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05 Forester XS Manual
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Discussion Starter · #1 ·
So recently my crank pulley separated, throwing the AC and alternator/power steering belts off. I replaced the pulley, but I don't seem to be getting full power out of the alternator. Car died in town yesterday, jump started and had to keep it in high rpm to get it home (it was a KM away thankfully.) Boosted the batter back to 14V... think I'll probably replace the alternator. Currently running at idle, I read 13V across the battery, I think it should be 14.2V?

My Q is, I used some penetrating oil on the alternator adjusting screw (it was pretty rusty) and can't 100% say some spray didn't get on the alternator pulley.... could this be causing the alternator to slip some, and not provide full power? I think belt tension is good - had a tiny squeal going around a round about in town before it died.

Battery very likely was run down after the crank pulley separated but it seems to have charged back up well, it's a few years old.
 

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05 Forester XS Manual
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Discussion Starter · #3 ·
Yeah... Annoying thing is I just bought a new belt for this job! :p I do get that if it's fouled, that's the end of it.
 

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Discussion Starter · #5 ·
I'll try tightening it a little more, but I tightened it to that guideline.
 

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2007 Forester Sports XT 4EAT
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I wouldn't make it too tight, as that will stress the pulley bearings. If it's just a touch of oil, it could wear off. :confused:

Just had a thought. Make sure the alternator pivot bolt is tight, as that helps ground the alternator to the engine.

Bobby...

['07 FSXT MODding Journal] ['03 X MODding Journal]
 

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2007 2.5XT Limited 4EAT
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[Currently running at idle, I read 13V across the battery, I think it should be 14.2V?]

13V at idle sounds about right. You are not likely to see over 14V unless the alternator is full fielding under load. You could try turning on the a/c, headlights, rear defrost, and all of the other electrical loads in the vehicle and then take your reading across the battery posts. This will give you a very good idea of how the alternator is performing. I would start here as its an easy test.

If you are not seeing 14+ volts with the alternator under full load, you could have a bad alternator. Could be you got some lube on the pulley and it was slipping. Or perhaps the belt isn't quite tight enough. Those jack screws that control the tension on the belt can be finicky.
 

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05 Forester XS Manual
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311 Posts
Discussion Starter · #8 ·
Update! :banana::banana:

I tightened the alternator tensioner a tiny bit more, now I'm getting 14.2V on start up!!!!
 
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