HOT alternator pulley

[Fearless1]

Put new serpentine belt on alternator, old one was separating. Pulley got extremely hot in 10 seconds with LOUD squealing. Have taken alternator out twice to test at two different auto parts stores. Alternator is good. Belt alignment is good. Pulleys on alternator and either side, A.I.R. and water pump are good. Unit was purchased last year, haven't taken a trip yet due to issues, so the problem may be preexisting. I put the old belt back on. There's a light squeal and the pulley still gets hot, but no ways as hot or as fast. Didn't run but about 20 seconds. Noticed that the new belt is a tad wider than the old one, but fits into the pulley groves nicely. Suggestions?

[legomybago]

Are the belts the same part #? Any bearing (gravel) noise at all on cold start up? Is it REALLY tight?

[Fearless1]

Belts are different makes and numbers. Also found part of an old belt in bottom of shroud with different number. TIGHT? Alternator spins freely. Can't detect any unusual noise on cold start up.

[legomybago]

I just wanted to make sure you had it really tight. You never know.....

Well it's either a pulley/bearing issue, or the wrong belt. If you search the forum, correct part numbers have been posted on this belt. If you go to Rock Auto, you may be able to cross reference the belt numbers you already have.

[Rickf1985]

If the battery is low the alternator will require a lot of power at first to charge the battery back up. Belt needs to be tight enough. Is it possible the pulley on the alternator is worn out from slipping in the past?

[Fearless1]

Belt is tight, about a 1/2" deflection. The alternator is new, last year. Battery was low 12.34. Will charge up battery and try again. I'll check for belt numbers also.

[Rickf1985]

What it boils down to is if it is squealing then the belt is slipping. This is only going to be caused by a few things, belt too loose, alternator pulley worn or alternator bearings bad. This is all assuming the belt is new and the correct belt which it sounds like you have covered.

[Fearless1]

Could a loose belt cause the pulley to get piping HOT in only a few seconds? Tomorrow I'll readjust the tension.

[M & J]

Absolutely a loose belt will cause the pulley to get hot. Does the pulley get hot before the alternator housing?

[Fearless1]

Yes, alternator housing is still cold - pulley piping HOT.

[Fearless1]

Wouldn't a loose belt have the same effect on the water pump and A.I.R. pulleys?

[shortbus]

Wouldn't a loose belt have the same effect on the water pump and A.I.R. pulleys?

A.I.R. or water pump wouldn't have quite the resistance as an alternator trying to push a high load.

[Rickf1985]

A.I.R. pump has almost zero load and water pump is very minimal. Alternator can take 5-10 horsepower  depending on amperage draw. That is a lot of power to transfer through that small pulley.

[Fearless1]

Thanks for the info guys. Adjusted belt tension, now it's tight as Dick's hat band. Much quieter and pulley doesn't seem to overheat. I was concerned about putting a great deal of tightness on it thinking the bearings might suffer. Now it's onto the big problem - engine overheating. Are we having fun yet? 

[legomybago]

Adjusted belt tension, now it's tight as Dick's hat band.

Hm?

[Fearless1]

You think maybe I should loosen it a little?

[M & J]

I think that analogy is as loose as forum rules allow........

[TerryH]

Definitely far tighter........

[legomybago]

You think maybe I should loosen it a little?

No, you want it tight....I just got a good laugh out of your "tight as a dicks hat band" comment

[lemortede]

Did you double check its routed correctly?
I have seen belts that looked to be routed correctly that were not.

[Fearless1]

Yes, I double checked the routing. At the start, I took a mental picture of the routing and with my "photographic memory" (sometimes clear as a picture, sometimes blank) I'm reasonably sure it's correct.