I'm back after my last success with the old girl. I notices that it was running almost down in the red when I was driving it with only the radio on (A/C is out). I came home, popped the hood, and heard the alternator rattling. I tested the charge and was only getting aroung 10 on the meter (should be 14.5?). It is a new battery and alternator 5 months ago. Had the shop test the alternator and it came back good. I replaced the belt and put the alternator back on and it still was running down around 8 but the battery read 14.24. Now the needle is just below the middle but there is a huge draw with the lights or radio on, back down to 8. Could a bearing in the alternator cause it to put out a weak charge or do they just totally die?

 

If the alternator tested good, then suggest to inspect your cables and connections - particularly the large ones, including the ground cables.

Didn't catch your model year, by my era had a problem with the connector going into the alternator - used to get a new connector to splice in with each new alternator.

Have had occurences where the cable corrodes near the connectors, but underneath the insulation not visible until a bit of insulation is opened up.

Also consider that the dash voltmeter may not be correct - when mine seems low, first thing is to sharply rap a couple of times on the top of the dash, usually the voltmeter pops right to where it should be. Thinking it's due to a poor connection between the voltmeter and the flexible circuit sheet used on the instrument panel. For me, beatin' on stuff is easier than fixing it. :-)

As far as your alternator rattling - this is not good, even though it may have tested good. Just a matter of time before failure - suggest being only 5 months old, may be able to make a valid warranty claim.

Good luck, and keep us posted.

 

if your picture is your truck, mine looks just like it. 1989 with a 4.9 liter in it. Runs like crazy but little stuff keeps popping up. The joys of 20+ year old vehicles. thanks for the info.

 

i have recently looked at a 98 f150 4x4 with the 4.6 and the dealer had to put an alternator on it. well he just got a used one from a junk yard and it now makes a whining noise as soon as you start it and does not go away after warm up but it is charging just fine. i just wanted to know what it could be