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Hi Guys,

 

Can anyone give a step by step on replacing an alternator on 2005 Porsche cayenne S?

 

Symptom is weak start in cold weather. Battery just replaced with recommended replacement from Porsche Dealer(cost $250)

 

Thanks for your time,

Mike

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Hi Guys,

 

Can anyone give a step by step on replacing an alternator on 2005 Porsche cayenne S?

 

Symptom is weak start in cold weather. Battery just replaced with recommended replacement from Porsche Dealer(cost $250)

 

Thanks for your time,

Mike

 

What tests have you done to isolate the problem to the alternator?  It is a pretty pricey item to replace if it is not the source of your issues.

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replacing battery is the only thing i have done.. Not sure what other items would cause a weak startup other than battery or alternator not charging battery. Any help would be gratefully appreciated.

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To add to what JFP said this is a minimum 3 hour job (more like 5 hours if you have never done it before) that requires draining the coolant and refilling as well as drive belt, and several engine/wheel covers.

Draining and refilling the coolant requires a vacuum tool to remove air from the system. If you do not have the tools and time then have a good Porsche shop quote you price.

 

So make sure you have a bad alternator before tackling this.

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replacing battery is the only thing i have done.. Not sure what other items would cause a weak startup other than battery or alternator not charging battery. Any help would be gratefully appreciated.

 

At a minimum, you should be testing the alternators' output voltage at idle; it should be between 13.5 and 14.5 volts.  A more ideal test would be to load test the unit to see how it responds to the electrical system demands, but that requires a special tool to accomplish.  You could also have primary cable problems, which can easily cause this type of issue, and also requires testing to evaluate.

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As i remember the alternator of a cayenne s is not water cooled. I think this feature comes only with the turbo.

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replacing battery is the only thing i have done.. Not sure what other items would cause a weak startup other than battery or alternator not charging battery. Any help would be gratefully appreciated.

 

At a minimum, you should be testing the alternators' output voltage at idle; it should be between 13.5 and 14.5 volts.  A more ideal test would be to load test the unit to see how it responds to the electrical system demands, but that requires a special tool to accomplish.  You could also have primary cable problems, which can easily cause this type of issue, and also requires testing to evaluate.

 

Actually - with the dash mounted voltmeter - it's pretty easy to see if it's the alternator or not. 

 

Check idle voltage - needle should be right around 14V (plus/minus a bit), rev the engine, it should increase perhaps 0.5V. Turn on heavy loads - parking lights, inner high beams (if you have HIDs), rear defroster. At idle the voltage should still exceed 13.5V, at 2,000 RPM I'd expect to see closer to 14V with that load.

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