Alternator bolt and tensioner don't play well together

[shiboujin]

http://www.realoem.com/bmw/showparts.do?model=HD53&mospid=47404&btnr=11_1399&hg=11&fg=18

My motor came without the alternator. So I got one. It didn't come with bolts. So I got some. Then I was told by a buddy a tensioner went on the top bolt. So I got it.

But it doesn't fit.

Basically I bolted the alternator bolt down but theres about an inch or two of blank space left where I could thread down if there were more threads. I put the tensioner on but it just wobbles around and can slide back and forth fairly easily. I looked at the realoem parts (#6 is the bolt and #5 is the tensioner). I didnt bother with the cap #7 but do I need that? What am I missing? I'm passing by the parts department today so I want to get as much as I can in one foul swoop.

[brandon11130]

While i was getting raped today at my local bmw dealership, i learned that there are 2 types of tensioners, one is hydraulic with a strut or somthing, and the other is different. Maby the different tensioner setups go with different alternators? they were both listed for 1992 NV m50's
on realOEM.com it shows the 2 different types.

[Drew325is]

Sounds kinda like the same problem I ran into...there's two different tensioner set ups:

[shiboujin]

Oooh. I think I have a hydraulic one lying around! I need to get pix up.

What did you guys do? mechanical or hydraulic?

[Drew325is]

I'm running hydraulic, but I didn't have a choice as the VAC Motorsports billet oil filter housing requires it that way. I'm not sure there'd be a lot of difference though...maybe just go with whatever set up is easiest and quickest for you to get working.

[shiboujin]

I'm def missing the rest of the assembly. If you look, theres another hydraulic tensioner on the bottom. I guess theres 2 but the other one I have doesn't fit

[Drew325is]

This is the best photo I have on hand of my set up...you can see where parts 2 and 4 from the lower realoem diagram above sit between the alternator and the pulley.

[shiboujin]

see i have that lower pulley but where does the top one go? grr...

[evil_twin]

Yoshi, does the pulley line up with the other pulleys when it's pulled out or pushed in?

[shiboujin]

Pushed out I would say. I think I def need the mechanical one since the non mechanical one doesnt seem like it would fit with the other hyrdaulic tensioner. *shrugs*

Where you been viet?!

[evil_twin]

Hey what oil filter housing do you have? I remember when we did my friends swap, there is a plastic housing and there is a metal housing, and for his because we used a bunch of things, we had to use the metal one.

But from the 2 pictures, there looks to be a spacer where that bolt is to push the pulley out.

I've been playing with the motor and working like a bitch. Right now I am in Ohio. Oh BTW, i got your text message, and I responded back but you signed off already.

[shiboujin]

Yea the power went out at my house >_< I went by and yanked the radiator i needed anyway. No one seemed to care lol. Whats the deal with the eta sitting there in the back? That guy want to get rid of it? :)

I def have a metal oil housing.

Doesn't make full sense. I have the hydraulic tensioner, that's what makes the belt look like a backwards "B". So... what the farg goes on the top tensioner on my alternator? I got both the right part #s...

[PiercedE30]

You have the wrong idler. It should have a metal piece on the back of it.

[shiboujin]

they are all the same part # tho. Or is it lacking a part? Got any part #s?

[PiercedE30]

It's lacking the part that the idler mounts to. It goes between the alternator and the pulley and is held in by the bolt.
Look at Drews picture. Look at the pulley and bolt. Now look at where it is mounted and notice the aluminum piece between the alternator and pulley. That is the part you need. I can't find it on RealOEM for some reason.