Broken fan belt after alternator install

Helo all << been a member since 2010 , but just recently been active on this site.. have learned a great deal on my 05/545 from everyones input and expertise and would like to thank all u guys up front...
i just recently instaledl a aternator.( valeo ) and a new belt.To make a long story short , my belt broke and took out my a/c belt and broke a radiator hose lost water and overhaeated on the fwy>> after i installed the alternator everything looked good took it for a 5 mile test run all was good. two days later comin home from a 30 mile run my belt broke.....when i installed the alternator i checked everything and pulleys looked good tensioner looked good.. i dont know why my belt broke<<<

has any one experienced this before ? and if so wat was the cause..

Based on the info you've provided, I'd say one of the pullies is not perfectly straight (damaged/not installed correctly) or one of the pullies is seizing (like compressor pulley).
Spin each pulley by hand and see if you can identify the culprit pulley.

pcy thx for the reply...i did.. and they both spin freely.. was thinkin to just replace all of them and hope for the best. theres not much to installing them.. they where fine before i changed the alt... is there a certain way to align them?

Did you use something like this:

http://bengkel234.us/en/137-bmwn62w1...installer.html

Ensure everything is torqued down to specs. The pulleys have to be aligned as well.
It's not so much the alignment as it is the torque (primarily). Torque should align everything, not always the case but usually. Also the belt has to be centered on EVERY pulley, especially the topside (non-grooved). Hopefully you didn't actually over, but got the warning and immediately pulled over.

I did pull over immediately,,,, hopefully nothin else pops up after I getter runnin,, thx for the input

Sure thing I'm gonna replace all the pulleys and radiator hoses and do a coolant flush as well

Originally Posted by boramkiv

Did you use something like this:

http://bengkel234.us/en/137-bmwn62w1...installer.html

Ensure everything is torqued down to specs. The pulleys have to be aligned as well.
It's not so much the alignment as it is the torque (primarily). Torque should align everything, not always the case but usually. Also the belt has to be centered on EVERY pulley, especially the topside (non-grooved). Hopefully you didn't actually over, but got the warning and immediately pulled over.

i didnt change the a/c belt so didnt need that tool , but looks like ill need it now.. since that belt broke too,,,

Originally Posted by H F

i didnt change the a/c belt so didnt need that tool , but looks like ill need it now.. since that belt broke too,,,

Yeah putting the AC belt on without the tool got the better of me. I bought a cheaper tool to install stretch belts but it wasn't the same design and there wasn't room for it to fit past the bracket that supports AC lines. I needed the car quickly so I threw in the towel and brought it to my mechanic. 5 minutes later (no charge) I was in business.

Agree with other posters that it is important to visually check to make sure the alternator pulley is perfectly aligned with the other pulleys (a long straight edge such as a level works well). If the alternator is not seated against the alternator bracket squarely (yes the dreaded alternator bracket with the profile gasket underneath that likes to leak and requires raising the engine off its mount to remove the last bolt) the pulley will also be out of alignment and stress the belt. Also the wrong pulley or a cocked pulley can cause the same thing. Examine both edges of the broken belt for wear to see if the belt was being pushed out of alignment.

Other possibility could be belt tension if you removed and reinstalled the tensioner. If you just took the tension off of it while uninstalling and installing the belt then it shouldn't have changed.

I carry my old belts in the trunk as backups for the road. I don't carry all of the tools necessary to install it myself but at least I can hand the backup belt to a mechanic to install instead of waiting to obtain a belt to get back on the road. If you didn't keep the old belt you may want to buy two so you have a spare. If the reason the belt broke is not that it was defective and you can't discover another reason, the next belt probably won't last much longer than the last one and you need to be ready to replace it on the road. I would also carry the proper torx bit, breaker bar and 3/16" drill bit for a couple of months in your trunk so you can install a replacement yourself on the road until you are sure you are "out of the woods" so to speak.

Since you said the problem started after the alternator was replaced and new belt was installed, are you absolutely sure the alternator pulley (on the new alternator) is correct one and in perfect condition? Also, where did you buy the belt?
Check the condition of the belt tensioner; you may want to replace the tensioner and the idler pulley(s). Not sure how many idler pulleys your engine has. N52 (on my car) has 2 idler pullies.

Originally Posted by pcy

Since you said the problem started after the alternator was replaced and new belt was installed, are you absolutely sure the alternator pulley (on the new alternator) is correct one and in perfect condition? Also, where did you buy the belt?
Check the condition of the belt tensioner; you may want to replace the tensioner and the idler pulley(s). Not sure how many idler pulleys your engine has. N52 (on my car) has 2 idler pullies.

I did check the pully was brand new the alternator had the same serial numbers as the original.. i got the belt from the same place i bought the alt from at BMWautoparts.com im thinking it was a defective belt because it didnt just break it was totally shreaded...

messed up,,,, bmaautoparts.com

Make sure your alternator is seated properly. Any gaps will set the pulley offline.

I don't know if its just me but installing the ac belt is harder than replacing the alt, waterpump, ect. Even with the special tool. Good thing I don't have to do it again, drive it till it snap then I will change it.

Originally Posted by v8power

Make sure your alternator is seated properly. Any gaps will set the pulley offline.

I don't know if its just me but installing the ac belt is harder than replacing the alt, waterpump, ect. Even with the special tool. Good thing I don't have to do it again, drive it till it snap then I will change it.

I checked that out and the alt was nice and tight to the bracket. Don't wait till ur belt snaps cause it can damage a hose or somethin like wat happened to me,

I'd like to know how a broken drive belt can damage a water pump. Maybe it needed to be replaced for other reasons, but because the belt slapped it? Come on.

Originally Posted by Stephen Max

I'd like to know how a broken drive belt can damage a water pump. Maybe it needed to be replaced for other reasons, but because the belt slapped it? Come on.

The belt just didnt break and flapped around and fell off. It winded around the back of the pulley.. and caused it to leak. it was also winded around the tensioner too. the wierd thing is how the belt fell apart in strands,,, its like it unwinded and wraped around everything ,,, i really think it was a bad belt.. another thing is,, that it also took out the a/c belt too.... None of the hoses were cut or damaged like i first thought was why i lost coolant,,,, water came out of the water pump.. i decided to change the upper and lower hoses cause they are the original ones and felt it was time. Im still scratching my head on how that happend.. could not pin point... WTF the deal was.. the first error i got was a low coolant ,,, then a sec later i got a overheating turn car off. i pulled over faster than u can say WTF !! and shut the car off.....( im really dumbfounded on this one...) Everything is pointing at a defective belt.. and im changing all the pulleys just to make sure it dont happen again..... and ease my mind

let us know how everything goes after changing those parts.

Originally Posted by pcy

let us know how everything goes after changing those parts.

Will do Bro.... should have the car back monday... tuesday latest.

Originally Posted by pcy

let us know how everything goes after changing those parts.

Well have my car back. and all is good .. everything pointed to one of the two belts breaking .that caused both to break.. the strands from the belts were wound so tightly around the water pump shaft it jacked up the seal and was the cause of coolant leaking .. So i ended up replacing upper and lower hoses,, thermostat. water pump. coolant sensor. tensioner, idler pulley,, and also my mechanic installed a tensioner for the a/c belt Too ,. A + !! ( said theres an update ) i didnt know he did that,,, till i picked up the car yesterday... so one good thing became of my mishap...

Again,, i wana thank all who posted ur help and concerns for my car,, u guys are,,,,, da Best ! and what makes this site so freakin Kool ,,,,,,

Originally Posted by H F

Well have my car back. and all is good .. everything pointed to one of the two belts breaking .that caused both to break.. the strands from the belts were wound so tightly around the water pump shaft it jacked up the seal and was the cause of coolant leaking .. So i ended up replacing upper and lower hoses,, thermostat. water pump. coolant sensor. tensioner, idler pulley,, and also my mechanic installed a tensioner for the a/c belt Too ,. A + !! ( said theres an update ) i didnt know he did that,,, till i picked up the car yesterday... so one good thing became of my mishap...

Again,, i wana thank all who posted ur help and concerns for my car,, u guys are,,,,, da Best ! and what makes this site so freakin Kool ,,,,,,

Since the N62 in the 545i has a stretch belt for the A/C, and sounds like you added a tensioner to the block like the 745i has - what is the new belt P/N?

Hogie,,, ,, I will call my mechanic and get the part number for u.....

Originally Posted by Hogie

Since the N62 in the 545i has a stretch belt for the A/C, and sounds like you added a tensioner to the block like the 745i has - what is the new belt P/N?

Hogie ,,, here is the part. Number , it's a Continental CONTITECH 4pk860
Sry I took so long ,,,

Originally Posted by H F

Well have my car back. and all is good .. everything pointed to one of the two belts breaking .that caused both to break.. the strands from the belts were wound so tightly around the water pump shaft it jacked up the seal and was the cause of coolant leaking .. So i ended up replacing upper and lower hoses,, thermostat. water pump. coolant sensor. tensioner, idler pulley,, and also my mechanic installed a tensioner for the a/c belt Too ,. A + !! ( said theres an update ) i didnt know he did that,,, till i picked up the car yesterday... so one good thing became of my mishap...

Again,, i wana thank all who posted ur help and concerns for my car,, u guys are,,,,, da Best ! and what makes this site so freakin Kool ,,,,,,

Good to hear you are back in business!
Refreshing the coolant system was a good move. You should be good for another 60-70K worry free miles now.
I am going to try that AC belt tensioner also. That would make life a lot easier.

Originally Posted by bimmerfan52

Good to hear you are back in business!
Refreshing the coolant system was a good move. You should be good for another 60-70K worry free miles now.
I am going to try that AC belt tensioner also. That would make life a lot easier.

Thx ,,,,, I'm so happy to have my baby Rollin again,..
I also changed the brake fluid , pwr steering fluids 6 months ago I changed the alt bracket gasket , tranny pan , oil pan gasket , valve cover gasket ,front timing cover gaskets, MAF Sensor, and now goen on 5000 oil change incriments , and tranny fluid every other year
I swear,, ,,,This dam car is burnin a hole in my pocket ,, but does not overweigh the enjoyment I get when I drive it,,, so yes,,, another 70,000 would be a nice ,,
Bimmer fan ,,,,, I've learned more about my car in the last 6 months of activley being on this site , with information posted from guys like u,,, thx for being a good information resource,,,