deflicted

I have the F23A4 ULEV 2.3L 4-cyl engine.

First thing I noticed (a few weeks ago) was that my engine belts were starting to squeal. Usually at night when leaving work, and in the morning. Revving the engine a little bit usually stops the squealing. I've also managed to stop the squealing once by turning off the headlights. Naturally, this made me think I might have an alternator going bad.

Then I started getting hard starts when the engine was cold. The engine sounded like it was turning over really slowly, but after a couple seconds it would start right up and drive great. So I figured maybe the battery was getting low. I thought I was really busy at work, so I hoped I could make it to the weekend so I'd have some time to check it out. Then one morning (maybe 2 days after the first hard start), it wouldn't turn at all. Completely dead. Jumped it with my wife's car and it started right up. Then I drove it straight to an auto parts store and bought a battery, knowing it was probably only a band-aid fix until the new battery went dead too.

Finally got a chance to check out the alternator today. Here's what I measured:

battery voltage with car not running: 12.5V
voltage across battery terminals while car idling: 14.4V
idling with headlights and A/C turned on: 14.3V
2000rpm with headlights and A/C on: 14.3V

So at this point I'm thinking maybe I guessed wrong and that the alternator isn't bad after all. Then the radiator fan relay clicked on, the RPM dropped noticeably, and the voltage across the battery terminals dropped to 12.5V.

Not sure what to think now. The alternator didn't flinch at the 2000rpm, headlights on, and A/C on, but the radiator fan drops it down almost 2 volts??? I'm no mechanic, but this didn't seem right to me. BTW, when the fan turns on, it appears to spin just fine, and I haven't had any overheating problems.

I pulled the alternator to see if it has bad bearings, but I'm not experienced enough to tell. The pulley doesn't spin as freely as the A/C compressor pulley does, but it's not really difficult to turn either. I hear a faint scraping sound when I turn it, but I'm not sure if that's bad bearings or just the normal sound of the brushes turning inside the coil.

Not sure what to check next. Does this sound like an alternator problem, or something else?

holmesnmanny

If the belt is squealing, you simply tighten up the belt. Simple as that. It's possible your belt is so old and brittle that even tightened up it doesn't have enough juice to not slip. The middle of the longest side of the belt should have about 90 degrees of maximum deflection(turning it with your thumb and index finger). Your voltage test shows a perfect working alternator.

It's possible you have two issues, loose belt and either a bad battery or a bad starter(wiggling the car causes the starter contacts or brushes to touch again, allowing for the starter to work).

The alternator is designed to charge in low output(12.6 volts) at idle and with no load, ac, or accessories on, when the car is fully warmed up(to save fuel). It's best to test on a completely cold start, so that the alternator is constantly putting out full voltage(running in full output mode, 14+ volts).

deflicted

Thanks for pointing out the fact that the alternator can operate at a lower voltage output. I wasn't aware of that at the time I did the test. Then I saw your comment, and learned about the ELD from some other threads. However, when I measured the 12.5V, it was at 2000rpm, with the headlights on, the A/C on, and the cooling fan had just clicked on. I heard the cooling fan relay, saw the fan start spinning, and then the voltage dropped to 12.5V. Wouldn't that be a situation where you'd expect the alternator to be operating at high output mode? I thought the point of the ELD was to turn the alternator off when you're not drawing much current, not to turn it off when you're drawing a ton of current.

m90polk1

If you battery is good and your belts are not an issue, have you alternator load tested. If it checks out fine you would want to look at your generator field control from the ecu, this controls alternator charging. Any fault in this circuit can cause the vehicle to not properly charge and display the issues you are having (besides squeaking belt).

holmesnmanny

Can you make a video ? Show everything from the tachometer dropping when the fan turns on, to the alternator output voltages at the various times. Let us see what's going on. Normally when the alternator is bad it will throw the charging light on.