GS300 - Bad alternator?

[Ompa 8]

Hi!

I purchased a 2008 GS300 about two months ago and so far I'm very pleased with my purchase. However, a couple of days ago my car died on me and left me stranded on an airport (not very fun).

What happened was that the "Check Charging System" as well as the "Battery Warning" came on when on idle, and after turning the car off (stupid) it wouldn't start again. I bought a new Battery since the one installed was the one that came with the car originally, and voilá the problem went away. However today the same issue emerged with the new Battery.

Scenario: When turned off the Battery read 12.0 V. Starting it and keeping it at idle made the "Check Charging System" light go on. Revving the car made it go away though.

As of writing this I'm charging my new Battery, but with a feeling that my alternator might have gone bad? I presume that I still should be getting 14+V at idle if my alternator would be working correctly?

 

And if the issue would be the alternator - is this a job that could be recommended as a DIY? I replace my oil, filters and the occasional brake caliper by myself but have never changed an GS300 alternator before. (it looks quite tight down there in the engine bay...).

Thanks in advance!

Best Regards

Chris from Sweden

 

[JeffL 91]

Bump

 

 

[MNP 15]

I've had a whine for months now and it got worse in the cold weather until the charge light came on...bad alternator which my local garage has replaced.  Just been for a trip to Manchester airport having got the car back on Tuesday...no whine.  Will post again when I've paid the bill.  She was booked in for a service and MoT anyway, she passed with no advisories.  Hope that's an end to big bills!!  Mark.

[Britprius 1,413]

Apart from the assesability problem changing the alternator is reasonably simple. Take a note or photo of how the drive belt is fitted, and it is a good idea to change this at the same time if there are any doubts as to how old or worn it is.

John.

[MNP 15]

Well I've just paid my bill for MoT, short service, new alternator.  £597.  It would have been a lot more at Lexus!!  

[Herbie 1,716]

1 hour ago, MNP said:

Well I've just paid my bill for MoT, short service, new alternator.  £597.  It would have been a lot more at Lexus!!  

Indeed it would, but anyone who would take an 11-year old car to a main dealers for work like that needs their head wobbling anyway.

[m4rkw 392]

On 12/6/2019 at 11:42 PM, Ompa said:

Scenario: When turned off the battery read 12.0 V. Starting it and keeping it at idle made the "Check Charging System" light go on. Revving the car made it go away though.

As of writing this I'm charging my new battery, but with a feeling that my alternator might have gone bad? I presume that I still should be getting 14+V at idle if my alternator would be working correctly?

You've probably already done something about it now but you should always diagnose the problem correctly first before replacing parts. Sure it could be the alternator but there's probably 50-100 other things that could produce the same symptoms. If you throw parts at a car without a diagnosis you'll tend to run out of money before you run out of guesses.

[Ompa 8]

An update:

After charging the Battery I put it in the car again and it started without any issues. However - I only got about 12.6V at idle, so clearly I had a charging issue. Revving the car made the voltage increase though, but not to desired levels. I therefore ordered a new alternator from Germany, but after waiting a couple of days I got a message from the seller that it was no longer in stock. So i decided to buy one at Lexus instead, and also paid them to change it for me (I currently have no garage and the weather here in Sweden was not "outdoor-mechanic-friendly"). This set me back £590, but the car now works perfectly.

 

For future readers: This video was excellent in describing the process of changing the alternator:

 

[Initial P 23]

I had mine go early last September paid £350 for a Denso part similar problem to those listed above all been good since but I do have a cig lighter volt meter so I can always check its working.

My Indy said he could fit a aftermarket one for around £200.

[Herbie 1,716]

Have you people never heard of refurbishing your own alternator or going for an exchange refurb unit?

There's only a few parts to an alternator so they don't take much to fix. Things like the voltage regulator and rectifier are usually self-contained units that you just swap over so they're easy to do yourself. If it's bearings or coils then that's when you go for an exchange unit if you haven't got the resources to sort them out.

Much cheaper way of doing it and much better for the environment instead of buying new and scrapping the old.

[johnatg 388]

+1 to that - spot on.

[Britprius 1,413]

About the only thing that cannot be changed simply by the home mechanic on an alternator is the coil winding's. The Bearings are usually standard off the shelf parts available from bearing suppliers for pennies. However bearings do not usually cause charging problems unless they have got to the point where the rotor will no longer turn.
Often the slip ring brushes are the problem with one brush wearing down while the other has lots of life left. This is because many designs use a brush that sits on or near the centre of rotation that wares very little while the other brush runs on a ring about 1" in diameter meaning for every rotation of the  rotor it rubs on the ring for over 3". Swapping the brushes over with a little stretch of the spring on the worn brush will restore operation for as much time again.

John.

[rock on 81]

I had my mk2 aristo alty refurbished for 200 replacement one was pricey

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