Alternator pulley getting really hot

[kristan]

I replaced an alternator/fan belt on my 3.2 engine that was about to give in.
After replacing and some spirited driving I noticed that the alternator pulley
is getting really hot (I can touch it for about 2 secs).
The alternator belt is tight, but has 5-10mm play.
I added one shim and it feels too loose (15mm)
It would wobble a bit when the engine is on.
When I turn the fan by hand the tight setup would turn the engine, while
the loose setup would not.
The fan itself turns freely, no grinding or getting stuck.

Here are a few more details:
- The alternator pulley has been chrome plated (not by me).
- The engine pulley is a non-AC pulley from a SC and has been bronze (?) plated
- The alternator light does not come on when the ignition is turned on, but the bulb is okay.

Is it normal that the pulley is much hotter than anything else surrounding it?
What else should I be checking?

Thanks

[wwest]

shorted alternator stator diode(s).

[kristan]

I guess an answer doesn't have to be long if it is correct.
Thanks Wwest!

[rick-l]

This would also discharge your battery with the key off.

[kristan]

Hmm,

I had to replace the battery not too long ago, but since then
it didn't seem to be a problem anymore.

[emac]

In my opinion that pulley would get hot with ie. engine heat and friction of the belt & pulley

[wwest]

Originally Posted by kristan

Hmm,

I had to replace the battery not too long ago, but since then
it didn't seem to be a problem anymore.

With a shorted battery cell the alternator/reg. would still try to charge the remaining 5 cells to 13.5 volts...one HOT alternator and evenually boiled away battery electrolyte.

[kristan]

A new voltage regulator is on its way here.
Anything else I should check before I put it in?

[dshepp806]

The alternator.

Doyle

[rick-l]

Seems to me you should have Mr Voltmeter and wrenches in hand and be doing some troubleshooting before buying new parts.

You have to figure these out tout suite

1. alternator hot
2. charge light off

When you disconnect the battery does it draw a lot of current?
Does the light flicker when you rev the engine?

[steely]

I think you should check the wiring on both sides of the indicator light.
The light works off battery power until the alternator starts charging.
The ckt is completed as it finds its path to ground via the alternator (when the alt is off).
There should be a diode in the light path to block the alternator power from getting to the battery side of the light when it does start charging. It should be behind the dash.

You have a 3.2 in an '81 (true?), so I don't know how your battery side of the light is wired.

The battery side of the light would normally get power from either the ign sw or the fuse panel (inst pnl fuse), or some combo of both, even depending on the 3.2 yr if stock, but in an 81 I don't know.
Any anti-theft stuff in your car (if in this ckt) may affect this too.

Find the diode and see if it is visibly bad/ connected.
Check continuity across it both ways to test it.

If that side if not wired properly, the light will never work.

If that side of the bulb wiring is ok, that would steer you to the alternator side.

Check the wiring to the alternator from this ckt (the indicator bulb) to see if it is even wired up.

Check your voltage level to see if in fact the alternator is charging.
Do not disconnect the battery if the engine is running.

I also think that if you are just talking about the pulley being hot (as compared to the surrounding area as you say), the belt friction can be a contributor if the slack isn't properly adjusted (or maybe even if it is).

Good luck and let us know how you are making out and if there are any other symptoms - and if you have a 3.2 in an 81.

[kristan]

As it turns out there was no connection between the alternator and the alternator light.
It went through an anti-theft device that I had long ago removed.

Now, the alternator light goes on when the ignition is on and goes
off when the engine is started.

Yesterday the battery was only charged 50% so I charged it overnight.
Today it hat 12.95V
At 1500rpm I get 14.2V with everything turned off.
I get 13.9V with blowers and radio on and
13.5V with the headlights on.
My charger says the alternator is charging at 97%

The car is a 1981 SC with a '89 Carrera 3.2l in it.
I checked behind the gauges but I could not find a diode.

Now I am basically back to square one. Is there a way to
check the alternator or voltage regulator myself?

[rick-l]

Define hot.

I would drive my 911 to work tomorrow and touch the pulley (maybe bring the meter and thermocouple) but it will be 106 degrees and the cab has no AC.

From your measurements I would say your alternator is working just fine.

[kristan]

As I said I can touch it for 2secs before getting too hot.
It is not like touching the exhaust and you get burned, but definitively hot.
I went beck to just one shim on the outside. That way the
belt vibrates a bit, but the play is still on 10mm.
We will see how that works.

[Joe Bob]

Do you have someone near you that has a pyrometer? Your version of hot may not be necessarily be a normal operating version of hot.....

Redheads are not hot to me.....

But your numbers sound normal.

[db_cooper]

Old school pryometer....if you put some water (spit) on it and it dances around..it is too hot.

If it slowly evaporates..its OK.

[kristan]

BTW: I tried the old school pyrometer and the water slowly evaporates.
Also, when I turn the fan, the engine doesn't crank (it used to).
I don't think my alternator belt is too tight.

Thanks.