GL Class (X164) 2007-2012: GL320CDI, GL420CDI, GL450, GL550

Voltage Regulator Replacement

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Old Dec 3, 2022 | 05:35 PM
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2008 GL 320 CDI
Voltage Regulator Replacement

Hi All, it's time to replace the voltage regulator in my 2008 GL320. Has anyone been able to do this without removing the alternator form the car ? Since it's about 10 degrees outside I have to wait to get it to a heated space and I'm just wondering how much frustration I have to look forward to. Thanks, Will
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Old Dec 4, 2022 | 09:54 AM
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This is an odd question. How do you know the regulator needs to be replaced? I do not recall a single instance of someone needing to replace the regulator.

It bolts right on to the back of the alternator, and is on the upper portion of the rear.

That is, assuming the alternator is the same between the gas and diesel engines.
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Old Dec 5, 2022 | 06:14 PM
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I think you can tell by looking whether you have access to do the job.

Eric's note is pretty relevant I think ... any time I replaced just the regulator, I soon needed to replace the rest of the alternator.
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Old Dec 6, 2022 | 07:25 PM
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2008 GL 320 CDI
The regulators wear out. The brushes on the reg wear down the same as motor brushes wear down and need replacing at 100,000 miles or so. I posed the question because it's winter here in Alaska and I want to make sure I have the needed tools with me when I get it to the shop where I'll be able to complete the work. Also trying to figure the time needed to complete the job. Thanks guys
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Old Dec 6, 2022 | 08:00 PM
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2008 gl320
Might be doable but doesn't look easy. Here's a picture looking up at the back of the alternator from just behind the steering rack.

This is from my 08 gl320 with the 180 amp valeo alternator. The main lug is at like 12 o'clock so it's probably not easy to get off without taking the alternator off.

If you have the 220 amp alternator it would probably be easier. The lug is out towards the passenger side. Not sure what vehicles have the 220 amp though.



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Old Dec 7, 2022 | 06:11 AM
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The brushes wear out, but so do the contacts on the shaft.

What is the voltage?

I would just change the whole alternator. It would probably be quicker than trying to unbolt the regulator in that confined space. Get a good rebuilt.

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Old Dec 10, 2022 | 07:11 PM
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I've been able to get the car up on a rack since I first posted and yeah, at the very least the alternator would probably need to be unbolted to even have a chance at the regulator and by the time I'm that deep into it a new alternator probably makes more sense. Nice picture by the way, that is my setup to a T. Thanks for the input guys, Will
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Old Dec 11, 2022 | 09:40 AM
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Originally Posted by audioneurotica
I've been able to get the car up on a rack since I first posted
tfw no rack available
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