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I've got a 2000 7.3...Runs like a top. Today however, I noticed that the battery light came on. It didn't come on and stay on, it flickered. When I put my foot on the gas, it went off. When I let off, it came on, but not steadily. There was no rhythm to it. If you looked at the volt meter, it never came off 14/15 volts. Could it be the alternator going? Any help much appreciated.
When is the last time the serpentine belt and/or tensioner was replaced? If the belt is not tight enough and slipping some, an alternator might not charge properly. There is a wear indicator on the tensioner that should tell you if it is good or not.
Even thought this tensioner is for the 5.0/5.8 Ford, the 7.3 would have similar markings on tensioner.
Tips:
1. Buy a decent Volt/Ohm meter say at Sears. Read the voltage while its running at the battery. Should be between ~14.2 volts DC. +/- .5 volts.
2. Load test the battery with a load tester. If it fails replace it. Doesn't require battery removal, does require a good quality load tester with clean battery cables and battery posts (Good load tester is ~50-80 bucks).
3. Load test the alternator (requires removal and a trip to a good rebuild house of higher end parts store). Could have a shorted or week diode bridge.
4. The battery cables (both) need to be inspected. Both ends should be disassembled treated with battery cleaner, wire brushed, reassembled then sprayed with battery protector. This is a maintenance/service item that should be performed every so often versus waiting for trouble.
5 While your down at the starter cleaning its connections it's not a bad time to pull it and have it bench tested as well. if it has a ton of miles on it rebuild it.
Ok, as for the belt and the tensioner, I don't know when they had last been changed. I've had the truck for just over a year now. I tried to check the tensioner, and I couldn't make out any markings on it. It's a pig to get to being that it's behind the coolant reservoir. The belt looks like it's in good condition. No shiny spots or rough edges.
Used the volt meter, twice. The first time was 12.6. The second was 11.7. I know for a fact that when I put the new batteries in only a few months ago, that they were at 14.4, bc I checked them then.
I think I will take out the alternator and take it to the local rebuild guy. Bit of a ball ache, as it's my work truck. That, and I'm in the UK and getting parts can be a bit of a pig. Makes me miss home, and how easy it was to get stuff at the local parts store. Looks like I know what I'm doing tomorrow!
I appreciate the help. If you can think of anything else, I would love to hear your two cents.
Just wanted to say thank you to everyone for the help. Turns out the alternator was gone after 215,000k. Brushes were pretty much non-existent. All back up and running again. Thanks guys!
TB
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