New alternator and new regulator charging at 17.5 V

[Jerry/MT]

My alternator warning light came on a couple of weeks ago. I checked the base battery voltage (engine off 12.5V) and then started the tractor and measured the voltage (12.5 V). I replaced the factory alternator on my '82 Ford 4610 and decided to replace the voltage regulator also. I installed the new voltage regulator on the new alternator and ran the same voltage check. Engine off I got 12.5V and engine running I got 17.5 V. The voltage regulator was supposedly adjustable but when I tried adjusting it, it stayed at 17.5 V. I suspect the voltage regulator is bad It is a Transpo M5-152A, the same as the one that was on my old alternator and the regulated voltage should be 14.2V. When installed originally, the old alternator ran at 14.2 V with old voltage regulator.
Is there any reason that the new alternator would not be regulated to 14.2 V ?

 

[ROUSTABOUT]

When a regulator is bad it doesn't regulate. Alternator will put out 17.5 volts without a regulator to regulate it.

 

[Roadworthy]

Either your wiring is messed up and lacks a ground reference, you left out a wire somewhere, or the regulator is defective. You could even try your old regulator on the new alternator just for comparison.

 

[Jerry/MT]

Either your wiring is messed up and lacks a ground reference, you left out a wire somewhere, or the regulator is defective. You could even try your old regulator on the new alternator just for comparison.

I did that and got the same result. The field wire connection tab is loose so I am thinking it was damaged in shipping. I checked the grounds and they were good. I checked the resistance of the battery to alternator connection un-hooked at it was less than 0.1 ohms.

 

[Jerry/MT]

When a regulator is bad it doesn't regulate. Alternator will put out 17.5 volts without a regulator to regulate it.

Yeah if the regulator fails it goes to full field. I put a new regulator on a new alternator and it runs at 17.5 V,. I put the old VR on the new alternator with the same effect. That's why I am suspecting the alternator.

 

[Roadworthy]

Just because a part is new does not mean it's good.

 

[Jerry/MT]

My alternator warning light came on a couple of weeks ago. I checked the base battery voltage (engine off 12.5V) and then started the tractor and measured the voltage (12.5 V). I replaced the factory alternator on my '82 Ford 4610 and decided to replace the voltage regulator also. I installed the new voltage regulator on the new alternator and ran the same voltage check. Engine off I got 12.5V and engine running I got 17.5 V. The voltage regulator was supposedly adjustable but when I tried adjusting it, it stayed at 17.5 V. I suspect the voltage regulator is bad It is a Transpo M5-152A, the same as the one that was on my old alternator and the regulated voltage should be 14.2V. When installed originally, the old alternator ran at 14.2 V with old voltage regulator.
Is there any reason that the new alternator would not be regulated to 14.2 V ?

Thanks for all the help. I sent the alternator back to Amazon.