse.  The signal lights work when just sitting but the fuse blows when driving around. Maybe the short happens when the wheel is turned??

 

Thanks

Share this post


Link to post
Share on other sites

Driving around could be vibrations in the bulb sockets or wiring.  If due to short in steering column, you should be able to test that sitting still.  Turn wheel from extreme left to extreme right with turn signal on.  You may want to have a supply of fuses and turn signal flashers for troubleshooting use!

Share this post


Link to post
Share on other sites

What bulbs are you using?  Is it left turns or right turns or both? Does the fuse blow just by driving around with out turn signal use?

Share this post


Link to post
Share on other sites

Most turn signal bulbs are 1157 dual element. The low wattage element is the parking light / running light and the high wattage element is the brake / turn signal function.  The high wattage element is about 28 watts per bulb when lit x2 for front and back so about 56 watts.  Using ohms law that means at 12v supply you need about 5 amps to operate the turn signals which is ok for a 7 amp fuse.  

 

You can lower your wattage use and maybe help with your troubleshooting by installing LED versions of the 1157 bulb in either the front OR back sockets.  If you replace all four bulbs the turn signals probably won’t work as the flasher requires the higher current draw of the standard filament bulbs to operate.

 

Hope this helps!

Terry

Share this post


Link to post
Share on other sites

I don't understand why the flasher gets taken out - it is down from fuse.  For trouble shooting can I connect the two wires at the flasher to see what is blowing the fuse then add the flasher after the fuse is fixed?

 

Thanks

Share this post


Link to post
Share on other sites
6 minutes ago, Denver T-Bird said:

I don't understand why the flasher gets taken out - it is down from fuse.  For trouble shooting can I connect the two wires at the flasher to see what is blowing the fuse then add the flasher after the fuse is fixed?

 

Thanks

Sorry, im not sure about the connection you propose.  The flasher needs the current to the bulb to operate.  The old flashers work by heat, that is, the bulb current through an element inside the flasher causes heat and that heat in turn opens and closes the circuit.  If a bulb burns out the flasher will not operate as you might have seen before this problem.

 

The fact you are killing the flasher indicates you are drawing a LOT of current in the bulb circuit, so much and so quickly even the fuse can’t protect it.  I makes me think there is a dead short to ground somewhere.  The led bulb idea was to allow just some low value of current to be drawn as you try to find the issue.  

Share this post


Link to post
Share on other sites

Sitting in the garage , ACC on, both signals worked consistently.  Started the car and turned the wheel far right with the signal on then turned the wheel far left with the signal on- all OK.  I took the car out for a drive.  I used the right signal many times with no problem.  Next tried the left signal, it worked once or twice then the fuse blew.  The flasher is still working.  
Only thing I can think of is to turn on the left flasher and rattle wires around until the left signal stops/fuse blows.

Share this post


Link to post
Share on other sites

Agreed, seems to be in the left side. Check the sockets and wiring.  Remove the bulbs and look inside the sockets for corrosion.  Tug on some wires. Is the bulb loose in the socket?  I’m thinking the voltage to the turn signal part of the bulb is getting a direct path to ground.  May have to CAREFULLY move wires under dash too.  Making some progress!

Share this post


Link to post
Share on other sites

Removed the left signal light and used some sand paper to clean up the inside of the socket.  Turned the key to ACC and turned on the left signal.  Started rattling wires around, first under the hood- nothing happened, still flashing, then under the dash, nothing.  Moved to the trunk and rattled wires on the left side - nothing, still flashing.  Opened and shut the drivers door and the fuse blew, also took out the flasher.  Still trying to track this down ....

Share this post


Link to post
Share on other sites

The flasher has two prongs, correct?  I think I understand your idea for substituting a wire for the flasher.  This might be an option but NOT with voltage applied as the flasher burning up may be protecting you from a burnt wiring harness if it was not there.  Wiring  a fuse in place of the flasher for testing might be a better option, it would be easier than constantly replacing the flasher.  Still thinking about a test procedure to isolate the problem.

Share this post


Link to post
Share on other sites

Seem like the problem is “fixed” with a new fuse and flasher until the next time a bump is encountered with the left turn signal on so it’s not a continuous condition.  You could use a wire or a wire with a fuse in it to bypass the flasher while working on it. I’m thinking the problem might be in the steering column wires or front turn signal.  I think the tail light wiring is ok in that you never loose the brake light fuse.  If the rear lights were a problem the stoplight fuse should be blowing too.

 

If you have the wiring diagram for the car you might be able to trace the wires that are energized when the turn signal is on.  There are plugs involved and switches and wires in the steering column to investigate. I will be glad to try and answer any questions you might have.  A 57 Tbird specific sight might have ideas too.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now