While driving about 50 mph on the freeway last week, my battery light came on. Then the oil pressure light followed and the whole car felt like it shut off. I pressed and released on the clutch and pressed on the accelerator and fortunately manage to get the car running again. Only to shut off again seconds later. I still had momentum so I continued to cruise until I could pull over to the side of the road. (Not a comfortable feeling when you lose power steering either)
I managed to restart the car and drive off but had to detour straight for the nearest local auto parts store. The alternator and the battery were both suspects. So I bought one of each.
Before I began to work on my car, I wanted to make sure my alternator was the culprit. Here's how I checked:
1. Measured the voltage across the battery terminals with a multi-meter while the car was off. It measured about 12.28 - not too bad. Anything lower than 12 volts would mean I would need to recharge the battery with my plug-in outlet charger.
2. Started the car.
3. Measured the voltage across the battery terminals with a multi-meter while the car was running. It measured about 12.75. It should have been a little bit higher if the alternator was truly charging.
4. To confirm, I had another person press on the accelerator until 2500 RPM was reached.
5. Measured the voltage across the battery terminals with a multi-meter while the car ran at 2500 RPM. It measured about 12.75 - not good. An alternator running at 2500 RPM should have brought the voltage up to 13.5 - 15.1 volts. I was convinced my alternator needed to be replaced.
I didn't think changing the alternator would take me 2 days to fix; but now I know what to watch out for - making sure I use the right socket size to avoid stripping the bottom nut (Inconveniently located).
Here's how I replaced my alternator for repairs:
1. Disconnected the battery (negative cable first, positive cable last)
2. Unscrewed the bolt holding the white ground cable.
3. Detached the wiring harness from the alternator.
4. Loosened and removed the alternator adjustment bolt. Kept a mark on the original position of the alternator adjustment bolt.
5. Removed the screw for the wire harness support.
6. Lifted the driver's side of the car onto jacks with a wooden block behind the back wheel for added support.
7. Removed the lug nuts and the wheel.
8. Removed the screws to the splash-guard to get better access to the alternator.
9. Removed the through bolt nut. This is where I had lots of trouble. Fortunately, a socket designed to remove stripped nuts saved my day.
10. Positioned the alternator enough to get the alternator belt off of the pulley.
11. Removed the 2 bolts holding the bottom bracket to the engine block.
12. Positioned and slid the old alternator out from the bottom.
13. Tested the gap clearance on the bracket for the new alternator. Hammered the spacer in the bracket until the alternator could slide easily in between the bracket.
14. Installed the new alternator. Positioned and slid the new alternator in from the bottom.
15. Secured the 2 bracket bolts back at 33 lbs.ft torque.
16. Slid the alternator belt around the pulley and secured the bottom through bolt (but not tighten).
17. Reconnected all the wires including the wire harness support onto the new alternator.
18. Inserted the adjustment bolt and tightened at it's original position.
19. Tightened the bottom through bolt to 33 lbs.ft torque.
20. Returned and screwed the splash guard back in place.
21. Reconnected the battery (positive first, negative last)
Now the same simple alternator test will determine if all is well. Started the engine, ran the RPM up to 2500, and checked the voltage across the battery terminals. 14.5 volts! Perfect!