Alterator Maintenance and replacement

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jimmyh
Joined: Fri 18 Mar, 2016 23:55
Posts: 7

  Z3 roadster 2.8

Alterator Maintenance and replacement

Post by jimmyh » Mon 23 Sep, 2019 00:33

Hi All

Not sure if the right place to put this.

This last week my Z3 failed me. In particular the alternator failed.
This taught me a few valuable lessons.

Most importantly that it is a maintenance item. Due to what i consider a dumb design there is an air scoop from the bottom of the front bumper that funnels air into the back of the alternator. So far as I can see there is no filter meaning road crap gets scooped up and blown into the plastic shroud at on the back of the alternator which in turn blocks it up and causes short circuits across the unit etc.

The shroud is easy enough to remove and I think can "probably" be removed without the alternator being removed. Its held on with three 10mm bolts if i remember correctly. I would recommend removing the shroud and checking for debris every 6 - 12 months depending on use (especially autumn and winter when there will be a lot of leaf debris).

Second removing the alternator is a piece of cake HOWEVER beware the plastic raditor overflow pipe across the top of the air box. It is VERY brittle over time and pretty much crumbles at the lightest touch and is £35 from BMW.

Replacing the laternator is relatively easy however make sure you have some form of small pry bar to lever it around once in place to get the lower bolt in. Also lower bolt is the longer of the two bolts.

Finally. If the alternator fails when out and about the car will still run for a fair while. I managed to drive from Bisley back home to Kent with no alternator and 50% of that time i had to have my headlights on. Not smart in retrospect as having had my waterpump fail in the past if the belt comes off the pulleys while the engine is running it destroys EVERYTHING forward of the block fan, radiator shroud and radiator. In total a belt off is around £500 in repair bills.

Point is in a pich car will run without alternator.

LaRy
Joined: Mon 12 Nov, 2018 17:47
Posts: 50

  Z3 roadster 2.8

Re: Alterator Maintenance and replacement

Post by LaRy » Mon 23 Sep, 2019 07:50

You wrote:
Most importantly that it is a maintenance item. Due to what i consider a dumb design there is an air scoop from the bottom of the front bumper that funnels air into the back of the alternator. So far as I can see there is no filter meaning road crap gets scooped up and blown into the plastic shroud at on the back of the alternator which in turn blocks it up and causes short circuits across the unit etc.

My alternator was also broken for the same reason. Anyway, I agree that the change is easy. Also that the belt tensioner has a smart hole, making it possible to lock the tensioner in a position with loose belt, by putting a rod though the hole.
Beware of another thing, at the same time I changed the belt tensioner. My car has one of those using an inside spring. Some of those has a very low quality, squeaking from the tension mechanism even as brand new and making a poor job.

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colb
Joined: Sat 05 May, 2012 23:46
Posts: 663

  Z3 roadster 1.8 TU
Location: Newport South Wales UK

Re: Alterator Maintenance and replacement

Post by colb » Mon 23 Sep, 2019 10:04

My alternator failed on me, the inbuilt regulator went duff only letting it give out 12v instead of the usual 14v, car was ok with day driving but use of headlights resulted in flat battery next day. Fitted a new alternator and decided to fit a volt meter to monitor the output for the future. First I used a voltmeter that plugged into the cig lighter, one of these https://www.ebay.co.uk/itm/12V-24V-LED- ... SwkqxdgfhN
Then decided to fit a permenant volt meter with usb sockets in one of the blank switch positions in the centre console.
https://www.ebay.co.uk/p/Universal-Dual ... 2400874514
I used the power feed from the 12v cig lighter to power the unit which is ignition fed so switches off when the ignition is off.
If you don't have a spare switch position and have space you could fit a round shape version like this one
https://www.ebay.co.uk/itm/Car-Boat-12V ... Sw36tc-g8K
Finished install
Image
Colb
1999 BMW 1.8 Z3
1998 Honda Deauville NT650V

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