2000 Expedition squealing and dimming lights

[Gage2502]

Ok so this happened twice now and only when its pouring rain. While driving my 2000 Expedition 5.4 I would hear a squealing sound coming from the engine bay and the lights would dim dash lights and every other lights I would have on.
Also it would seem like I would loose engine power...meaning that it would seem like the horsepower would drop..
So today when it happened I looked at the scan gauge and it showed about 10.8 volts.
This would happen for like 5 seconds and then it would stop and everything would be fine.
Any ideas????
Thanks

 

[EXPI2000]

Sounds like your alternator belt is slipping when it gets wet. When it is dry check and make sure it is good and tight and in goid condition. Itherwise I would say and try to avoid deep puddles when its raining hard.

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[toms89]

I agree. Check the belt and the belt tensioner. Maybe make sure no oil or coolant is leaking on the belt anywhere.

 

[mindgame]

+2 to the above.. chk Belt and tensioner...

 

[1997SCEBFEX]

+++ on above. recommendations.

PanHandler.

 

[Thermo]

Sounds like the tensioner is getting weak and is allowing the belt to slip. But, like the others said, if you have fluid on the belt, it can cause it to slip.

 

[K9JRF]

I would check belt tensioner and the belt as belt maybe worn and stretched .

 

[Gage2502]

Thanks everyone for the reply's. How often do you change the belt anyways? Every few years?
Also any difference in the Motorcraft or Goodyear belt?
Thanks