FairfaxC32

Alternator is dead, no doubt. Dealership quoted me $1500 parts & labor. I almost died. I fortunately found the $1100 alternator (valeo brand) for around $270 at www.autohausaz.com, and it's on the way. I'm guessing my car has an automatic belt tensioner, but I've never replaced an alternator before. I already removed the left air intake hose, and air pump, so I can get to the dead alternator. Searching this forum didn't yield and DIY installs for a C32 alternator. Any advice and pics would be greatly appreciated. Thanks!

mleskovar

Haven't done it but I can remember reading that changes have been made to the serpentine belt idler pully so be sure to check if yours needs it. Let us know how it goes.

pshek

I think the C32 AMG uses a bosch alternator. Valeo alternators have a different pulley. You would probably need to remove the old 8 rib pulley and put it on the new alternator. Use a pulley puller.

MBTech21

There is no pulley puller- these alternators don't usually come with pulleys. You remove the nut off the stator and the pulley falls off- the new alternator will come with a nut on it..no pulley. Other than that - biggest tip is to make sure the battery is disconnected and to push the bolt hole bushings back (outward), so you don't fight the new alternator into the bracket.

FairfaxC32

Do I need to loosen the serpentine belt tension before removing the nut from the stator, and if so, how do I do this?

MBTech21

Usually we would do it with an impact gun, with the alternator off- so you have to release the belt first-obviously.
I can't see any one charging more than 1-1 1/2 hrs for this job, so it might be better seeing if another shop gives you a better deal on installing your part.

FairfaxC32

Pics attached - what is the proper way to loosen the belt?

FairfaxC32

I think the pic below is the tensioner pulley. The part circled in green shows the bolt. A wrench goes over and around the larger "nut" part, but I have no clue what to use on the part that looks like a hex star bit. Any ideas?

mleskovar

Isn't it a reverse torx?

FairfaxC32

yeah, I figured out how putting torque on the bolt loosens the belt pressure - got that off the alternator, but I'm having a tough time removing the alternator. I got the wires disconnected, and the top and bottom bolt removed, but there's an inner sleeve that the top bolt went through that is still holding the alternator in place. I'm kinda stumped.

FairfaxC32

Does the bolt the green arrow is pointing to pull straight out or is it threaded? It doesn't seem to be shaped for a socket to fit on it.

mleskovar

MBTech21 wrote "...biggest tip is to make sure the battery is disconnected and to push the bolt hole bushings back (outward), so you don't fight the new alternator into the bracket"

FairfaxC32

Yeah, and pshek said to use a pulley puller.

Besides, I was having difficulty removing the OLD one, not installing the new one.

mleskovar

If it helps putting it in you'd think pushing the bushing would help getting it out is what I meant.

FairfaxC32

Ok, finally got the alternator replaced and everything except the ESP is working fine (probably needs a reset somehow). For other newbies to alternator replacements, here are some basic guidelines with pics.

1. Remove engine cover, left air intake (black plastic stuff), air filter over battery, and the air pump (including mounting bracket).

2. Remove battery cables from battery.

3. Jack front of car up and put onto jack stands. Some access to the alternator will be needed from underneath the car.

4. Loosen serpentine belt. See tensioner pulley in Picture 1 below. Use a 15mm socket, and torque the pulley counterclockwise; as you do, the whole pulley will move to the left, reducing the tension on the belt. Do this far enough and you'll be able to slip the belt off the alternator. There is a bolt head to the right of the alternator that I secured the serpentine onto, so that the belt wouldn't come off all the other pullies.

5. Remove both wires connected to the back of the alternator.

6. Remove both bolts that secure the alternator to the engine. See Pic 2 below.

7. Use a pry bar to loosen/remove the alternator.

8. Remove the old alternator - this can take some patience, as the space is very cramped.

9. See Pic 3. Inside the bracket there is a bushing which you should tap out (away from the alternator) a little so when you put the new alternator in there's a little room. Do this on the bottom bracket as well.

10. Install new alternator, connect both wires, secure with original bolts.

11. Reinstall battery cables

12. Reinstall stuff in step 1.

mleskovar

Congratulations and thanks for the write up. I believe ESP is reset by turning the wheels lock to lock. There's a sticky on the W203 forum for faults that occur after battery is disconnected and reconnected.

vettdvr

Good write up and photos. Thank you I have added to my MB file. Jim

MBTech21

Sorry, was off the board for a few days, but I see you got it done.
Good writeup- the only thing I would change is when loosening the belt tensioner, you should use a inverted torx on the tensioner- the 15 mm actually holds the pulley on and it is possible that you could loosen the nut rather than slacken the tensioner.

mleskovar

How is the belt tightened? After 100K miles my serpentine belt still looks great, no cracks or fraying anywhere, but I'm starting to get anxious. How long do they usually last?

FairfaxC32

The tensioner pulley automatically puts the correct tension on the serpentine belt (it feels like it's spring loaded). I don't know what the service schedule is for your car and the serpentine belt, but I would suspect this to be changed out before 100K as part of a preventitive maintenance schedule.

whestworld

Hi Fairfax

This is probably 4 of the very best posts on the whole of the internet!

I'm about to do mine and would like to know if I need to remove the pipe-work above to gain access and if I do is there any fluids that will drain out?

Also.... where can I purchase a re-con unit from or do you guys recommend new?

regards

james

lkchris

How do you know if you haven't compared it to official Mercedes procedures?

http://www.startekinfo.com/StarTek/o...tedDocId=11498

whestworld

You're not supposed to take a comment like that literally

Anyways, thanks for the link BUT I'm based in London and need this thing sorted ASAP . I'm quite into DIY which is why I like the info posted by fellow Merc-idians.

Roger Hansson

what tools did u use for alternator bults ?

eugenke

Hello.

So i bought new alternator (Magneti Marelli) as per VIN code and was slapped with an compatibility issue, unfortunately.
The pulley cannot be replaced, because it does not fit.