[Maxwagen]

My F31 has 62k on it, and I've got it marked down in my records (following Mike Miller old school BMW maintenance) that it's due for a belt. Nothing is making noise, but I've had belts go on cars in the past, and want to stay ahead of it. I've done my own belts in the past on other cars, and will probably tackle this one myself if it doesn't seem to difficult without special tools. Other than tensioner and idler, is there anything else I should change along with the belt on these cars?

[auburnf30x]

That should be it. I'm about to do the same myself, although most say the interval is 80k on these cars. I still prefer to do things sooner than later.

[lucasborka]

That's all you need. Tensioner is 38nm and idler pulley 60nm

[F32Fleet]

Nope

[Maxwagen]

Anyone have a good tutorial? I’ve done this myself on other cars, but I feel like there is always something I need to be aware of. I searched YouTube, but I can’t find anything for the B48.

[Aziego]

Have any of you changed the belt and tensioner on the B48 yet? Seems like one of the 3 bolts holding the tensioner in place is blocked by the intake. Wondering if I can use a box wrench to take the top bolt out. Seems like a lot of work to take the intake manifold out to remove one bolt.

[Alow]

Aziego Did you end up taking off the intake manifold to replace the tensioner? I have the same problem on my B46. I can't take the top bolt off even with a box wrench due to the intake manifold.

[F32Fleet]

Originally Posted by Maxwagen

My F31 has 62k on it, and I've got it marked down in my records (following Mike Miller old school BMW maintenance) that it's due for a belt. Nothing is making noise, but I've had belts go on cars in the past, and want to stay ahead of it. I've done my own belts in the past on other cars, and will probably tackle this one myself if it doesn't seem to difficult without special tools. Other than tensioner and idler, is there anything else I should change along with the belt on these cars?

Have a torque wrench?

[e2p71828]

I have a 2013 328i F30 with about 92k miles, still on original serpentine belt. I am looking to replace it and the tensioner. But the current belt still seems in pretty good condition, much better than some of the Youtube videos showing (how to replace the belt and) the old removed belt. Now I wonder maybe I can wait for another year or another 10k miles?

Please take a look at the two pictures I took of my current belt. What do you think?

Originally Posted by auburnf30x

That should be it. I'm about to do the same myself, although most say the interval is 80k on these cars. I still prefer to do things sooner than later.

[Billfitz]

I'd change it.

[e2p71828]

Thanks for your input!

This may not be the right thread, but let me ask here anyway - so the battery on this car is also still the original, after 10+ years. I have been thinking of replacing it since a few years ago; but this one just seems to be strong, with no sign of hesitation to start engine (with auto start/stop for all the 10+ years) and no errors on other electrical devices.

I bought an Ancel BD300 to read the battery charging status, and the reading is always between 70% and 80%. Elsewhere I read that BWM F30 design is not to charge beyond 80%, to prolong battery life.

So what to you think? Should I proactively replace the battery or wait till some signs of a weak battery?

Originally Posted by Billfitz

I'd change it.

[Billfitz]

If it ain't broken don't fix it. The problem with a belt is you can't see inside it to be sure if it's ready to let go or not, so once you get to a certain mileage prudence dictates you change it just in case.
You can tell if a battery is good or bad. If you're in doubt the way to know is to charge the battery to at least 12.5 v, disconnect the negative terminal. If it measures more than a 0.3 volt loss overnight the battery is suspect. You have to measure it with a meter at the battery, otherwise if there's a parasitic drain it will start sucking away voltage as soon as you reattach the negative terminal.

[e2p71828]

Wow, thanks, Billfitz, for the insight! And it makes sense. I will go ahead replacing the belt and the tensioner, and will test and watch the battery. 10.5 years so far of original battery should be close to record?

Originally Posted by Billfitz

If it ain't broken don't fix it. The problem with a belt is you can't see inside it to be sure if it's ready to let go or not, so once you get to a certain mileage prudence dictates you change it just in case.
You can tell if a battery is good or bad. If you're in doubt the way to know is to charge the battery to at least 12.5 v, disconnect the negative terminal. If it measures more than a 0.3 volt loss overnight the battery is suspect. You have to measure it with a meter at the battery, otherwise if there's a parasitic drain it will start sucking away voltage as soon as you reattach the negative terminal.

[Billfitz]

10.5 years is pretty good. Mine is past 8 years.

[nh90crxsi]

I would say it’s such a simple and not expensive thing to change, and if it breaks and leaves you needing a tow or worse

I just feel like for 1.5 hours of your time or less and a VNE belt tension and a BMW belt (71 bucks for the tensioner, 21 bucks for the belt)
It’s worth the attention

[e2p71828]

Yup, both you and Billfiz share the same opinion and I get it. Thank you.

I have watched several videos on Youtube on how to replace the belt and the tensioner. Have ordered parts too .

Originally Posted by nh90crxsi

I would say it’s such a simple and not expensive thing to change, and if it breaks and leaves you needing a tow or worse

I just feel like for 1.5 hours of your time or less and a VNE belt tension and a BMW belt (71 bucks for the tensioner, 21 bucks for the belt)
It’s worth the attention

[Orion4]

The technology in the newer belts doesn't show the stress as visually as the old belt of the 70-80. But when they do fail, it can be very expensive. Change belt, tensioner and Idler pulley as a set (My N55 setup). Cheap, easy insurance.

[e2p71828]

So I replaced the tensioner and the belt. No regret but just curious - the replaced belt indeed seems to be in good condition after 10.5 years and 92k miles, much better than those shown in the Youtube videos teaching how to replace it. I even now suspect that the belt was replaced once without me knowing ?

[Jvac]

Originally Posted by e2p71828

So I replaced the tensioner and the belt. No regret but just curious - the replaced belt indeed seems to be in good condition after 10.5 years and 92k miles, much better than those shown in the Youtube videos teaching how to replace it. I even now suspect that the belt was replaced once without me knowing ?

Possibly it was changed once, but what the others are trying to say is you can't tell by looking. I remember reading somewhere on here that there is a special tool used to measure the wear on these belts. Without the tool, you have no objective means of determining its condition.

[Hobie18]

I changed my original belt with 120K miles on it. Belt was in very good shape. Tensioner looked in good shape as well. New tensioner was quieter.

As for the battery. Replaced mine at 9.5 years. It had not failed yet, but was weak cranking. Stop start was rarely working since the battery was charging. High and low temperatures kill weak batteries.

[Billfitz]

Start/stop kills batteries too, because an engine that's not running can't charge the battery, while repeated start/stop cycles suck out charge like a vampire.

[e2p71828]

Thanks for the data point. So a BMW original belt can last long and still look in good shape. When it comes to the tensioner, my old and new ones sounded/sound the same - quiet. Still I now at least do not need to worry about the belt or the tensioner for another 80K miles .

Originally Posted by Hobie18

I changed my original belt with 120K miles on it. Belt was in very good shape. Tensioner looked in good shape as well. New tensioner was quieter.

As for the battery. Replaced mine at 9.5 years. It had not failed yet, but was weak cranking. Stop start was rarely working since the battery was charging. High and low temperatures kill weak batteries.