Alternator problem

fleehillfarm · Nov 3, 2018

A while back I accidentally reversed the polarity when putting the battery back on my 1968 International 275. The wire from the alternator to the solenoid completely burnt out. I have remade the wire and put on a new battery and the tractor starts and runs ok but there is no red light coming on when you turn the ignition key. Does the fact that the tractor starts mean that the alternator hasn't been damaged or is it the case that I have to wait and see whether the battery runs down as it isn't charging. Thanks for any guidance.

rustcollector · Nov 3, 2018

Possible that you burned out the bulb when polarity was reversed? Bulb should not know reverse polarity, but if a short to ground occurred through the path, possible? Get a good volt meter and check the battery voltage with the tractor running. Over 12 volts dc and you are fine.

timcasbolt · Nov 3, 2018

(quoted from post at 13:38:43 11/03/18) A while back I accidentally reversed the polarity when putting the battery back on my 1968 International 275. The wire from the alternator to the solenoid completely burnt out. I have remade the wire and put on a new battery and the tractor starts and runs ok but there is no red light coming on when you turn the ignition key. Does the fact that the tractor starts mean that the alternator hasn't been damaged or is it the case that I have to wait and see whether the battery runs down as it isn't charging. Thanks for any guidance.

You could put a voltmeter on the battery before starting to measure the available battery voltage, then measure the battery voltage again after the engine is running. It's typical to see a battery at around 12.5, but after starting it should be closer to 14 volts.
You can buy an inexpensive voltmeter at almost any variety store, hardware store or auto parts store. I've seen them for 99 cents with coupon at Harbor Freight.

fleehillfarm · Nov 3, 2018

Thanks for the advice guys. I'll have a rummage in the garage to find my multimeter and check the voltage while its running.

Geo-TH,In · Nov 3, 2018

All the auto parts store in my town will test alternators for
free.

Mike(NEOhio) · Nov 3, 2018

If there's no voltage to the battery when it's running you could have fried the rectifier diodes along with the wire. Easy fix if that's the problem.

mite-help · Nov 3, 2018

reverse polarity usually means instant alt. damage.

old · Nov 3, 2018

The moment you hooked up the battery backwards you let the smoke out of the alternator and it has fried. You have about a .001% chance it is still good

fleehillfarm · Nov 3, 2018

I don't think they test alternators for free around here. I'm actually in Cornwall, England. If it has fried the diodes where are they and is it easy to remedy? Thanks.

Bob M · Nov 3, 2018

Virtually certain the alternator is fried. Probably also the regulator - no matter whether internal or external. Thus the non-functioning idiot light.

Steve@Advance · Nov 3, 2018

Do you know what brand/model the alternator is?

Over here the Delco 10SI is the most common and popular alternator. So common it is cheaper and much easier to just trade it in for a rebuilt one.

Your situation may be different. Diodes are not too difficult to replace, but some require soldering. They may have to be ordered online or from a rebuilder.

timcasbolt · Nov 3, 2018

(quoted from post at 01:52:50 11/04/18) Do you know what brand/model the alternator is?

Over here the Delco 10SI is the most common and popular alternator. So common it is cheaper and much easier to just trade it in for a rebuilt one.

Your situation may be different. Diodes are not too difficult to replace, but some require soldering. They may have to be ordered online or from a rebuilder.

You can usually find a kit (probably online) that includes a regulator, brushes, bushings, and a diode trio. Maybe 10 bucks last I looked.

timcasbolt · Nov 3, 2018

Correction: I don't think they use bushings, and bearings aren't usually needed.

fleehillfarm · Nov 4, 2018

You were right guys. Just put a multi-meter across the new battery and it registered 12.6v. Started the tractor and it still registered 12.6. Took off the alternator and removed the black end cover and the wires inside were all black and crispy. Everything burnt out. Time to but a new alternator. Does anybody know if anything else will be damaged such as the solenoid etc. Thanks again guys

timcasbolt · Nov 4, 2018

(quoted from post at 13:25:36 11/04/18) You were right guys. Just put a multi-meter across the new battery and it registered 12.6v. Started the tractor and it still registered 12.6. Took off the alternator and removed the black end cover and the wires inside were all black and crispy. Everything burnt out. Time to but a new alternator. Does anybody know if anything else will be damaged such as the solenoid etc. Thanks again guys

If the alternator has the internal regulator, that should be everything that needs to be replaced.

fleehillfarm · Nov 4, 2018

The alternator is a ALT 114. I found some on ebay and they do have an internal regulator so hopefully I should be ok with just a new alternator. £57 not too bad

:roll:

fleehillfarm · Nov 4, 2018

The alternator is an ALT 114 which has an internal voltage regulator so I should be ok with just a new alternator. £57 could be worse.

Alternator problem

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