All,

I decided to tackle my failing alternator and leaking water pump on my 04 545 over the weekend. The alternator is back on but i had to remove the crank case pulley/harmonic balancer to undo the dreaded last bolt on the pump. So now to replace everything I need to put a breaker bar on the crank case and turn it so I can get the ac belt back on (unless there is a easier way to do it). But I cant figure out what size the bolt is. I called the dealer and got no help. I have to order the socket but would like to know the exact size instead of using trail and error.

If anyone knows the size or can point me in the right direction to get it would be GREATLY appreciated.

Thanks,

 

I think its a 24mm

 

I'm pretty sure it's a 27mm socket

 

It's 27mm.
I changed the coolant pump on my 550i a week ago.

 

You can install the ac belt tensioner.

 

27 it is. I tried my 24 I use for the oil change and know its bigger than that. I'll stop by advance or somewhere today to pick it up.

Thanks Everyone!!

 

Although I hope I wont have to go back in again, it is good to know there is a belt tensioner option. Is that an easy install? Where did you get the tensioner from?

 

whoops, I couldn't remember if it was 24 or 27...

Was it easy getting the AC belt back on this way? I'm changing my water pump this weekend and hopefully I can somehow remove that bottom bolt without removing the crank pulley. At least someone on a forum said they were able to by using a flex head wrench.

 

No problem. And sadly I saw the ratchet wrench idea AFTER I pulled the crank off smh. I haven't put the car back together yet, knew my car had a leak and thought it was a hose didn't know it was the pump until after I pulled the alternator and traced the leak. Won't get it in the mail until tomorrow (2/26/14). Ill probably replace tomorrow or Thurs. Will report back once it's complete. It wasn't a compete waste however as my AC belt looks like it needs to be replaced anyway

 

Its the same tensioner as the serpentine belt tensioner,,its an easy install. Its an update but I don't know the number. Dealer or any online bimmer parts place should carry it. Check out this thread if u wanna take a look at it.
Anyone here changed an AC compressor on a 545i? - Bimmerfest - BMW Forums