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01-30-2018, 09:17 PM | #1 |
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N55 serpentine belt tore off
The serpentine belt in my 2011 N55 equipped 135i with 38000 miles tore off the other day.
There was no real damage to the belt at all, no contaminants on any of the pulleys. I didn't see any oil leaks on the engine (under tray was clean). I got no warning of any kind (no squeaking etc) - it just tore off. The only indication something was wrong was a slapping sound (which was the belt smacking on various things in the engine bay). I noticed it just as I pulled into my garage. When I took off the plastic intake bit at the front and surveyed the damage, a large percentage (maybe 60%) of the belt was missing and whatever remained was holding on by a thread. Significant portions of the belt have gotten sucked into the fan as well, they were wrapped around the blades but luckily nothing broke. Quite a bit of the belt had wrapped itself around the alternator pulley. When I pulled out the radiator fan and removed the under body protection, there were pieces of belt everywhere in the engine bay (both rubber an thread). I've since replaced the belt and tensioner, everything seems fine now. The fan runs without issues as well (I was seriously concerned it had become un-balanced since it took a beating when the belt was thrown into it. I inspected the broken belt very closely. The sections of it that are intact appear to be in very good condition - the belt isn't compromised or cracked or anything. Just wondering what could be the cause of this.. I'd hate for this to happen again and strand me or worse... destroy the front main seal. |
01-31-2018, 04:41 AM | #2 |
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I was talking to a mechanic the other day at a tech session and he said this is not uncommon. It's due to the failing tensioner pulley. He said the most bizarre case of this he had seen was as the tensioner was failing and was causing the belt to eat away at the crank seal. The seal failed and the belt was wrapped around the crank and drawn into the block. Strangest thing he's ever seen.
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hunginator162.00 |
01-31-2018, 05:19 AM | #3 |
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What fails on the tensioner pulley? Does it cause the belt to mis-align slightly causing heat (and wear)?
My tensioner pulleys are slightly melted (one more than the other), but there was nothing obviously wrong with the tensioner when I pulled the old one out. The old tensioner's rubber gasket (The one that goes between the bolt and the engine block) had completely failed and was in pieces. It was still tightly secured to the engine though... so it's not like it was loose or rattling around or anything - and it definitely wasn't at max tension either. Keen to get to the bottom of it to see if there's anything that can be done to avoid a repeat of this. |
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01-31-2018, 05:52 AM | #4 |
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According to the techs I've spoken to, this is not uncommon on the N5x engines. As noted in post #2, the potential effects are catastrophic. As the pulleys - tensioner or idler - are the usual cause, the general recommendation is to check for any displacement of the belt on the pulley at every oil change. If the belt is not 100% centered on the pulleys, replace it, the tensioner, and the pulleys immediately.
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01-31-2018, 06:23 AM | #5 | |
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01-31-2018, 09:08 AM | #6 |
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Tensioner and idler pulleys. The kits normally include the tensioner with pulley, the idler pulley, and a new belt. Sorry for the poorly-worded statement.
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01-31-2018, 09:29 AM | #7 | |
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From owning E30s in the past, I typically get all my maintenance stuff to the house first, so I can tackle multiple projects at once and not have to stop in the middle. |
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01-31-2018, 10:27 AM | #8 |
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The post about the belt being sucked through the main seal into the engine is relatively common as far as I know. There are other reports of that happening online. I think root cause of the failure is it's 7 year old rubber. And not just a rubber bushing - the belt is constantly bending and flexing as it goes around the engine. You're asking a lot of that belt. Mileage interval is 60k but there may also be a time limit as well. Maybe 5 years? You're at 38k miles - if you're on the factory tires, this may be an indication you want to change those too.
Now that I'm done preaching about proactive maintenance, I'm going to drive my 2011 128i that's still on the factory accessory belt. I've got the kit in the garage, just need to get it done to avoid getting stranded or damaging something. |
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01-31-2018, 10:35 AM | #9 |
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ECS sells a complete kit.
https://www.ecstuning.com/b-genuine-...11287582946kt/ Total of four pulleys. I should do this soon. One of my pulleys makes a squeaking noise for a couple minutes on cold start. |
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01-31-2018, 03:23 PM | #11 |
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Does someone have a picture or diagram of this? When I shut off the motor, I hear a quick squeak right before everything stops. I have 35k on my 2013 135is.
-Sam |
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01-31-2018, 04:17 PM | #12 | |
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Wanted to add, I only hear the squeak when it's very quiet, like at nighttime in my garage when I've just pulled in and shut the car off. |
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01-31-2018, 04:53 PM | #13 |
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Some guys with early N54's had this issue... it ended up being how the car was being driven... or shall I say LAUNCHED!
Some drivers were launching so hard that the rear axle would "hop". This "hop" would let the front crankshaft pulley contact the radiator support... some belts would get shredded or cut. The fix was a new front crankshaft pulley which was not cheap! I would take a real good closeup look at your pulley. IF you have a laser pen... that might help see IF everything is in correct alignment. Dackel
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01-31-2018, 05:07 PM | #14 | |
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Like I said, I've noticed the squeak for almost 4 years, had it serviced several times since then, everything is A-OK. I have an N55, btw. |
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01-31-2018, 05:07 PM | #15 |
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This is my first BMW, that is, first one that I’ve kept for so long. I’ve got plenty of other cars in the fleet, none of them have had such a catastrophic failure of the belt with no warning.
The belt IS inspected, at least bi-yearly along with my oil changes. No damage of any kind was apparent at last inspection, which was just 5 or so months ago. And it’s not like this is a highly specialized component. Virtually every car out there has a serpentine belt, tensioner and pulley. Although I suppose a lot of the cars these days have gone electric for steering. Just another cost to pay for owning the Ultimate Driving Machine. I’d advise people with cars 5 years old or more to just change the parts out. I ordered my replacements from Pelican Parts. They have parts from oem suppliers if you want to go that route. Instructions on how to do this job are here: https://www.newtis.info/tisv2/a/en/e...ement/CyzmXfQq There are two pulleys on the tensioner itself. There are two other pulleys there also. Then it goes around the alternator, power steering pump and of course the crank pulley. Getting the fan off was a bit of a pain since I’d never done it before. There is one self-tapping torx screw on the underside of the fan that holds on transmission cooler, so I had to remove that before the fan could be lifted out. |
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01-31-2018, 05:16 PM | #16 | |
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Plus after a very long drive(say over an hour or so) on a very hot day... when the ac is on and I am driving under very little load... say 2nd gear at 2,700 rpms... when I lift off I get a wurring type sound. Its hard to describe. I think its the rear crankshaft seal.... that was more of a problem with 1M's... but it also effects the 135i's too. Our cars make so many weird noises.... from the noisy direct injection at idle(very diesel like sounding) to the noise from the trans/clutch when switching the car off(I just keep my clutch pedal depressed, and whala no noise!) to the fax or inkjet machine noise when unlocking the car... really our cars make so many noises.... it just don't bother me anymore. The only thing that matters to me is the sweet noise coming from my PE and the incredible throttle response(& tq!) at very low revs. The 135i is truly a giant killer on back roads or the autobahn. I love this platform. Dackel other belt threads... My Belt decides to rip and get caught in my radiator fan. http://www.1addicts.com/forums/showthread.php?t=524591 Help! Shredded 4 serpentine belts in 100 miles. http://www.1addicts.com/forums/showthread.php?t=1104374 Broken Serpentine Belt... http://www.1addicts.com/forums/showthread.php?t=565322 Shredded serpentine belt http://www.1addicts.com/forums/showthread.php?t=1063860
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01-31-2018, 05:45 PM | #17 | |
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01-31-2018, 06:38 PM | #18 |
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wow, this is much more prevalent than I thought. Just pulled the trigger on 2 of these...
https://www.ecstuning.com/b-conti-te.../adk0022p~crp/ Couldn't quite take the $300 for OEM, so this is a less pricey alternative. At least this gets me some piece of mind for a while. The down side to this is it's only 1 idler and 1 tensioner. |
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01-31-2018, 08:31 PM | #19 |
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Here are some links to hte parts.
Belt: http://www.rmeuropean.com/Products/1...G21-V5158.aspx Tensioner: http://www.rmeuropean.com/Products/1...G40-V5158.aspx And if you want to change the other pulleys too (I didn't) http://www.rmeuropean.com/Products/1...G40-V5158.aspx and http://www.rmeuropean.com/Products/1...G40-V5158.aspx |
01-31-2018, 08:35 PM | #20 |
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Here are photos of my tensioner. I didn't find any damage on any of the other pulleys.
In addition to the slightly melted pulley, there is a rubber o-ring in between the bolt that goes into the engine and the engine block itself. That had completely dried out and was brittle like plastic. Fell to shreds as soon as I took off the tensioner. Not sure if that was the cause or what. |
02-01-2018, 01:09 AM | #22 |
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There’s nothing to it man. I was really concerned when I did mine but it was easy. Just need patience. Don’t force anything (too much).
- remove upper intake pipes https://www.newtis.info/tisv2/a/en/e...lement/Hm4jdid - if you have DCT, remove under body protection https://www.newtis.info/tisv2/a/en/e...ement/AlpHh5nD - remove the single torx screw that holds on the transmission cooler https://www.newtis.info/tisv2/a/en/e...lement/HEzhiPa - remove the screw at the top left of the radiator fan (as you face the car), unplug the power connector and pull up to remove. Pay special attention to the various clips. There is one clip on the opposite end of where the torx screw is about halfway down. One which clips into the cowling and the other which clips into one of the intercooler pipes. https://www.newtis.info/tisv2/a/en/e...lement/HEzhiPa |
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