Secondly a couple of comments on getting the alternator off a rev 3 turbo as there seems to be a lot of variation between different revisions.
> Taking the bracket off and bringing it up the OSR of the engine bay failed because one of the bolts holding the bracket on is obscured by the drive shaft. Even if you could get it off i would question whether it would squeeze out anyway. > Sliding it along from the OSR to NSR of the engine bay is a right pain. After taking out the airbox, charcoal canister, fuse box, speed sensor and numerous other little bits it got stuck next to the coolant expansion tank. I started taking this off and then realised it was also going to be a swine to get out as the ECU loom was in the way. I gave up and put everything back.> Dropping the subframe may have worked but without my hoist the car was jacked up from the subframe. > Taking out the exhaust centre section is another option. After looking at the state of some of the nuts on my exhaust i couldn't be bothered. > Removing the OS axle worked a treat and doesn't actually take very long at all although draining and refilling the box is a pain because everything has to be nice and clean. This is what i did in the end.Prior to taking the alternator out i tested the 3 wires with the ignition on.
All had battery voltage wrt. to ground expect one which was a fraction of a volt under, maybe because of the voltage drop across the indicator light or something. I measured the output voltage from the main terminal with the engine running which was between 10 and 12V depending on the load, obviously not high enough.After getting it out i've found a shorted diode in the rectifier and another with a large forward drop.
Immediately prior to the alternator failing I noticed smoke in the engine bay. My theory is the shorted diode caused the alternator to heat up, burning oil and other crap on it causing the smoke. The case was very hot after a short run time.I also tested the coils, everything else seems ok.
The bottom line is i could have unscrewed the rectifier from under the car saving the mission of getting it off and refitting it. Infact it would have been possible to run all the tests in the BGB without taking it off.I hope this helps someone!
