Alternator getting hot - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Chevy nutcase · 08-29-2023, 07:25 PM

Was farting around rebuilding the carb on my 66 c10 today and I have 2 questions. One, did these 250s come with an alternator or generator? If originally a generator then the PO switched it to an alternator. My second question would be after a cold start and running for barely 5 minutes, should it get hot enough it's just past the point where it's too hot to touch? One other thing I might add is the battery was half dead for this so maybe it was just working hard? Idk

**Chevy Fleetside** · 08-29-2023, 08:27 PM

yeah I had that problem when I had an electric fan and amps for the stereo on my truck. Actually burned up an alternator and had to replace in on the road. I upgraded to a one wire 100 amp Alt and all was fine after.

**cwcarpenter98** · 08-29-2023, 11:24 PM

GM switched to using alternators on the sixes and v8s in 63. They kept the generator words on the instrument cluster for some reason though.

Re-charging the battery could cause some excess heat. What definitely will cause it to get hot is if you have too much resistance somewhere in the wiring. I had some heavy resistance when turning on the a/c that was wired through the fuse block. Switched the wiring to run relays to power the a/c and my excess resistance went away. No more charging issues for me.

**1971 GMC SHORTY** · 08-30-2023, 12:54 AM

You wed To see What Amps Your Fans Drawing and Then see alternator OutPut You Can a find 100 Amp Alternators champion champion raider with fan radiator radiator Fans Pull 10-20 Amps

Chevy nutcase · 08-30-2023, 08:04 AM

Quote:

Originally Posted by cwcarpenter98

GM switched to using alternators on the sixes and v8s in 63. They kept the generator words on the instrument cluster for some reason though.

Re-charging the battery could cause some excess heat. What definitely will cause it to get hot is if you have too much resistance somewhere in the wiring. I had some heavy resistance when turning on the a/c that was wired through the fuse block. Switched the wiring to run relays to power the a/c and my excess resistance went away. No more charging issues for me.

I'm hoping it was the burden of a half dead battery causing the heat as I don't have a/c or electric fans. Truck is bone stock and even the AM radio was off.

Agv63 · 08-30-2023, 08:47 AM

Most probably because of state of battery. Alternators do run hot as it charges, And at idle, alt is turning faster compared to crank but the fan for cooling is only doing so much, wil have more air movement internally when it speeds up.

When battery is fully charged it can be monitored and verified if still running too hot.

08-29-2023, 07:25 PM	#1
Chevy nutcase Registered User Join Date: Mar 2021 Location: Hershey Pennsylvania Posts: 339	Alternator getting hot Was farting around rebuilding the carb on my 66 c10 today and I have 2 questions. One, did these 250s come with an alternator or generator? If originally a generator then the PO switched it to an alternator. My second question would be after a cold start and running for barely 5 minutes, should it get hot enough it's just past the point where it's too hot to touch? One other thing I might add is the battery was half dead for this so maybe it was just working hard? Idk

08-29-2023, 08:27 PM	#2
Chevy Fleetside Registered User Join Date: Sep 2006 Location: San Francisco Posts: 4,782	Re: Alternator getting hot yeah I had that problem when I had an electric fan and amps for the stereo on my truck. Actually burned up an alternator and had to replace in on the road. I upgraded to a one wire 100 amp Alt and all was fine after. __________________ "A man and his truck, what a beautiful thing" 65 Short Fleetside BBC 65 Long Fleetside 283 3 on the tree for now. my build thread http://www.67-72chevytrucks.com/vboa...d.php?t=259536

08-29-2023, 11:24 PM	#3
cwcarpenter98 Senior Member Join Date: Jan 2018 Location: Hickory Flat, GA Posts: 4,491	Re: Alternator getting hot GM switched to using alternators on the sixes and v8s in 63. They kept the generator words on the instrument cluster for some reason though. Re-charging the battery could cause some excess heat. What definitely will cause it to get hot is if you have too much resistance somewhere in the wiring. I had some heavy resistance when turning on the a/c that was wired through the fuse block. Switched the wiring to run relays to power the a/c and my excess resistance went away. No more charging issues for me. __________________ Christian Carpenter 1963 C10 - Frankentruck 283, Muncie 3 speed with overdrive Overdrive wiring here 1963-ish truck bed trailer - Half-Wit 1981 C10 - Penny 305, th350 --> Soon to be 350, Saginaw 4 speed 1995 Dodge Dakota Sport "I'll put it simple: if you're going hard enough left, you'll find yourself turning right." - Doc Hudson

08-30-2023, 12:54 AM	#4
1971 GMC SHORTY Senior Member Join Date: Apr 2009 Location: SAN FERNANDO VALLE SOL CAL Posts: 1,064	Re: Alternator getting hot You wed To see What Amps Your Fans Drawing and Then see alternator OutPut You Can a find 100 Amp Alternators champion champion raider with fan radiator radiator Fans Pull 10-20 Amps __________________ 1966 GMC K25 V6 351E Original Utility Truck 2000 C3500 Hot Rod Utility Truck 2003 ROAD KING 100th 124ci 6 Speed 145CI M/P Pro Street FXR 2002 FXDP 2007 2500HD DURAMAX. DD Studio Teamsters / Mechanic Retired GM Master Tech 20 Years Retired Ford Tech 15 Years

08-30-2023, 08:47 AM	#6
Agv63 Registered User Join Date: Jan 2023 Location: Johannesburg South africa. Posts: 78	Re: Alternator getting hot Most probably because of state of battery. Alternators do run hot as it charges, And at idle, alt is turning faster compared to crank but the fan for cooling is only doing so much, wil have more air movement internally when it speeds up. When battery is fully charged it can be monitored and verified if still running too hot.

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