hi chaps, i have been getting a strange whirring noise from my alternator, it`s not there all the time at first but gets worse the longer the engine is running. when the noise happens my volt meter needle goes up to full and when it stops it goes back down to between 12/13v.
this afternoon i done some testing using my digital volt meter, i connected the meter to the battery and was getting 13v with the engine running, when the whirring noise from my alternator started i was getting 16.7v at the battery and when the noise ceased it went back down to 13v.
my alternator seems to be wired up wierd, this is how it is wired.
i have one wire going to the nut terminal on the rear of the alternator which goes round the engine bay and in to the loom over on the drivers side. there is a white connector with two wires coming from it, one red and one white this plugs into the side of the alternator. the red wire goes to the same nut terminal on the rear as the other wire and the white is not connected but has some sort of device built in line on it.
i tested, while the engine was running,the two spade connectors in the alternator on the side where the red and white wires connect to using the white plug. on the spade which the red wire would connect to i got no volts and on the other which the white wire would connect i got 0.05v.
by this time the whirring noise coming from the alternator was constant and pumping 16v into the battery. i pulled the white plug out of the alternator so the red and white wires are not connected to the alternator, the noise has now stopped and i am getting 12.5v at the battery.
does this make any sence, do i leave the white plug pulled out, what is this connection for? the device that is wired in line on the white wire has the following label attached and reads.... INGERSOL RAND 120403-025,V#18558,59732305 002.
i recently had to replace the module and coil on my hei distributor and was told that the alternator pushing out 16v could have been the reason why they failed.

my engine is a 1970`s 350 small block fitted in a 1950 3100 truck.

i am now confused as to what to do next and worried to drive the truck in case i break down, at least the alternator isn`t cooking my brand new battery anymore.
has anyone got any advise that could help me out here?

bill.

 

Is it an alternator, or generator. If it is a true 1970, it must have an external voltage regulator. If the alternator has been upgraded, it could have an internal voltage regulator. That red wire without seeing it, is a reference wire to the internal regulator. If it does have an external regulator replace it, if it is an internal replace the alternator. Look for something like this on the firewall, that http://imageshack.us/a/img818/5903/120920006.jpg

 

i think it must have been upgraded, i have no external regulator so it looks like a new alternator is required. thanks for your help.
bill.

 

[QUOTE=bass2112;227262]i think it must have been upgraded, i have no external regulator so it looks like a new alternator is required. thanks for your help.
bill.[/QUOT

Went n got new alternator just fitted it and all is good no noise and 14v at the batt. I must say though it is wired funny but it's working.