hello,
took a glance at my m54 today and noticed the pulley directly under the alternator has a slight wobble to it. So, id like to replace it..

now i feel really stupid but i cant figure it out. i've gone through pics of m54 engines and looked at thread from the search feature to stumble upon belt change guides where they ID the pulleys. however they don't seem to match up to what my m54 looks like so i'm lost..
my car is a 2005 525i. according to the vin lookup, its an m54.

i can get pics tomorrow when its light out but for now, nothing.
perhaps its some sort of tensioner? however i had identified the tensioner as a different pulley which is located more towards the center of the car

help?

 

If you have a wobbling pulley....it most likely is your water pump going bad. Don't put this off.

 

Drop the drive belt and spin each pulley by hand - Idler Pullies, Tensioner Pulley, Water Pump pulley, PS pump pulley, Alternator Pulley - and see if there is any 'play' or noise in any of those pullies.

 

even with the belt on it, it has a slight bit of movement. its on its way out..
it is not the waterpump. the waterpump is the one in the center with the four bolts holding on the pulley to the pump.
it is a small pulley directly under the alternator. i will get pics tomorrow.. meant to do it today but got stuck xmas shopping.

 

I think that would be tensioner pulley.

 

that was my original thought, some kind of tensioner considering the way the belt was routed

can these be upgraded to a steel or aluminum? id imagine these are better? ive seen some other pully's on the ecs website you can upgrade to.

either way, tomorrow first thing ill take some pics and upload them. with access to a lift a few min down the road, this as diy should be rather simple.

 

The only upgraded pulley I've ever seen is the water pump pulley, which I HIGHLY recommend if you are replacing your water pump and/or pulleys. It's $35. As for tensioner and idler pulleys, go with INA pulleys.

you do not need a lift to replace those pulleys. I recently did both belts, all pulleys, water pump, and thermostat. Once you remove the fan assembly (easy, comes out in 2 minutes) everything is easily accessible from above.
good luck with the car.

 

here is a pic ive labeled everything.. the ones in question are the ones i labeled "Tensioner?"
both of these are now seeming to have a slight wobble..

can someone just confirm this on the the right side below the alternator is in fact a tensioner. if so how do i figure out if its hydraulic or mechanical?

im going to have to look into radiator fan removal diy. you say its easy but the last one i read into made it seem like a pita. with the car on a lift, it seems like it could be done in less than an hour without removal of the fan..

thanks for the help!

 

The pulley that's below alternator is called idler pulley. The other one that you labeled as tensioner is indeed belt tensioner. Both of those pullies wear due to age. Buy tensioner as well as idler pulley and replace them. While you are at it, check the condition of the drive belt and replace it if it's showing any deterioration.

 

thanks for the info! i appreciate the help! i will certainly get these replaced along with checking on the condition of the belts.
im assuming the belt tensioner is mechanical and not hydraulic?
i've also read you can upgrade to the hydraulic, but imo if mechanical has worked thus long, why change it.