since then, I've gone through two brush/regulator units, and two batteries... all normal I suppose.

anyway, this old 90A alternator is starting to have some loud bearing noise, and I'm getting fluctuations in my voltage reading at idle, and its also no longer able to produce 13-14V with the lights on, let alone having the radio and heater on at the same time as the lights... I dunno for sure why this is, but my guess is the copper on the rotating assy has worn down so much over the years, that it just cannot do the job any more, and now the bearings are going (hence the noise?)...

SO, I had a close look at this 90A on my scirocco, and compared it to some old 78A chevy alternators I have laying around. The alternator housings are the same, but the way the wiring connects is different.

My question: can I use a chevy alternator in a VW?

I should be able to swap the pulleys, but is there any reason to believe it won't work? assuming I decifer how to wire it up properly??? I'm not the best at electrics, so I figured I'd ask the experts...

Modified by pheengurs at 11:53 AM 11-7-2009

Volts is volts, but thats a lot of "what if's".

You can fit a 120A alt (cant remember from what)

BMW E30

iPura Vida!

'werd scho wida'

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88 Scirocco GT 16V, LP7Y, glass sunroof, non A/C model

member since 6/2005

'couve approved √

I've had to wire up a separate switch for the wiper washer, as I couldn't get the origial on the column to work.

P.O. wired up a switch for under the bumper fog lights. When the lights burned out, I removed them, and capped the grounds.

before the alt swap, I had a fuel pump die on me. during the diagnostic process I screwed up one of the tests shown in the bently, and fried my ignition switch and wiring all the way to the fuse box. it also melted the fuse box in some areas. It took me a long time, but I replaced all wiring that was burned, and cleaned up the fuse box as best I could. Ended up replacing the fuel pump relay, and outer fuel pump, ignition module, and assorted wiring. All have worked without fail until this year.

the only other electrical issue I've noticed is sometimes the fuel pump relay gets jolted loose. I'll have to push on it, and then you can hear the relay click in, and the fuel pump run... The roads here in Calgary are terrible, and sometimes those potholes are unavoidable.

I know the melted fuse box thing sounds bad, but I was very diligent, and careful in fixing it. I've just recently been able to get my hands on a pristine fuse box from another junked scirocco in Saskatoon, so I'll probably install it this winter...

anyway, so you're saying I've got a big electrical problem then? going through brushes and batteries. It's only in the last two years really, that I've noticed the voltage issue. And that's because I've now got myself a job, where I have to park the car outside all year round, including the winter. My work is at the airport, so the wind there is worse due to all the open space, etc.. I keep it plugged in, but the plugs are on the cheapo company timer, 10 mins out of every 60...which doesn't help much in minus 40!!!

as you can see, I do go on my point being, winters have been especially brutal on this car in the last few years, whereas before, I always had a job with heated, underground parking, or another vehicle to drive in winter. so at first I just thought it was winter destroying my batteries, and the brush/regulator replacements were just a result of the alt having to give a deeper charge to the batt...

so if yall have any suggestions I'm game...

on a good note, I was able to score another VW 90 amp from a jetta here in Calgary pickyerpart. It's got the same pulley length & size etc (though it's easy enough to swap pulleys) so I'm gonna swap that in, hopefully this weekend, and see what happens...

I inadvertently fried the original volt gauge a couple of years ago doing some re-wiring. It always showed that the car was making only 12.5 volts at best without lights or heater fan on. The heater fan on high would drop it down to 10-11v on the gauge. A digital voltmeter always showed (at the alternator) an output of around 14v and lights were bright, so I wasn't that concerned.

So, after I bought and installed a new gauge.. an instant +2 volts appeared throughout the range. Just a thought.

After I changed out my positive and negative battery wires and the wires including the blue exciter wire to the alternator my car starts a lot better.

Got VAG-COM? I do.

more cow bell

Replace all your power lines from Alt to Battery etc.
Replace all your grounds as well.
Work the problems, one step at a time. Don't get frustrated, but be persistent.

Do it right and you'll be driving soon with out all the bugs. Ignore the advice and possibly end up with a burned out hulk. Not a nice yard ornament

I use these "Adjustable" VR on ALL my Sciroccos....I then adjust it to 14.5V at the battery terminals w/ engine running @ 3000 RPM

'couve approved √

Me too please!