Alternator Question

[jsa]

Hi, I drive a 1991 5.0L F150. My alternator was dead so I just replaced it today. I put on a brand new belt too.

4 questions, any answers appreciated

1. Is the alternator supposed to get really hot? After I drove home I couldn't touch it.

2. Is a new belt supposed to be a lot tighter? (my tension arm is almost all the way up)

3. Is it normal for a new alternator to give off a strange odor. It smells sort of like plastic burning but the smell isn't very strong. I'm assuming that it is a little sticker that I left on the side of it melting, and I just removed that.

4. Should all of the wheels that the belt connects to be able to turn freely by hand when the belt is removed?

[pind]

1. no, it should not get that hot. It might get warm, but shold not burn your hand to touch it.

2. unless the belt is on wrong, or the alternator has the wrong pulley on it, the belt should not be any tighter. I would think it may be routed improperly

3. new alternators can give off odd odors, but if it continues for more than a couple days, check it out.

4. The idler, tensioner, a/c compressor, p/s pump, water pump, and alternator should turn by hand, the crank pulley should not.

[jsa]

Well the alternator still does get too hot to touch, and the belt is noticably tighter than the original one. I went to discount and told them which truck I had and this is the belt they gave me. I dont get any funny smells anymore and the battery is charging fine. Should I be worried?

[ModMech]

The alternators will get VERY hot under high loads, like running the A/C etc., but should not get TOO hot under "normal" driving.

If your alternator gets VERY hot under "normal" driving, be sure to check the battery. The most common cause of alternator failure is a bad battery. A shorted battery may start the vehicle, but it will also place a HUGE load on the alternator, almost continually. Therefore, the Alt will "melt down" due to excessive output and heat, similar to your symptoms.

You can easily check your own battery for this problem by measuring the voltage after it's sat overnight. It should be 12.60-12.72 Vdc, anything less suggests a bad battery (one or more cells).

[jsa]

I initially replaced the battery before I replaced the alternator. The brand new battery of course ended up running down because it was the alternator all along. After I replaced the alternator the brand new battery was still dead. I jumped the battery and drove around for a bit. So I am assuming now after reading the information that you just gave me that the new alternator is probably getting hot because it is still trying to charge up the battery as well as run the AC, radio, headlights, or whatever other loads I have on it. Once the battery is charged up it shouldn't get so hot. Right?