Re: 67 L79 stalls after 20 minutes
It's saying the charging system, by way of the voltage regulator is 'seeing' the battery to be dead as a door nail! This may or may not be true. V-reg could be seeing things that "ain't" due to faulty oxidized/corroded connection(s), V-reg could faulty, Etc.
But, another clue given in the original post was the 'shop reported'.... So, if the car's in the shop under care/supervision of a paid 'expert', what the heck are we doing responding to the post with remote guestimate/diagnosis?????
Shop mechanics should be earning their pay buy making sure the battery is fully charged before running alternator output analysis. Also, a number of references in this thread were made to 'the condensor'. There are a myraid of capacitors in the system, three specifically associated with 'funnies' in this area:
(1) Condensor across points inside the dist cap.
(2) Radio RF capacitor across coil to ground (if no TI).
(3) Radio RF capacitor across V-Reg to ground.
If any of these are electrically marginal (leaking internally), then as they pass leakage current they'll heat up and avalanche to passing more and more current. Those associated with the ignition process itself (points and radio coil), WILL show up like a sore thumb when the shop 'pro' puts the car on an engine analyzer and watches the ignition waveform over time....
That's why it takes TWO measurements to assess the health of a capacitor: (1) measure the specific charge storage capacity (capacitance in fractional Farads), AND (2) measure the component's dissipation factor (when charging voltage source is removed, how much charge remains stored in the device after a brief time interval). Caps can test A-OK in #1 but be leaking like a sieve in test #2. Dissipation factor is expressed in percentage and readings of 1-5% are considered normal/good for most caps. Dissipation factors above 10% begin to indict the component's internal integrity....
Few auto repair shops have the 'digi-bridge' test equipment to check energy storage electrical components (coils, caps). They tend to troubleshoot by rote component substitution. But, watching the spark waveform on an engine analyzer tells enough to find/stone the problem(s)....
It's saying the charging system, by way of the voltage regulator is 'seeing' the battery to be dead as a door nail! This may or may not be true. V-reg could be seeing things that "ain't" due to faulty oxidized/corroded connection(s), V-reg could faulty, Etc.
But, another clue given in the original post was the 'shop reported'.... So, if the car's in the shop under care/supervision of a paid 'expert', what the heck are we doing responding to the post with remote guestimate/diagnosis?????
Shop mechanics should be earning their pay buy making sure the battery is fully charged before running alternator output analysis. Also, a number of references in this thread were made to 'the condensor'. There are a myraid of capacitors in the system, three specifically associated with 'funnies' in this area:
(1) Condensor across points inside the dist cap.
(2) Radio RF capacitor across coil to ground (if no TI).
(3) Radio RF capacitor across V-Reg to ground.
If any of these are electrically marginal (leaking internally), then as they pass leakage current they'll heat up and avalanche to passing more and more current. Those associated with the ignition process itself (points and radio coil), WILL show up like a sore thumb when the shop 'pro' puts the car on an engine analyzer and watches the ignition waveform over time....
That's why it takes TWO measurements to assess the health of a capacitor: (1) measure the specific charge storage capacity (capacitance in fractional Farads), AND (2) measure the component's dissipation factor (when charging voltage source is removed, how much charge remains stored in the device after a brief time interval). Caps can test A-OK in #1 but be leaking like a sieve in test #2. Dissipation factor is expressed in percentage and readings of 1-5% are considered normal/good for most caps. Dissipation factors above 10% begin to indict the component's internal integrity....
Few auto repair shops have the 'digi-bridge' test equipment to check energy storage electrical components (coils, caps). They tend to troubleshoot by rote component substitution. But, watching the spark waveform on an engine analyzer tells enough to find/stone the problem(s)....
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