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.

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 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 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

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.

Originally Posted by bimmerfan52

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.

i didnt remove the tensioner ijust locked it over and stuck a small screw driver in the hole to hold it... i did take a good look at the belt alignment and all looked good..the alt was nice and tight to the braket.. the belt didnt break it actually shreaded to pieces.. which made me think it was bad...i did keep the old belt and having the tools to repair.. in the trunk is good advice and will keep in the trunk at all times..from now on.... the problem was that it damaged a coolant hose and and lost coolant so was S.O.L..
Iwas do for a coolant flush and was goen to replace all my coolant hoses any ways. so im gonna take iit to my mechanic and change the pwr steering and break fluids. and let him change all my pulleys and put the belts on and b done with it, cause of work i cant wrench on it till the wekend. and i want my baby fix like right now..
So Bimmerfan thanks for the reply and the good advice

Originally Posted by bimmerfan52

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.

This is a bit off topic, but the N62 engine in the 745i has a belt tensioner for the AC belt. The 545i engine has the mounting provisions for the tensioner. I'm wondering why BMW decided to leave it off and if one could be retrofitted.

OP - are you sure you routed the new belt correctly?

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 Stephen Max

This is a bit off topic, but the N62 engine in the 745i has a belt tensioner for the AC belt. The 545i engine has the mounting provisions for the tensioner. I'm wondering why BMW decided to leave it off and if one could be retrofitted.

OP - are you sure you routed the new belt correctly?

Yes,,, I took pictues of the belt route before removing it ,and put it back on the same way

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,

Originally Posted by Stephen Max

This is a bit off topic, but the N62 engine in the 745i has a belt tensioner for the AC belt. The 545i engine has the mounting provisions for the tensioner. I'm wondering why BMW decided to leave it off and if one could be retrofitted.

OP - are you sure you routed the new belt correctly?

Very interesting question. I haven't seen the 745i underneath to compare the two. You would think that with the motors being the same there wouldn't be any drastic differences. I'll check realoem to see if it is a different belt.

And I have often wondered how the 745i alternator fits into the larger engine bay so the oil cooler can be accommodated. That stupid profile gasket under the alternator bracket on the 545i has bruised many a knuckle. I guess they didn't want to change the block casting tool so it could do double duty for both the 545i and 745i, but a solid plug in the 545i block in place of that profile gasket sure would have been nice.

Originally Posted by bimmerfan52

Very interesting question. I haven't seen the 745i underneath to compare the two. You would think that with the motors being the same there wouldn't be any drastic differences. I'll check realoem to see if it is a different belt.

Well, I just bought a 745i AC belt tensioner off of ebay for $25. So I'll be the guinea pig and see if it works.

Originally Posted by bimmerfan52

Very interesting question. I haven't seen the 745i underneath to compare the two. You would think that with the motors being the same there wouldn't be any drastic differences. I'll check realoem to see if it is a different belt.

And I have often wondered how the 745i alternator fits into the larger engine bay so the oil cooler can be accommodated. That stupid profile gasket under the alternator bracket on the 545i has bruised many a knuckle. I guess they didn't want to change the block casting tool so it could do double duty for both the 545i and 745i, but a solid plug in the 545i block in place of that profile gasket sure would have been nice.

When I had that stupid alternator gasket replace on my 545 the mechanic told me that if it was a745 he wouldn't have to remove the sub frame, cause theres a lot more space , and he had a 745 on a rack , and it's more roomy in the engine compartment . And funny u mention putting a solid plug, cause I thought about actually welding a plate on that useless hole,and seal it up for good,,,

Originally Posted by H F

When I had that stupid alternator gasket replace on my 545 the mechanic told me that if it was a745 he wouldn't have to remove the sub frame, cause theres a lot more space , and he had a 745 on a rack , and it's more roomy in the engine compartment . And funny u mention putting a solid plug, cause I thought about actually welding a plate on that useless hole,and seal it up for good,,,

Yeah, the N62 engine is ten pounds in an eight pound bag in the E60 engine compartment.

I was referring to a core plug (a hole in the block designed to remove sand during the casting process and plugged with a round plug during engine assembly). All core plugs I have seen are round and once the plug is pounded into the block the pressure of the dome shape in the round plug prevents it from coming out.

Given the unusual "T" shape of the hole in the BMW engine a core plug might not be feasible. But it is likely that BMW could have come up with some type of more permanent solution had they tried a little harder.

Originally Posted by bimmerfan52

Yeah, the N62 engine is ten pounds in an eight pound bag in the E60 engine compartment.

I was referring to a core plug (a hole in the block designed to remove sand during the casting process and plugged with a round plug during engine assembly). All core plugs I have seen are round and once the plug is pounded into the block the pressure of the dome shape in the round plug prevents it from coming out.

Given the unusual "T" shape of the hole in the BMW engine a core plug might not be feasible. But it is likely that BMW could have come up with some type of more permanent solution had they tried a little harder.

isn't that t shape hole in the alt bracket have somthin to do with an oil cooler connection ?? Like the 550?

Originally Posted by H F

isn't that t shape hole in the alt bracket have somthin to do with an oil cooler connection ?? Like the 550?

Yes, that is where the oil is picked up in the N62B44 engine by the oil cooler when used in the 745i, and plugged (very unsuccessfully) by the profile gasket held in by the alternator bracket when used in the 545i.

just wanted to update... so i ended up takin my car to the shop, mechanic said i installed the alt correctly ( whitch got my confidence back ) but couldnt figure out why my belt broke,, and my water loss was not a hose, when the belt shreaded it winded around the water pump,,, and damaged the pump and leaked coolant.... So new water pump and hoses, new pulleys .also pwr steering ,brake fluid change. and im back in the race. i just hope now that no overheated damage occures.,,, wanted to thank everyone who responded to my prblem.. Thanks fellas !! i really appreciated the help...

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