Alternator Drive belt

[IrvineTim]

Build date 9/2015, three track days, 6000 miles, no failures, no issues. I turn the AC off. Just chiming in.

[Powerslide]

Originally Posted by CanAutM3

Was you A/C on or off when it hapenned?

And also - when was your build date? This happened to me as well - AC was on - July 2014 build. Replaced under warranty - went to track again with AC off and no problems since...

[Allank]

all of a sudden engine went into limp mode, and said battery not charging.

[bimmerboyE92]

For those that had the failure... was a new belt all that was needed? Or was the tensioner or something else found to be the root cause?

Looks like a replacement belt part # 11287848605 is less than $50. Cheap enough to bring a spare for track weekends.

[Mandi90TT]

Just bought one, for that just in case scenario.

Side note: who doesn't turn their climate control completely off at the track, and why not?

[Allank]

Climate control was totally off when mine went.

[FlyingLow78]

Originally Posted by Klenka

Just happened to me at autobahn country club end of the first 20 minute session 😥

What's your build date?

I've got 30K miles on my F80 and five track days, and so far no failures. My build date is November 2014. Last time out at Imola in July it was blazing hot and I left my A/C on the slowest fan setting so my GF and I didn't get soaked in sweat. I'm not out to set any lap records, so I'd rather be a lot more comfortable than gain .5 seconds.

[Mandi90TT]

To me, it's not about the time, it's about strain on the engine. Although the S55 cooling system is massively overengineered and there have been very few issues with cooling at the track reported, no reason to put additional strain on the cooling system with the A/C.

Anyways my F82 was picked up in Oct 14, so I suspect an early build date....but no issues at the track so far. Going to carry that extra alternator belt around in my track tool set from now on, though, after reading this thread.

[Allank]

Mine is a 2015. Not sure how to find when it was built. Third track day.

[Allank]

Did anyone else have a drivetrain malfunction warning come on when the belt broke, and go into limp mode?

[SakhirM4]

Originally Posted by Allank

Mine is a 2015. Not sure how to find when it was built. Third track day.

Its on the driver's side door jam.

[MaynardZed]

Originally Posted by Dave 90TT

Side note: who doesn't turn their climate control completely off at the track, and why not?

I keep the AC on sometimes when its really hot. I sweat my ass off enough in a fire suit when I'm in the race car, so I guess I just want to be comfortable when I get the rare chance to take the M4 on track.

[Erotic_taco]

Reviving an old thread.
Happened to me this past weekend. 2015 M4, Dec '14 build.
Battery charging error, alternator belt clearly in pieces. AC was off.
Did find a couple ball bearings like stated above plastered to the barrels of my front wheels.

[MaX PL]

If I get this belt is it an easy swap if it were to go at the track?

[Erotic_taco]

Originally Posted by MaX PL

If I get this belt is it an easy swap if it were to go at the track?

Belt would not be an issue to change, have to remove the air box and carbon brace to get at it. The issue is if your belt tensioner pulley bearing fails I'm sure that is more involved. You can put a new belt on but without that belt tensioner working properly it will shread another belt.

[Psychotic Mouse]

I had had this recently happen to me as well. So it seems like a general problem.

Mine is a 2015 M3 with 56’000 km on the clock. Apparently I seized three pulleys and had both belt shred themselves.

[Torfhinn]

I am also going to chime in as my 2015 M3 with a build date of July 2015 and 24k on the clock just ate my belt at the track and I had a 185 mile tow (free from roadside assistance, thank Crom) back to the shop.

This was my 3rd track day in this car and I have been out with and without AC on the track. However, when the pulley gave way and the belt went to hell I was windows down.

One thing that I am a little leery about is when my belt let loose I too got the battery charging malfunction warning and then within about .1 miles it went directly into limp mode, but I actually got an engine hot warning after limping the last .5 miles from the track and had lost a little antifreeze.

[Psychotic Mouse]

Originally Posted by Torfhinn

I am also going to chime in as my 2015 M3 with a build date of July 2015 and 24k on the clock just ate my belt at the track and I had a 185 mile tow (free from roadside assistance, thank Crom) back to the shop.

This was my 3rd track day in this car and I have been out with and without AC on the track. However, when the pulley gave way and the belt went to hell I was windows down.

One thing that I am a little leery about is when my belt let loose I too got the battery charging malfunction warning and then within about .1 miles it went directly into limp mode, but I actually got an engine hot warning after limping the last .5 miles from the track and had lost a little antifreeze.

My symptoms were Identical however without the Limp Mode. I was on a cool down lap though at the time I got the Battery charging Error. Then not long after that got the cooling error with a loss of coolant in the engine bay. I'll upload photos once I get a chance.

The only difference I had this time round was all other track days I have been driving with MDM and in automatic. This session I went out in full manual with all traction control off... While driving like this I missed a upshift once or twice and hit the rev limiter, not sure if this would add undue strain on the pulleys? (I doubt it thought)

[Torfhinn]

Originally Posted by Psychotic Mouse

My symptoms were Identical however without the Limp Mode. I was on a cool down lap though at the time I got the Battery charging Error. Then not long after that got the cooling error with a loss of coolant in the engine bay. I'll upload photos once I get a chance.

The only difference I had this time round was all other track days I have been driving with MDM and in automatic. This session I went out in full manual with all traction control off... While driving like this I missed a upshift once or twice and hit the rev limiter, not sure if this would add undue strain on the pulleys? (I doubt it thought)

On the long straight on the BIR Donnybrooke track I hit the rev limiter in 3rd gear and again I hit the rev limiter coming around turn 3 in 3rd gear, but I dont think that ripped the idler pulleys off.

Also I got the car back from the dealer and I talked with the shop foreman about the idler pulleys for both accessory belts. He was saying that these have a TSB for excessive bearing wear at "high RPMs" which is anything over 3500. BMW has updated this part several times and there is a new sealed bearing version available to the dealers with a higher strength stud bolt too.

Either way these cars are meant to blast down the track and hitting the rev limiter is not the likely cause.

[Psychotic Mouse]

Originally Posted by Torfhinn

On the long straight on the BIR Donnybrooke track I hit the rev limiter in 3rd gear and again I hit the rev limiter coming around turn 3 in 3rd gear, but I dont think that ripped the idler pulleys off.

Also I got the car back from the dealer and I talked with the shop foreman about the idler pulleys for both accessory belts. He was saying that these have a TSB for excessive bearing wear at "high RPMs" which is anything over 3500. BMW has updated this part several times and there is a new sealed bearing version available to the dealers with a higher strength stud bolt too.

Either way these cars are meant to blast down the track and hitting the rev limiter is not the likely cause.

Awesome insight. I was thinking that there must be a revised part seeming as most of the people here are Early 2015 Models.

[jeromeM3F80]

Originally Posted by Psychotic Mouse

Awesome insight. I was thinking that there must be a revised part seeming as most of the people here are Early 2015 Models.

same problem
M3 10/2014

[trungnguyen28]

Adding to this old thread. 2015 M3, was driving casually under 40mph in efficient mode. I hear a loud clunk, battery malfunction notice and then a car over heating notice. It's late right now and I got the car towed but found the belt had snapped. Not sure about the pulleys.

Not sure if it matters, but I did get the crankhub fix done recently as well.