Help with car diagnosis - clicks, won't turn

[Knottscott]

My son has a '97 Sunfire with ~ 147k miles. He installed a new battery Saturday and was told it was charged by Pep Boys. He only drove a little bit. Yesterday it just clicked and wouldn't turn over...wouldn't take a jump either. I haven't seen it yet, but am wondering if it's possible that the battery's just really weak. It has a new starter and new ignition switch too. My first guess is alternator but wanted to know if it could be a new battery that was never fully charged.

Any help is much appreciated!

[JimD]

I would charge the battery and try it. An inexpensive volt meter will tell you right away if the alternator is charging. If the voltage with the engine running does not go above about 13 volts (it should be 14-16 right after starting) then the alternator is bad. Places like Advance Auto will test the alternator for you.

It is also possible that the battery is bad. Before charging, pull the caps and make sure there is water in all the cells (it is not as obvious how to get the caps off on newer batteries but it has been possible on all I've tried). May daughter bought a battery and her car still wouldn't start (it did once or twice and then nothing). She was too timid to go back where she got the battery to ask what the problem was so I drove 150 miles (each way) to check it out. A hole had been poked in one cell and the water had drained out. I went back where she got it and they gave me a new one.

Jim

[Uncle Cracker]

Could be the battery, but I'll guess alternator, because the little bit he drove yesterday should've built the charge in the battery, but it didn't. The car was probably running on the battery alone during that time, and that's why it's dead now. Also, a bad alternator might be the reason you had to replace the battery in the first place. Easy enough to check... either put another battery in there, or if you can charge the battery enough to get it started, compare a voltmeter reading on the battery before and after the car starts. The reading should be one volt or so higher after the car starts, which would indicate the alternator is capable of putting energy back into the battery.

It is also possible you have a moderate short to ground somewhere in the electrical system, which drained the new battery down after he parked the car yesterday. This would also explain why the old battery needed replaced.

[SARGE..g-47]

Ditto Uncle Cracker....

[Knottscott]

Thanks gang!

[Daryl]

If it isn['t charging the alternator light will come on. I would wire brush the terminals and make sure there is a sound connection. Then take it back and have them check your charging system and battery.

[JimD]

The alternator light comes on when the field of the alternator has no current. If the connections to the alternator are good but it is not charging, the light will not come on.

Jim

[bfrikken]

I would also examine those cables real closely. I'm pretty sure it was a sunfire my brother was dealing with that was giving him the same fits. replaced batter and alternator, and starter, only to find that one of the cables needed to be replaced completely cause of bad connections to the alternator.

[jonmulzer]

Ground straps! Anytime after 100K if a vehicle starts having trouble starting or charging I first check the ground straps. They tend to rot away around this time and can cause all sorts of funny problems that are hard to diagnose. If the alternator checks out (they can check them out of the car at most chain auto stores) go ahead and buy a ground strap and replace it. If it is not the problem, it soon will be. It can also, sometimes, cause the battery to not charge without the light coming on. Your alternator grounds through the strap running from engine block to frame.

[Tom Slick]

clean the terminals and try it again. I've seen quite a few "clicks but wont start" caused by a poor connection at the terminals.

[mpc]

Quick/easy "is the battery worthwhile test" to try first... after the battery is re-charged:
1: turn the ignition key to the "ON" position. Don't try to start...
2: turn the headlights ON.
Are they nearly full bright? If so, the battery can spit out the full 12 volts at a half-way decent amount of current... leave the headlights on for 10 minutes. If they haven't dimmed appreciably, the battery is healthy. If they dim right away, the battery has "low capacity" - as if it were physically a small battery - and needs to be replaced.

Some cars have a "solenoid" physically attached to the starter; others use a remote solenoid. Most import cars have the solenoid on the starter; many American cars use a remote solenoid. The solenoid's job is to act as a relay (big ON-OFF switch) to convert the small electrical current from the ignition switch START position into the BIG current needed by the starter motor. The ignition key START position "picks" the solenoid which is just an electromagnet... the magnet part pulls on a big honkin' switch which then feeds the starter motor the 50 to 200 amps it requires.

Look at the battery "+" post (the one that often has the red rubber/plastic cover) and follow the half-inch thick wire. It'll either go to the starter motor - which means a starter motor mounted solenoid; or to a small round cylinder mounted almost anywhere under the hood - this is a remote solenoid setup; another fat wire will then continue to the starter motor.

For starter motor mounted solenoids, the solenoid has 2 functions:
1: a pair of electromagnet coils "slams" the gears from the starter motor itself into the flywheel ring gear (stick-shift cars) or torque converter ring gear (auto tranny cars). This "engages" the starter motor with the engine.
2: the solenoid, once the moving piston (the part that does the slamming) moves fully, closes an internal beefy switch to send power to the actual starter motor. This way, the starter motor isn't spinning until AFTER the gear teeth have meshed with the ring gear teeth.

For remote mounted solenoids:
1: it still has the 2 coils to "slam" the starter motor gear into the ring gear
2: it usually does NOT have the internal switch. Instead, the remote solenoid sends power to the motor (the half-inch thick wire) so the motor is actually spinning BEFORE the gears mesh with the engine ring gear - this means the teeth actually grind a bit as the gears engage.

What often happens is one of the two coils on starter-mounted solenoids goes bad... so the "slam" doesn't have the oomph needed to force the gears to mesh. On stick-shift cars, a simple test/fix is to put the car in 1st or reverse, release the parking brake and clutch pedal, and push the car forwards (1st gear) or backwards (reverse gear) a little bit. This slightly moves the engine/ring gear... maybe the teeth will line up better. Now turn the key to START and see if the starter works. If so, it's probably a weak solenoid. Sometimes that can be purchased separately from the starter motor... or just buy a whole remanufactured/rebuilt starter. Weak "slam" coils will make the "click" you hear come from the back of the engine/front of the transmission area since that's where the starter+solenoid are mounted.

On remote solenoids the motor should spin right away... so the gear meshing is often easier. You'll hear a grinding sound if the "slam" coils are weak. If you have a test light, or 12 volt multimeter, ground one end (black wire) to the battery "-" post and touch the red/test end to the output of the solenoid - the fat wire going to the starter. You should see light/+12volts while a helper turns the key to START if the solenoid is functioning. If so, the starter motor itself is probably bad.

As for the alternator:
The best way to test it is to remove it and take it to a chain auto parts store - most have starter testers and will do the test for free. A quickie go/no-go test though, if the engine will start/run, is to turn the headlights ON again... note how bright they are with the engine OFF. This is the "raw" +12volt brightness level. Now start the engine and see if the lights are brighter... if so, the alternator is working - it's generating 13 to 15 volts to recharge the battery. An alternator that charges though can still have problems: there are diodes (basically like one-way wires) that convert the alternator's AC voltage into DC to charge the battery. If one of those diodes shorts out (common) then only 2 of 3 phases will charge the battery (which is enough on most cars...) but that "dead" phase is SHORTING the battery when the engine is OFF. That'll discharge the battery overnight. The alternator tester at the parts store will catch this. A D-I-Y method is to:
1: have the battery fully charged
2: disconnect ALL wires at the "+" post.
3: Find the wire that goes to the alternator; it'll usually be the 2nd largest wire. Or you can find the wire mounted to the screw-stud on the back of the alternator instead.
4: Touch ONLY that wire to the battery (or to the stud - re-connect the battery end first) and see if you get sparks. If so, the alternator is DRAWING current from the battery and that's a sign of bad diodes.

If you can't identify the alternator output/charge wire, another way to do this test (and easier/safer if working with car electricity bugs you) is to use a test light or 12volt turn signal/dome light type of bulb. Disconnect ALL wires at the "+" post again. Close all car doors (no lights on anyplace), key OUT of the ignition, etc. Touch one end of the test light to the wires that go to the battery, and the other end to the battery "+" post. If the bulb glows (dimly or full bright) then something is drawing a lot of current - bad alternator/diodes, stuck light on inside the car (trunk light?), etc.

mpc