Guys, need your help with my 1978 Z. I am having a problem where I will drive it around town for a while, park it, come back out a few min later and she won't even turn over. Turning the key gets nothing, no clicking, no crank, nothing. All the lights/acces/ work fine and do not dim but the only thing I can do is jump the battery and away it goes. I have replaced the ignition switch, ignition rod, numerous batteries, alternator and am still at a loss at to what is going on. The battery is not drained while running (i have both an in car Volt and Amp meter) showing the battery at around 12 V running and slightly + on the amp gage. Its almost like there is a short somewhere but why would it be overcome by a jump to the battery? Its getting to a point where I can't take the car anywhere at the risk of being stranded! Thanks in advance for all of your help.

 

It can be the infamous hot solenoid problem where heat of the engine heats up the solenoid so it doesn't conduct enough current (especially if it has an internal problem) when you try to crank it hot. Not cranking, but lights being good is a classic symptom. A new solenoid or heat shielding, especially if you have headers, can fix it.

12v running is too low, is the gage accurate? Should be more like 13.5 running. You need a multimeter to check the voltage at the output stud of the alternator. With the engine running, put the negative lead on the battery -, the positive lead on the stud. Note the voltage. If the voltage isn't around 13.5, ground to battery could be bad, your replacement alternator could be bad, or the excitor voltage to it could be missing. That comes into one of the small terminals on the alternator. It originates at the key switch, goes thru the idiot lamp on the instrument panel, then goes to alternator. It's purpose is to excite the internal regulator of the alternator so alternator starts producing current.


If the voltage is ok at the output stud, put the positive lead on the battery +. There should be a fraction of a volt difference from what it read at the alternator stud. If it's too much of a voltage difference (voltage drop), there is resistance somewhere between the alternator and the battery. Check the positive & negative wires/cables. I'm sure you've cleaned the battery connections, but there can be problems where the negative cable attaches to the block, in one of the battery cable crimps, etc. I've also seen on cars where the alternator output goes to a terminal block on the radiator support first for distribution, and that connection is corroded or the crimps there are bad.

Could also be a combination of both problems. If your car was an automatic I'd say might also be a neutral/safety switch, but don't know if those year 4 speed Camaros have them.

edit: just noticed you said you had an ammeter. I don't like those cause they add resistance to the charge line (especially if you don't solder the connections), don't tell you much more than you get from the voltmeter, and if that 10 gage wire you ran to the ammeter ever shorts somewhere (like where it went thru the firewall) you will get a nasty electrical fire cause there is no fuse to pop. JMO

 

Angel- thanks for the reply, yeah went back out with my multimeter and had 12V with battery sitting car off, 14 V at battery when running and 14V at alternator post while running. Good point about the heat, I do have headers and the starter sits so close I can't imagine it not being affected by the heat. Any idea how jumping the battery would overcome the solenoid? (not really familiar with electrical functionality). Rechecked the gage inside the car (V meter) and it was reading around 14 while running, point takenn about the ammeter (I didn't put it in originally but will check to make sure no problems) Thanks again for the help.

 

Maybe jumping it just added enough extra to get it over the point where it would kick in. Or placing the clamps on your cables changed something mechanically enough for it to pass more current. e.g. my GFs daughter was having intermittent no start problems on her Nissan. But it would start immediately when jumped.

I checked the cable terminals 1st. They have a spacer that fits at the pinch point of the clamp. Spacer keeps from over tightening & breaking the terminal. With wear, the terminal for the negative no longer clmaped the battery post tightly, it was just snug. Good enough most of the time. Being slightly loose also allowed for heat buildup from the resistance at the post/terminal contact point. That resulted in a thin layer of crust.

So I cleaned the post & terminal, removed the spacer and thinned it. Thinning allowed more clamping force. I couldn't remove it entirely cause the terminal is really flimsy brass, and no spacer would have busted it b4 enough tension could be put on the nut so it wouldn't loosen.

You just have to check for piddly stuff like that, cause nay slight resistance anywhere can be the problem. Or a combination of slight problems, especially the seldom cleaned ground cable to block connection point.