Bad Battery? Alternator?

[pontiacgp]

No rear defog, and blow motor is toast. No heat. Only thing that runs is my radio and my gauges (3 pd, volts, oil, temp, and tach). All wired correctly. Radio stuff is all stock 33 year old GM. Even the speakers. Sounds like sh*t.

Edit: I have noticed, that when the radio is ON, but turned all the way down, sometimes I hear static.

is the gauge reading correct?. What is the volts reading in a multimeter at the battery with the engine at idle? Also does the engine have a good ground?

 

[MrSony]

is the gauge reading correct?. What is the volts reading in a multimeter at the battery with the engine at idle? Also does the engine have a good ground?

Last time I checked, at idle, the battery was 14v at idle. Grounds are good, only one I'm sketchy about is the bellhousing to firewall. The screw is kinda stripped in the hole. It holds, but doesn't tighten. The ground ain't at risk of falling off, but it could be more secure. If anything, that I think would be the problem. How many grounds should there be, in a stock application? there's the battery ground, the bellhousing to firewall... ?

 

[1bad79]

2.6" according to my digital calipers, probably closer to 2.5, 2.6 seems like an odd size. Measured on the face of it, don't know if it matters.
I never had a problem with this before. The alternator also sat on a shelf from Feb '17 to last November, but it's a mostly clean single car garage.

Ok that sounds like it’s in the ballpark I just ran across a lot of larger size pulleys lately when getting after market alternators for forklifts not all gm ones either and same issues your having so I swapped pulleys to slightly smaller ones so it spins a little faster and that has solved my issues

 

[pontiacgp]

Last time I checked, at idle, the battery was 14v at idle. Grounds are good, only one I'm sketchy about is the bellhousing to firewall. The screw is kinda stripped in the hole. It holds, but doesn't tighten. The ground ain't at risk of falling off, but it could be more secure. If anything, that I think would be the problem. How many grounds should there be, in a stock application? there's the battery ground, the bellhousing to firewall... ?

was that 14v reading with the car in gear and did you use a multimeter to check it?

 

[MrSony]

was that 14v reading with the car in gear and did you use a multimeter to check it?

Read it in park, yes used a multimeter.

 

[fleming442]

Unless it's creating a problem, I wouldn't worry about it. Most alternators won't be full amperage output at idle. If you need to, get a bigger unit.

 

[pontiacgp]

Read it in park, yes used a multimeter.

you posted your problem is when you have it in drive and at idle so I would have the parking brake on and something to block the tires if you don't have help and test it with the multimeter when it it's in gear.

 

[MrSony]

you posted your problem is when you have it in drive and at idle so I would have the parking brake on and something to block the tires if you don't have help and test it with the multimeter when it it's in gear.

Don't know if it was clear, but this also happens in park. Just when it's idling low, it sometimes will only read about 12 volts, i give it some gas, the lights get brighter and it goes to 14.5ish on the gauge and it's fine. it usually happens when they car is cold, like first start of the day. after it gets some heat in it it usually doesn't do it.

 

[pontiacgp]

Don't know if it was clear, but this also happens in park. Just when it's idling low, it sometimes will only read about 12 volts, i give it some gas, the lights get brighter and it goes to 14.5ish on the gauge and it's fine. it usually happens when they car is cold, like first start of the day. after it gets some heat in it it usually doesn't do it.

then why didn't you test it when the car is first started cold

 

[MrSony]

then why didn't you test it when the car is first started cold

Car was already running trying to get the choke to operate correctly and at op temp and acting normally. It comes and goes. Haven't been driving it all that much, just within a mile or two of the house. I'll get a meter on it tomorrow if I can.