radiator cap/alternator - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Sinister · 08-14-2002, 07:38 PM

uhhhh, weird subject, i thought i'd kill 2 birds with 1 stone...
which radiator cap do y'all recommend? (i.e. how many pounds), just remembered the one i got is outta a scrap yard...
and lastly, shouldn't my battery read more than the 12 or so volts when the alternator is charging?
tried the screwdriver in the back deal, even took it down to autozone to get checked, supposed to be all right...
jumped the F and #3 terminal to see if i got more juice but it's only about 12 volts...

Longhorn Man · 08-14-2002, 07:49 PM

12 volts...it's dead.

*Zkast* · 08-14-2002, 07:49 PM

Most of these old trucks take a 13-16lb cap. If you have known weak spots in your cooling system stay with a lower lb rating.
The lower the cap rating the safer it is on old componants but water boiles at a lower temp when the pressure is lower.

Externaly regulated alternator should be 13.0v or so at idle. Amperage should be about 20-25 at idle with a load. Anything off idle should increase dramticly ( 13.5v @ 55A or higher)

Use a voltmeter and check the alternator output wire and at the battery to get an accurate reading.
If the alternator is weak and you have to replace it, I'd suggest going with an internal regulator unit... No more dim headlights and slow wipers at idle!

Sinister · 08-14-2002, 08:07 PM

damn and i just got this way cool battery charger...

hey Zkast, which wire coming out of the alternator?
is it the F terminal blue?wire?
12 volts outta all of them anyway...
can i still run factory ammeter with 1 wire alt.?
and what's a good one to get?
hey, longhornmail how's the caddy project going?

*Zkast* · 08-14-2002, 08:12 PM

Ill have to go out an look at my wiring.. cant remember right off hand how I did it lol. Yes it uses the factory ammeter and wiring.
I didnt go with the 1 wire setup.. I used parts of the original wiring to energize it.

If your at 12v, like longhorn said.. ITS DEAD lol.

Sinister · 08-14-2002, 08:24 PM

thanks guys...
time to bite the bullet...
i used to live in lawrence, hanging at the bottleneck, etc.
beautiful out that way...

08-14-2002, 07:38 PM	#1
Sinister Between Trucks... Join Date: Mar 2002 Location: Los Angeles, CA. Posts: 3,830	radiator cap/alternator uhhhh, weird subject, i thought i'd kill 2 birds with 1 stone... which radiator cap do y'all recommend? (i.e. how many pounds), just remembered the one i got is outta a scrap yard... and lastly, shouldn't my battery read more than the 12 or so volts when the alternator is charging? tried the screwdriver in the back deal, even took it down to autozone to get checked, supposed to be all right... jumped the F and #3 terminal to see if i got more juice but it's only about 12 volts... __________________ Beat it to fit, Paint it to match...

08-14-2002, 08:07 PM	#4
Sinister Between Trucks... Join Date: Mar 2002 Location: Los Angeles, CA. Posts: 3,830	damn and i just got this way cool battery charger... hey Zkast, which wire coming out of the alternator? is it the F terminal blue?wire? 12 volts outta all of them anyway... can i still run factory ammeter with 1 wire alt.? and what's a good one to get? hey, longhornmail how's the caddy project going? __________________ Beat it to fit, Paint it to match...

08-14-2002, 08:24 PM	#6
Sinister Between Trucks... Join Date: Mar 2002 Location: Los Angeles, CA. Posts: 3,830	thanks guys... time to bite the bullet... i used to live in lawrence, hanging at the bottleneck, etc. beautiful out that way... __________________ Beat it to fit, Paint it to match...

08-14-2002, 07:49 PM	#2
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,693	12 volts...it's dead.

08-14-2002, 07:49 PM	#3
Zkast Account Suspended Join Date: May 2002 Location: Olathe, Kansas Posts: 929	Most of these old trucks take a 13-16lb cap. If you have known weak spots in your cooling system stay with a lower lb rating. The lower the cap rating the safer it is on old componants but water boiles at a lower temp when the pressure is lower. Externaly regulated alternator should be 13.0v or so at idle. Amperage should be about 20-25 at idle with a load. Anything off idle should increase dramticly ( 13.5v @ 55A or higher) Use a voltmeter and check the alternator output wire and at the battery to get an accurate reading. If the alternator is weak and you have to replace it, I'd suggest going with an internal regulator unit... No more dim headlights and slow wipers at idle!

08-14-2002, 08:12 PM	#5
Zkast Account Suspended Join Date: May 2002 Location: Olathe, Kansas Posts: 929	Ill have to go out an look at my wiring.. cant remember right off hand how I did it lol. Yes it uses the factory ammeter and wiring. I didnt go with the 1 wire setup.. I used parts of the original wiring to energize it. If your at 12v, like longhorn said.. ITS DEAD lol.



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