Electrical gremlins giving me fits

[6inline]

I have run into an electrical impass on my 100-6. My Ignition lamp in the speedo was remaining on so I tested the dynamo....no output. I removed the dynamo, opened it up and it looked like burnt toast. No problem, I purchased a new alternator (one in a dynamo case so it looks original), reversed polarity and went to start it. Odd thing, it turned over very slowly. Well, it had been a few weeks since I had driven it, so I hooked up a charger. Once fully charged I gave it another go...nothing. I have 12+ volts at the solenoid, 12+ volts at the starter post, yet it won’t turn over.
Prior to removing the generator it started as always, no problems. Even when the generator was not producing any voltage. Is it possible that reversing polarity might have damaged the starter? I added a ground strap on one of the bell housing bolts just to be sure that I had adequate ground, but it did nothing.
Does anyone have any thoughts before I remove the starter? Any ideas are appreciated.

 

[steveg]

Remove the starter and apply battery current directly to it on the bench. That'll tell you whether it's bad. I had painted mine and when I tested it, didn't have a good contact on the mounting ear, so had to scratch the paint away a little to get a good contact.

 

[Healey Nut]

Not need to remove it just jumper the solenoid with the starter in the car . A big screwdriver or something metal to bridge the gap between the solenoid posts .

 

[Keoke]

Not related to the starter
:But be sure the new Dynamo is polarized before you try to start the car OK

 

[Healey Nut]

Not related to the starter
:But be sure the new Dynamo is polarized before you try to start the car OK

He doesnt have a dynamo , he has an alternator disguised as a dynamo

 

[6inline]

My electrical circuit seems good,and I have 12.8 volts at the starter post when I hit the solenoid, so it has to be the starter. Will remove it tomorrow and give it a good look-see and share my findings. Thanks for the input for those who shared. I appreciate the help.
Tony

 

[Healey Nut]

I would bypass the solenoid as a test first . You could have a high resistance issue that allows voltage to read on a meter but not enough amps passing through the solenoid to crank the starter over .

 

[6inline]

I have not jumped the solenoid, I will try that first. Thanks, I thought that the voltage would indicate it was operating.

 

[Healey Nut]

I have not jumped the solenoid, I will try that first. Thanks, I thought that the voltage would indicate it was operating.

Nope the amount of voltage required to give a reading on a meter is negligible but the amount of power needed to pass through the solenoid contacts to crank the motor is huge in comparison so if the solenoid contacts are pitted old dirty etc then it may show voltage on your meter as your meter doesnt draw current .
All the solenoid is a big electrically controlled light switch .
It maybe the starter but removing the starter only to find it works and its a solenoid issue is lets just say a little annoying .
Take the five minutes to bypass the solenoid as a possibility to save you some frustration time .

 

[RAC68]

Tony,

You indicated you have an alternator built to look like a generator and you had changed polarity. How did you change the polarity of the Alternator? Did you follow polarity change directions from the unit manufacturer? As I understood, the alternator doesn't need to be polarized and charging is not started through magnetism rather, charging is started in an alternator by a trigger current supplied by the dash light circuit when the key is turned before the engine starts. The AC created by the Alternator is then rectified (electronically) to create the DC required.

Again, before starting the car, briefly turn on the key and look to see if the dash light glows. If not, your alternator will not be activated and will not charge.

Just my thoughts,
Ray(64BJ8P1)

 

[6inline]

I changed the car to negative earth, not the polarity of the alternator. All lights come on when key is turned, fuel pump runs, (I did reverse wires to newer fuel pump) and I have ample voltage.

With the race (Indy 500) on today I did not spend much time one garage. I will test solenoid and starter tomorrow while finishing water pump replacement on the other Brit.

 

[6inline]

Happy Memorial Day!
Well, I removed the starter this morning, and it operates just fine when I connect it positive ground, but it does nothing when I connect negative ground. I thought that the starter was not polarity sensitive. Please help me resolve this dilemma. I thought changing to an alternator was going to be a simple task.
Thanks!

 

[Keoke]

Send starter to good repair shop for repair estimate new may be cheaper.

Also check model number of starter stamped in the case with specified model for you car ?

Nevah heard of this before???

 

[6inline]

So, after extensive fiddling with the contacts and connections, the starter turned over on the bench with negative ground connection. I put it back in car and it just seemed like it was barely turning the engine, even though battery voltage was 12.8v. I reversed back to positive earth and turned it over, then back to negative earth and it sounded better. Connected coil and alternator and it fired right up. Reading 13.4v at battery and ignition light is off. All seems well. Took it for a short test run and I think it is OK.
Side note, got the TR6 put back together also. I once again have two operational Brits in the garage!
Cheers!

 

[Healey Nut]

Put a gear reduction starter on her and she will spin like a champ .

 

[Michael Oritt]

You're correct--starters are not polarized but do need good connections in order to carry the starting amperage. From what you're describing you probably had a bad ground that you cured when putting the starter on the bench. This does not require much current and a light ground will work whereas in a starting situation you need a good battery with good connections.

OTOH your starter may be going bad and if you care to stay original take it to a starter shop and they will test it under load, disassemble if necessary and replace or restore as needed. However the best "old fashioned" starter cannot provide the power than that of a gear reduction starter and if your present starter requires some $$ to make it right the money is best spent on a modern starter.

That said, your new gear reduction starter will still want good, clean connections and a well-charged batt is always helpful.

 

[6inline]

It is turning over as it did prior to my starting work on the alternator conversion. I agree with you about GR starter, that will be my next move if I have any hint of a problem going forward. For now, I am glad to have both cars back on the road. Thanks for the insight!

 

[RAC68]

Tony,

Yours is not a common situation as most have first switched to a Neg. Ground and retained their Generator (repolarized). After some period of time (with a Generator at Neg. ground) they then decide and install the Alternator. Since an alternator does not use magnetics to activate AC generation, the circuit polarity is not reinforced. However, a generator needs magnetic polarity to initiate charging and transmits power (amperage) in DC with a specific polarity.

Now, the starter can work with any polarity. However, using a DC polarization for a period of time, the brushes and other internal magnetically sensitive components takes on an orientation and performs best with that alignment. One thing a friend suggested is to switch brushes within the starter. If this change fixes the speed of the starter in the car, then your issue is polarity orientation of the brushes in the starter and he says you should be good to go. However, if this doesn't change starter cranking speed, then I would look to Michael's suggestion in that power is not being fully transmitted from the battery and you could have a bad or weak ground.

Keep in mind that 12.8 Volts (velocity) is a positive indicator but your starter also needs Amperage (flow) to create the torque/Power you require (Power=Amperage X Voltage) to turn the engine.

Again, good luck and all the best,
Ray(64BJ8P1)

 

[roscoe]

I put a reduction geared starter on a couple of years ago and reading this thread reminds me of how little I miss those times when I pushed the start button and heard rrrrrruh.......rrrrruuuuuhhhh and then nothing. True, it was usually a battery problem but the new starter does so much better with less than perfect voltage. My problem now is what to do with a car that gives me no excuses like, " oh, it wouldn't start this morning so I had to take the car with a great radio, airconditioning, comfortable seats, windshield wipers that can actually clean the windshield and usually comes back home with no issues that need attention". It uncannily starts ALL THE TIME so no excuses for not driving it.