generator ????

imported_Terry29-26 · May 27th, 2003

Need some help with generator problem. 1929 Buick will not charge when started. Drive about 10 miles and the amp gage slowly moves to +, 1 to 2 amps. At forty miles/hour it will show 10 amps. Back off the gas and it goes to 15 amps. Push the gas peddle down and the gharging rate drops the faster I go. Hit the brakes or turn on the lites and amp meter goes to 0 and it starts all over again. Any one out there Know about these charging systems?

Terry29-26

imported_bjr · May 27th, 2003

Check for sticky brushes in the generator or a bad cutout. I think these older cars used a cutout insted of a regulator. Brian

Mrbuick714 · May 27th, 2003

Clean the commutator with very fine sand paper

imported_Charles2 · May 27th, 2003

You may have a number of possible problems. First, it may be that the ammeter is defective; a competent auto electrical shop can test it for you in the car. But, I don't think this is the problem. I suspect the problem is in the generator. So, next, check the brushes in the generator. It sounds as if they are not making good contact with the commutator. If the commutator is lumpy or out-of-round, and the brush springs are weak then the faster the generator spins, the less contact the brushes will make with the commutator. Basically, they will "bounce" out of contact. Because of this, the faster you go, the lower your current output will be. I think this is your problem. Next, I'm not sure when Buick went over to using a voltage regulator but I think it was after 1929. If there is a rectangular box on top of the generator about 1 1/2" x 2 1/2" then you most likely have a cutout. A voltage regulator is larger and usually not mounted on the generator. The cutout serves to open the charging circuit when the engine is not running and keeps the battery from discharging through the generator. If you have a cutout and it is stuck, you will know it since your generator will cook. But, if you have a cutout, then the generator output was controlled by a third brush in the generator. This brush is adjustable to regulate the current through the field coils and thus the generator output. This third brush may also be bouncing and causing reduced output at higher rpm.

My recommendation would be to take the generator off the car and disassemble it. Have the armature tested for shorted windings; have the commutator turned and have the mica separators undercut. Clean the brush mounting plate and check the springs for strength and free movement. Unless the brushes are nearly new (usually about 1" long) you should probably replace them; they may be hard to find. Replace the bearings or bushings that support the armature and finally, have the field coils tested for continuity and possible internal shorts. Then reassemble. If you don't have the tools for this job, a good local auto electric shop can do all the above at a reasonable cost. This will give you a rebuilt generator and will most probably solve your problem. Good luck with it.

imported_Terry29-26 · May 28th, 2003

Thanks to all::

You told me what I didn't want to hear. I was hopeing for a quick fix but I will have to take the Gen. off and rebuild it. Yes it dose have a cutout and third brush. I have finaly set the car up to get 14 miles/gal and didn,t want to disturb the dist. I will post some photos when I take it apart. Hopfully to day.

Thanks to all for the help< Terry29-26

Albert · May 28th, 2003

Some generator the third brush you can adjust the position to change the voltage output and the rate of charge. This was common practice in tha fall to increase the output to increase the generators output to supply the headlights as well as recharge the battery, as in may -sept you had much longer days and only needed ignition. You might want to attach a digital voltmeter across the battery and see what it says, the amp guage swinging + is normal as it only shows how much current is comming from or going to the battery not how much is really comming from the generator, to do that the meter would half to be in the lead from the generator to the battery.

Mrbuick714 · May 30th, 2003

Our 1930 Buick probably had a similar generator.It had a resistor just insde the band opening. The purpose of it was to cut back the charging rate when the generator got hot. As it turned out,the resistor became open,and at times,there was literally,NO output. You can run a jumper,temporarily.to the field itself,which would show that the generator itself,other than the resistor,was O K. Regards,Ralph

imported_Terry29-26 · May 31st, 2003

HI All:

Here are the photos I said I would send. These are the parts I had to replace to get the generator operating again. Seams that the Thermostat assembly has not been operating for a long time and the gen. was only operating on the resistor circit because it never put out more than 10 amps. Since replacing the thermostat and the resistor the gen. puts out 19 amps when eng.is started. My service manual states that when the gen. gets to opperating temp. the out put should drop to 7 to 10 amps. So far it hasn't fallen to the 7 to 10 amps. My book says that the themostat is not addjustable in the feild but should be sent to a UNITED SERVISE CENTER to be reset. (Anyone know where there is a United Servise center still operating????)

After Removing the gen and all that that intails I found out that my problem could have been resolved by removing the band around the gen. and removing 3 small screws. I was looking for a quick fix. There is one for this problem but I had to learn it the hard way.

I had to rob the parts from my 1932 to fix the 29 so I need to find some replacement parts. Anyone out there have the following.

Brushes Main 2 # 35287
Third # 35288
Resistance Thermostate # 807180
Thermostate Assembly # 820513
Cut-out Relay #1867781

Have a good day all and hope to see you in Flint.

Terry29-26

Mrbuick714 · May 31st, 2003

You could take a small rheostat, hook one lead to the field (The wire which normally went to the resistor),ground the other terminal of the rheostat,then you could adjust your charging rate while driving. By all means,keep the elderly generator from doing any more than absolutely necessary. Parts are getting harder to come by each day.I recently lost my armature winding supplier, nobody wants to do it anymore. Started repairing generators in 1936,still at it.mrbuick714@webtv.net