[Mark23rhodes23]

Just changed the poly v belt on my 2013 330d.
Really straightforward:
Remove engine cover,
2 x 10mm plus 1x 30 or 35 torx bolt.
This removes cover / sound deadening on the front of the engine.
Next, the twin roller tensioner has a 16mm socket on it.(circled in orange)
Tighten / rotate clockwise which releases the tension.
A hole in the tensioner lines up with a hole in the body (red dots to red dots)
I used a T25 torx Allen key as a locking tool to hold it in place. A thin screwdriver would work or Allen key.
Then remove the old belt (after taking a photo / drawing a diagram of the path of the belt)
Check all the rollers
Install new belt, making sure it aligns correctly on the rollers etc.
Very slightly tighten the 16mm bit to take the tension off the locking tool.
Remove locking tool and very slowly slacken / anticlockwise rotate it to allow the tensioner to tension the belt. Check it is correctly aligned on all the pulleys.
Reinstall front cover.
Job done. Easy peasy. lemon squeezy

[Allworth]

Just to add to this thread an image of a recent auxiliary (v) belt change.
Outer side of a belt has not got any cracks or visible wear, but inner side has those grooves to match its counterpart on pulleys and is really worn.
Belt is from N47 engine, 12 years old.

[TurboWeasel]

Thanks for that. Been meaning to check mine. How many doubloons do BMW want for a belt?

[Allworth]

Originally Posted by TurboWeasel

Thanks for that. Been meaning to check mine. How many doubloons do BMW want for a belt?

Very affordable, almost free when one is really needed.
What's expensive is guessing on what is making a noise; idle pulley, crank pulley, alternator clutch, AC.

[Techno 9000]

Hi Allworth,

You mention the car is twelve years old, but how many miles has the car done?

[TurboWeasel]

Originally Posted by Allworth

Very affordable, almost free when one is really needed.
What's expensive is guessing on what is making a noise; idle pulley, crank pulley, alternator clutch, AC.

Had a search around last night and all of the stuff on the front is actually pretty reasonable, except the crank pulley and AC pump.

I do have a slight whirring/whine noise which recently developed, and seems to be gradually getting louder. It only happens at idle when the engine is hot. AC on or off makes no difference, so hopefully something cheap like an idler pulley or water pump.

[Leeg1633]

Not a job I would of thought to attempt myself, but as its so simple I'll check mine tomorrow

[Allworth]

Originally Posted by Techno 9000

Hi Allworth,

You mention the car is twelve years old, but how many miles has the car done?

120k miles, and this is mostly motorway, no south big city crawling.

[Sasquartch]

Just to add, if anyone removes their belt to inspect it and decides it's OK, make sure it is put on the same way round as it came off as they wear in a particluar way