Idler Pulley Replacement? Aux Belt broken

[MetalsMan]

Gentlemen,
Last night I got a charging malfunction warning, and the ac stopped blowing cold. I checked the engine bay and can see that the auxillary belt has either fallen off or has shredded. I have seen some reports that the idler tension pulley has gone bad on these cars and has needed to be replaced. I track the car, so maybe it's simply wear and tear.

In any case, I am trying to decide to replace it and the belt myself or have the dealer do it. Anyone do this at home? Have any input?

Thanks
Jason

[jmciver]

This job is a bit more of a PITA on the S55 compared to other cars I have done this job on, but it is very DIY’able. I recently did both belts and changed out the idler pulleys and belt tensioner as well. There are a few good videos on YouTube that show how to do it….

[jfritz27]

Originally Posted by MetalsMan

Gentlemen,
Last night I got a charging malfunction warning, and the ac stopped blowing cold. I checked the engine bay and can see that the auxillary belt has either fallen off or has shredded. I have seen some reports that the idler tension pulley has gone bad on these cars and has needed to be replaced. I track the car, so maybe it's simply wear and tear.

In any case, I am trying to decide to replace it and the belt myself or have the dealer do it. Anyone do this at home? Have any input?

Thanks
Jason

Out of curiosity, how many miles on the car?

Good luck with the repair

[MetalsMan]

Just rolling over 40k

[richf80]

I replaced mine at 80k. It is a PITA to change these belts but doable. You have little space to work with because of the fan. You can drop the fan, but there are more things to remove to get the fan down. Good luck.

Edit: I referenced this thread to get the fan down for more space: VTT Crank Bolt Capture install guide https://f80.bimmerpost.com/forums/sh....php?t=1594892

[jfritz27]

Originally Posted by jmciver

This job is a bit more of a PITA on the S55 compared to other cars I have done this job on, but it is very DIY’able. I recently did both belts and changed out the idler pulleys and belt tensioner as well. There are a few good videos on YouTube that show how to do it….

His videos were definitely helpful -- in those, he doesn't change the idler pulleys. It looks however that once you establish access to do the belts and tensioner change in the way he did, you shouldn't need to do anything additional to change the idler pulleys, they seem like they're right there. Is that about right?

Anyone have the correct torque specs for the various bolts in his videos?

ECS has a kit to replace all this stuff:
https://www.ecstuning.com/b-genuine-...1288088632kt1/

[MetalsMan]

I'm going to start removing things and see how tight it is. Would think if I can get my hand on it, should be able to get tools to it. Will follow up. I appreciate the feedback and votes of confidence!

I have an appointment with the dealer, but not until Wed, and I want to start prepping for a track event so I am fearful they'll have it for days on end

[jmciver]

Originally Posted by jfritz27

His videos were definitely helpful -- in those, he doesn't change the idler pulleys. It looks however that once you establish access to do the belts and tensioner change in the way he did, you shouldn't need to do anything additional to change the idler pulleys, they seem like they're right there. Is that about right?

Anyone have the correct torque specs for the various bolts in his videos?

ECS has a kit to replace all this stuff:
https://www.ecstuning.com/b-genuine-...1288088632kt1/

Yeah, they are right there. Once you get the belts off, and then the tensioner off, the idler pulleys are easy to get access to. As was mentioned above, you don’t have much room with the fan installed, but removing the fan seemed more of a PITA than just belts & pulleys.

FWIW, I did my belts, tensioner and idler pulleys at 50k miles using an old school preventative maintenance mentality. Everything actually looked pretty good, too, so I feel confident I am good for at least another 50k miles .

[MetalsMan]

Damn, it's tight in there. Hard to tell from this pic, but looks like one of the tensioners has gone bad, it appears crooked and out of line with other auxiliary pulleys. Idler pulley appears to be fine. Sucks that the water pump belt has to be removed to replace aux belt.[IMG]undefined[/IMG][IMG]undefined[/IMG]

[jfritz27]

Originally Posted by jmciver

Yeah, they are right there. Once you get the belts off, and then the tensioner off, the idler pulleys are easy to get access to. As was mentioned above, you don’t have much room with the fan installed, but removing the fan seemed more of a PITA than just belts & pulleys.

FWIW, I did my belts, tensioner and idler pulleys at 50k miles using an old school preventative maintenance mentality. Everything actually looked pretty good, too, so I feel confident I am good for at least another 50k miles .

Thanks -- any chance you have any torque specs? Kies has a video for the N55 with values for the tensioner and idler (deflection) pully, not sure if they're same or not. (I think at least tensioners on both use an E12 head). Also would be nice to know for the four 10mm's that you need to remove on the water pump pulley. Really sucks that free newtis is dead.

I ordered the Conti belt wear tester and am going to try and see if that tells me anything about status of my belts at around 40K with moderate track use over past few years

[MetalsMan]

Pic did not attach

[jfritz27]

For reference, here is a pic I found on eBay which gives you a good look at the various components in relation to one another, and the belt path

[MetalsMan]

Very Helpful

[hC1001]

Originally Posted by jfritz27

Thanks -- any chance you have any torque specs? Kies has a video for the N55 with values for the tensioner and idler (deflection) pully, not sure if they're same or not. (I think at least tensioners on both use an E12 head). Also would be nice to know for the four 10mm's that you need to remove on the water pump pulley. Really sucks that free newtis is dead.

I ordered the Conti belt wear tester and am going to try and see if that tells me anything about status of my belts at around 40K with moderate track use over past few years

Torque specs attached.

[jfritz27]

Originally Posted by hC1001

Torque specs attached.

Awesome, thank you!

[MetalsMan]

anyone remove the upper deflection pulley? The oil cooler lines are in the way, can't get a socket in there easily.

[jmciver]

Originally Posted by MetalsMan

anyone remove the upper deflection pulley? The oil cooler lines are in the way, can't get a socket in there easily.

I disconnected the oil cooler lines from the oil filter housing to get better access in there. Just make sure you don’t lose the two o-rings that go on the piping in the oil filter housing piping connection, and use plenty of rags/absorbent materials in there of course…

[MetalsMan]

Got this thing out over the weekend. Bearing seems to have seized and melted the internals. Getting it out was a bitch. You need a t50 stubby torx socket to get a ratchet on it. I decided to replace the tensioner (idle pulley)as well while I was in there. Wish I would have just leave it be. Getting it out wasn't to hard, but getting the bolt lined up and back in with the new one took a lot of patience. The deflection pulleys are not the same FYI. In many pics they look identical, but the lower one is a little larger in diameter.

[jfritz27]

Originally Posted by MetalsMan

Got this thing out over the weekend. Bearing seems to have seized and melted the internals. Getting it out was a bitch. You need a t50 stubby torx socket to get a ratchet on it. I decided to replace the tensioner (idle pulley)as well while I was in there. Wish I would have just leave it be. Getting it out wasn't to hard, but getting the bolt lined up and back in with the new one took a lot of patience. The deflection pulleys are not the same FYI. In many pics they look identical, but the lower one is a little larger in diameter.

Well, that needed to be done! Nice. You kept the fan in place I assume? Also, did you remove oil lines like jmciver did?

[MetalsMan]

Late reply here. Yes, kept the fan in. It's a conundrum for sure. It would be much easier without the fan in there, but removing it is just as much work. I also left the oil lines in place, but if I were to do it again, I believe I would disconnect and try to tie those out of the way. Good news is, it's done and I took it to Autobahn Country Club this past weekend and everything held up. Pretty satisfying to repair myself, though it wasn't fun

[jfritz27]

Originally Posted by MetalsMan

Late reply here. Yes, kept the fan in. It's a conundrum for sure. It would be much easier without the fan in there, but removing it is just as much work. I also left the oil lines in place, but if I were to do it again, I believe I would disconnect and try to tie those out of the way. Good news is, it's done and I took it to Autobahn Country Club this past weekend and everything held up. Pretty satisfying to repair myself, though it wasn't fun

Cool, thanks.

jmciver Would you mind sharing what needs to be done to disconnect the oil lines for this? Is it just removing the one bolt circled below, then just pulling down on the lines? Can't tell for sure if that bolt is what's securing them or not. Thanks!

[jmciver]

Originally Posted by jfritz27

Cool, thanks.

jmciver Would you mind sharing what needs to be done to disconnect the oil lines for this? Is it just removing the one bolt circled below, then just pulling down on the lines? Can't tell for sure if that bolt is what's securing them or not. Thanks!

Yes, that is the bolt that connects the tubes to the oil filter housing. But before you can pull out the tubes, you also need to unscrew a bracket that also holds the tubes in place further down (you can see that bracket in the eBay pic a few posts up). When you pull the tubes out, there should be a pair of o-rings on them. If you don’t see them, they are still in the oil filter housing. You can stick your finger (or a pic tool) to get them out if necessary.

Technically (according to BMW) you are supposed to replace those o-rings, but I did not and did not have any issues or leaks when I put everything back together (the o-rings looked fine and were not deformed).