Serpentine Belt Replacement

I'm replacing the serpentine belt, on my 2000 528it.
I've been reading some conflicting information on the size of the hex nut I need to loosen the tensioner. Can anyone confirm for me what the size of the hex nut is?

Some sites have said T-74, some have said T-60, does anyone know which it is?
Thanks guys.

Originally Posted by eknine9

I'm replacing the serpentine belt, on my 2000 528it.
I've been reading some conflicting information on the size of the hex nut I need to loosen the tensioner. Can anyone confirm for me what the size of the hex nut is?

Some sites have said T-74, some have said T-60, does anyone know which it is?
Thanks guys.

DON'T loosen the torx nut on the pulley, use a 16mm socket on the dead nut pictured. Attempt to turn clockwise and spring will compress as tensioner rotates. As you rotate clockwise, you will see two holes line up you can put a small hex key in or something similar, to hold the spring in the compressed position.

Originally Posted by eknine9

I've been reading some conflicting information on the size of the hex nut I need to loosen the tensioner.

I too was, at first, greatly confused by all the permutations for the mechanical and hydraulic tensioner nut sizes.

It turns out, more than you could possibly ask here has already been answered in these threads that you MUST read before you go any further!
- How to tell if you have mechanical or hydraulic belt tensioners (1) how to switch from mechanical to hydraulic (1) and what is the difference between the two types (1) (2)

If, after reading those few threads, you STILL have questions, then ask away ... (I doubt you'll have many questions left as quite a few people, including me, contributed to the tribal knowledge in those threads) ...

You MUST read those threads first before asking any more questions ...

Good luck.
The team is here for you, in its entirety, but you have to show you're worth helping!

alright well thanks for the info and the links guys.
I did a search and read a few threads and decided to replace my engine fan, and fan clutch since i was going to be that far in anyways.
I used the DIY on www.beisansystems.com and it was pretty much awesome. For reference the correct size torque head was a T-50, but like wagonthedog said it wasn't needed and a socket head on the dead nut worked just fine. However, unless you have an extended head, loosening the tensioner for the main drive belt is rather difficult due to how close the wrench head is to the drive belt, so it was more convenient for me to use the torque head to remove the second belt.

During the process I noticed two of my pulleys were squeaking a bit when i rotated them so in a couple weeks I'm going to make a project out of replacing a couple of the pulleys as well. Thanks guys, I appreciate all of the help, this car isn't as difficult to work on as I thought.

eknine9,

You should think about cooling overhaul, not just the pulleys.

Originally Posted by eknine9

alright well thanks for the info and the links guys.
I did a search and read a few threads and decided to replace my engine fan, and fan clutch since i was going to be that far in anyways.
I used the DIY on www.beisansystems.com and it was pretty much awesome. For reference the correct size torque head was a T-50, but like wagonthedog said it wasn't needed and a socket head on the dead nut worked just fine. However, unless you have an extended head, loosening the tensioner for the main drive belt is rather difficult due to how close the wrench head is to the drive belt, so it was more convenient for me to use the torque head to remove the second belt.

During the process I noticed two of my pulleys were squeaking a bit when i rotated them so in a couple weeks I'm going to make a project out of replacing a couple of the pulleys as well. Thanks guys, I appreciate all of the help, this car isn't as difficult to work on as I thought.

Ha, love the Shadowline!!!

Yes, they are indeed easy to work on once you get your legs and figure out how and where everything goes together. With that being said, cn90 is definitely correct... If you have pulleys getting noisy, you should have done it all. When cn90 gave me the same advice you just got, I more or less ignored him, put everything back together, then had to take it all apart again a week or so later because that which I neglected the first time, failed shortly after... At the risk of stating the obvious, your cooling system is only as strong as it's weakest link.

Thanks for the advice again guys.
I've been doing the cooling system in bits when I can afford to.

So far in the past 15k miles I've done.
-New Radiator
-New Radiator lines and fluid flush and refill
-New Overflow tank
-New Water Pump
-New Fan Clutch and Fan
-New Serpentine Belts

Got the Radiator, Lines, Overflow tank, and WP done at an indy... but I'm regretting that now seeing as they were all rather simple to get to.
I'd Love to have finished the cooling overhaul all in one go as I had read quite a bit of scary stuff about cooling system failure in this car, but the airbags in the rear suspension failed about 6 months after I purchased the car, so I just decided to break the cooling system into bits because I was worried about never having enough to do it all at once.

Originally Posted by eknine9

Thanks for the advice again guys.
I've been doing the cooling system in bits when I can afford to.

So far in the past 15k miles I've done.
-New Radiator
-New Radiator lines and fluid flush and refill
-New Overflow tank
-New Water Pump
-New Fan Clutch and Fan
-New Serpentine Belts

Got the Radiator, Lines, Overflow tank, and WP done at an indy... but I'm regretting that now seeing as they were all rather simple to get to.
I'd Love to have finished the cooling overhaul all in one go as I had read quite a bit of scary stuff about cooling system failure in this car, but the airbags in the rear suspension failed about 6 months after I purchased the car, so I just decided to break the cooling system into bits because I was worried about never having enough to do it all at once.

Yeah, I know what you mean... Once you get going on stuff, sometimes it's hard to find a stopping point. One thing I can tell you, provided you have the tools and a basic instinct for putting back together that which you took apart, this forum can enable you to do most any DIY. That is, if you have the time, and ideally, something else to drive while you're in drydock