I also had to replace the alternator on the '85 2M4 yesterday (what fun!!). I have a few pointers for others on this matter so here goes:
Once I had figured out the jigsaw puzzle - it took me about 45 minutes to get the old alternator out and put the new one in (not including oil change time).
From: Peter Frise
From: Sketch
Minor additions to removing the alternator: one does not need to raise the car to loosen the adjustment bolt on the lower side of the alternator--with the car parked and on my back, I could reach in quite easily with a ratchet and a socket between splash shield and control arm (depending on how long your drivebelt is there may be a clearance problem with a brake line--use wrench instead). For the upper (pivot) bolt, I removed the aluminium vent tube for the alternator to gain some more room (heat shield left on, dog-bone and alternator brackets untouched). It's nice to be able to sit in the trunk whilst working on the engine! Alternator comes out on the bottom, after electrical connectors have been removed (press in tab with needle-nose pliers to release catch), heat shield on. For re-installation leaving the heat shield off is easier. Tightening the (new) belt was easiest by using a long wrench, placing it between alternator bracket and alternator, and holding up the belt tension by propping up the wrench with a big screw driver against the trunk wall.
Of all the removal suggestions I've seen, this one seems to involve the _least_ pain: no raising the car, no disconnecting dog bones (the vent tube comes out very easily), no removing brackets et al.
From: Nikolaj Peddie-Richers
Alternator removal on the 88 V6 is the same for both the 5-speed AND auto. Remove the RR tire, disconnect battery, remove 2 elec. connectors to alternator, remove top bolt of alternator mount [15mm], remove adj. bolt [13mm], belt, drop alternator out the bottom rear between the suspension components. No need to remove anything else!
From: Paul Vargyas
When re-hanging the alternator on the V6, that top bolt is a bit of a pain to get started. I found that the following helps quite a bit:
BTW...I like to pull the right rear wheel...it is NOT "necessary" to do so, but makes access a lot easier, especially if you are on a "creeper" and have to roll around under the car.
From: Alan Ritter
PEP Boys sells a generic kit for Delco alternators. It contains new brushes, front sealed bearing (you just grease the rear needle bearings) and a new regulator. The whole thing takes very little time. If your alternator is broken, you can go to an alternator shop and buy any part you need. I recently rebuilt my wife's alternator (same one as the 4-cyl uses). The cost was $32 for a new field winding which had a broken wire (it's the large coil that fits against the case) and $15 for the rebuild kit. That $47 rather than $49.95 for a 1-year warranty, rebuild, generic, who-knows-where-it-was-built piece of ...
I prefer not to remove and reinstall the alternator in a few months because it was not correctly rebuilt in the first place. Remember, I was repairing a bad alternator. Of maybe 10 or 12 alternators I have rebuild this was the first time I had to replace that coil (stator). With out that part, the price is $15. The kit contains a new regulator module and that or the brushes is where the problems usually locate. What do you think about 20 minutes work (4 long screws, 6 small nuts, and one large nut) and saving $35 for your efforts?
From: Lee Brown
For a first-timer like me, it took quite a bit more time than the 20 minutes suggested by Lee Brown. I have no doubt that he can do it, but my humble self couldn't match this. The big nut on the pulley can be on very tight. Having just picked up the rebuild kit and new belts, I had the right Allen key and a breaker bar, but no suitable wrench for the big nut. Two adjustable wrenches didn't do much except mar the nut and get me agitated. Plan ahead for that 15/16" wrench and breaker bar...
One of the four bolts holding the two halves of the casing together torqued off--drilled it out and replaced it with a longer bolt and a nut at the end. I'm sure I could have re-tapped the hole, but didn't have the approrpiate tool and then you end up with the same problem: a steel bolt in a cast aluminum housing (or some such thing). There was white powder on the three bolts that came out, product of electrolysis.
Keep the various spacers in their proper order and do one step at a time, following the instructions in the rebuild kit. I spent a bit of time sanding off corrosion on terminals and putting on a bit of silicone spray where I thought it would help keep connectors corrosion-free for a bit.
The rebuild kit from Canadian Tire ($20CDN, about $14US) did not include the rear needle bearing. I tore my alternator apart because it had a bad bearing. It was the rear one--picked one up for very little at an alternator rebuild shop. These alternators are very common. If you re-use your rear bearing, make sure none of the rollers are scored. If the bearing goes bad on you, the whole alternator has to be torn apart again (getting quite good at it by this point ;-). Use the green wheel bearing grease for re-greasing, but don't put in too much, because it'll prevent the rotor from sliding in all the way (this one had me stumped for a bit when I couldn't reassemble the housing).
From: Nikolaj Peddie-Richers