535i V-belt change (alternator)

[Mass535Love]

I got the new belt and need to change it. I have a few questions.

1. Which bolt(s) is or are the "belt tensioner mounting bolts" ? I saw 2 that were 19mm and loosened them but couldn't remove the belts. These bolts had markings above and below that looked like v^v^v^v. Not on the bolts themselves but on the mounting bracket. I loosened them and nothing moves still

2. What or where is the tensioner? I thought I loosen the one bolt (one talked about above) and the unit swivels to release pressure on the belt. Remove/replace belt and tighten. Is this wrong? Although nothing swivels at this point.

3. Is there anyplace that you guys know of that does a step by step with pics? Sorry to be such a newb but once I do it the first time I know but I have yet to do it and have barely a clue. I changed a belt once on another car and that was simple. Just turn the bolt which pulls back the pulley (spring loaded I believe) and that relieves pressure. I'm dumbfounded on my bmw.


Thank you guys so much in advance for any and all help on the matter.

[bahnstormer]

bentley manual =]

[Mass535Love]

I have one and it's pretty vague. I couldn't locate any pics of what these correct bolts are. There's only text. Loosen bolt, remove belt, replace belt, tighten bolt. Although it does mention a crowfoot wrench I believe.

Thanks though but I've been there :) Unless you know exactly what page it's on with pics :)

[Kalevera]

The tensioners on the M30 are a bit awkward, because they usually break.

On each of the three tensioners: there are two nuts, one towards the rear of the car, which will loosen the assembly a bit (only undo it one or two turns). The other side should have a toothed nut mounted on the bolt that interacts with another set of teeth on the respective accessory's mounting bracket. The problem is that, as was once told to me, "there's not an M30 on the planet that doesn't have stripped teeth". In that case, you'll need to get a large screwdriver (or a piece of metal...anything long and thin with some strength to it) so you can manipulate/pry the mounting brackets. Otherwise, get a socket or box wrench on there and turn away -- loosen it to remove the old belt (if the old belt is still on there) and to install the new one, then tighten it to set things. Again - the nut on the other side has to be tight enough so that the toothed geer will stay in place on the bracket (and hence, move), but not SO tight that it's a strain to move the assembly (you'll probably break some teeth in that case). Loose is "towards" the engine block, tight is "away".

Also, when you tension the belts: tighten them so that you get ~ 1/2" of travel when you press down on the point equidistant between the two cogs. That's generally tight enough to prevent slipping, but not so tight as to mess up bearings. Finally, you'll probably have to tighten them up again after a few miles (because they'll sometimes stretch a bit).

Best, whit

[callen]

My 535 had stripped teeth from previously un-educated newbe changed the belts. Purchased new brackets (relatively inexpensive) from dealer and worked like a champ. If you loosen all the bolts that hold the accesory (alt,A/C etc) then slowly turn nut with teeth it will move on in so you can remove belt. This system works beutifuly. Once you get to stripped teeth and screwdriver stage its a real pain in the a$$. Lowell if you still have questions send me a pm and I'll explain further and answer any questions.

Callen

[callen]

OOPs for Mass535 love not Lowell.

[Mass535Love]

:) it's all good. Let me get back under there and figure it out. Or atleast try to. I'll let you know how it goes. Thank you for your help.

[Mass535Love]

Well at this point I have gotten it loosened, thank God. I wasn't able to get the first belt loose enough to get it off. Should I have to pry and tug by hand or should it get so loose that it flops off easily with just a finger or two? I'll keep trying. That darn thing is tough to move so it's loose enough to get off but I'll keep at it.

[Kalevera]

You could just cut the old belt. You're not planning on reusing it, are you? :)

Generally, you can pry them on, but life's a lot easier if the tensioners are just loosened enough.

best, whit

[callen]

If memory serves some of the belts do need a little forcing to get on and off......were you able to roll the toothed bolt all the way in on toothed bracket?

[Mass535Love]

I figured out how to do it, thanks to the help you guys provided and my Bently manual. I just ended up cutting off the one belt (PS I believe) as I could not loosen it enough to get off.

When I did it I was able to pull the toothed bolt all the way out. I kind of messed up and loosened the toothed side first. I don't know if I stripped it or broke any teeth but when putting it back in and tightening it (from the back this time, doing it properly) it held with no problem so all seemed fine. I would have never thought on my own that you loosen and tighten from the rear.