heloo!!!!!! i put in a new alternator and voltage regulator in my 77 250 comet, but the alt light stays on and the headlights are way dim. no problem starting yet. short somewhere? i have some loose wires hangin around!!!! also haven't cured the knock and rattle, been looking at rebuildts, for around $1200. anybody have any suggestions? what would a fair price be to pay a mechanic for labor? thanksssssssss!!!!!!!!!!!!!!!!!!
There was no mention (that I read) about the battery status (new/old/tested good, etc.,)?? To easily test the battery, crank the engine, let if run for a few seconds then turn it off and repeat the cranking 'session' for about 6-8 times. If the engine still cranks, the problem indicates it probably isn't the battery (check the loose wires you mentioned for a short to ground. Even so - terminate those ends so that do not contact ground in the future). To test the alternator (and yes, one can buy a defective one), crank the engine let it warm for 3-4 minutes. Disconnect the positve terminal (while the engine is running) from the battery. If the engine continues to run, the alt is probably okay (meaning it is providing a positive charge to the battery). If not, take the alternator back to the auto parts store and let them test it. One can also determine if an alternator is bad by reading the voltage at the battery terminals. Using a cheapy volt/ohm meter, record the voltage reading (across battery terminals) with the engine off. The meter should read 12V or slightly above. Then ceck the voltage AFTER cranking the engine and letting it idle (around 800 rpms minium). The voltage should read higher than 12V (=>13 volts) while the engine is running. Most places like Autozone or similar can check for alternator or battery problems without taking everything off the car. I'd go to one of those places to help determine the cause then take the necessary actions (new battery, replace the new alt, etc). Good Luck, Rick p.s. knock and rattle - need more specific info