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My E90 just started making some belt noises last night, I opened the hood this morning to find that the belt tensioner is slowly walking the drive belt right off. I figured I'd try to tighten the tensioner back on a bit after re-setting the belt in place only to find that my belt tensioner has no way to tighten the bolt. It's got a flat surface where the aluminum torx bolt should be. Now I'm wondering if this is too dangerous to drive to the shop tomorrow because I'm worried the belt will remove itself from the crooked tensioner and damage something. Has anyone seen something like this?
 

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The tensioner mounting bolt has snapped. Belt tension is the only thing holding the tensioner on. Use a T60 socket on a big wrench to remove the belt tension, and remove the belt. Then the tensioner will fall off.
 

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Nuclear engineer
02/2012 X5 35d M57Y CPO 99K miles NOKIAN WR G3 12K miles
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Interesting aluminum alloy marking ***8220;AlSi9Cu3***8221;; 88% aluminum, silicon 9%, copper 3%, a Silumin casting evidently. Noted to be susceptible to corrosion. I wonder what is the proper screw fastener material?
 

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My E90 just started making some belt noises last night, I opened the hood this morning to find that the belt tensioner is slowly walking the drive belt right off. I figured I'd try to tighten the tensioner back on a bit after re-setting the belt in place only to find that my belt tensioner has no way to tighten the bolt. It's got a flat surface where the aluminum torx bolt should be. Now I'm wondering if this is too dangerous to drive to the shop tomorrow because I'm worried the belt will remove itself from the crooked tensioner and damage something. Has anyone seen something like this?
Welcome to the forum Luke!

As relative4 states, do NOT drive the vehicle, or even run the engine at idle, with the tensioner attachment bolt broken that way, as you will almost certainly have the belt walk off the pulley and get shredded, causing a "whole 'nuther can of worms." :)

Be VERY CAREFUL releasing tension on the tensioner by rotating it at the T-60 opening, and protect yourself and the radiator fan, etc. from flying parts/tools if the tensioner slips forward off the remaining bolt stud.

BTW, have you had the Breather Heater Recall performed yet? Recently?

Please let us know how it goes,
George
 

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The breather heater and all other recalls have been taken care of recently so it shouldn't be that making the noise. As it sits, the tensioner pully is out of alignment and the drive belt is rubbing on several components, as well as itself. I will probably have it towed to a shop and hopefully they don't have too many issues with removing the weird bolt. I was just hoping to see if there's any way to tighten it back in place so I could avoid the tow. But that doesn't seem possible or safe right now.
 

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if Y'all think its a good idea to try to replace the belt tensioner myself, I might give that a go. I just don't have the tools I need with me to properly replace the tensioner pully (i.e. torque wrench, socket extensions, torx bits) I think I'll price out all that stuff at my nearest auto parts store plus the uber ride cost and see if it is indeed cheaper to replace the pully and drive it there, or simply pay for a tow. It would be smart to have some more tools at my place for this car, I'm just a bit apprehensive because I've spent a lot of money on tools trying to repair my various cars over the years and most of my tools are away in my parent's house.
 

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02/2012 X5 35d M57Y CPO 99K miles NOKIAN WR G3 12K miles
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Some BMWs have a Safety Recall on Belt Tensioner Pulley Bolts.
 

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Discussion Starter #9 (Edited)
looks like the recall for tensioner pulley bolts is only for the X5. No stores in my area carry the tensioner assembly including the bolt. I'm most likely going to have them replace it along with some service items when I take it in. Still sucks I have to bring it in on a flatbed just because of a piece of aluminum broke, but it could be much worse. Apparently it's a fairly common issue where the bolt breaks and the belt slowly walks off the tensioner. I'm pretty lucky however, because in my case I caught it right before it fully came off. Sometimes the belt comes off from the tensioner without anyone noticing and subsequently digs itself into the crankcase main seal, resulting in belt material in the engine oil and no oil pressure. So I cant complain too much. Thank you for all the help everyone. at the very least I now know what to tell the mechanic once it makes it to a shop.
 

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Welcome to the forum Luke!...BTW, have you had the Breather Heater Recall performed yet? Recently?
The breather heater and all other recalls have been taken care of recently so it shouldn't be that making the noise...
Reason I asked about the Breather Heater Recall, the dealer tech has to remove the serpentine belt (release the tensioner where the bolt head is snapped off) and remove the Alternator to access the Breather Heater & replace it. See the attached RCRIT that describes the recall procedure, beginning on p.7 of the pdf.

HOW did they miss/break that bolt head? How long have you had the car & who was working on the front of the engine last?

That bolt head didn't just fall off on its own. SOMEONE torqued it improperly. See this procedure for replacing the Tensioner:
https://www.newtis.info/tisv2/a/en/...lt-with-tensioning-deflecting-element/GWZWYpu

As you should already know, any bolts that are inserted into threads in the Magnesium Alloy Crankcase (as this one) are aluminum, are SINGLE USE, and if released must be replaced with new and torqued EXACTLY as stated in the BMW Specs, such as this one for that Tensioner Bolt (FIRST line, 1AZ):
https://www.newtis.info/tisv2/a/en/...lt-with-tensioning-deflecting-element/5zZggtG

If any questions, please ask before someone causes you/your vehicle MORE damage.

George
 

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Discussion Starter #11
that hadn't occurred to me. That belt tensioner bolt shouldn't have had any reason to break off like that from my normal driving to work and such. I had assumed that it happened yesterday because the belt had just begun to squeak. however it probably took quite a few miles for the drive belt to walk its way off the pulley as it was only slightly agar. I'll be sure to mention this to them once I bring it in. however I will have to wait another day with no car if I bring it to the dealership because they're booked until Tuesday. Perhaps it would be worth it if they'll be willing to take care of some of the charges for the other services done on the vehicle. I'll be calling the service dpt. up tomorrow to see if that's a possibility.
 

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well the dealership informed me that they would not be covering any of the parts or labor for the tensioner or bolt despite being the last place it was worked on. No surprises there.
 

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well the dealership informed me that they would not be covering any of the parts or labor for the tensioner or bolt despite being the last place it was worked on. No surprises there.
Amazon Prime is your friend -- see below -- get parts tomorrow for <$120 :)

I didn't mean to imply that you could "absolutely prove" to whatever standard of proof: "reasonable certainty", or "more likely than not" (>50% likely) that the dealer's tech failed to reasonably inspect, or actually broke that bolt by re-torquing. The point is that anyone in business should be trying to maintain "Goodwill" for his business. The dealer should understand that if a customer has reason to believe that his shop made an error, or failed to reasonably inspect a part involved in the recall, even if just to turn the Tensioner to remove the belt, then his response to your complaint should NOT be totally dismissive.

In this instance, as a DIY type, I can't really see any reason for the dealer to offer to supply new parts at no cost to you, or to offer free labor. About the best that one could reasonably expect is some discount or expedited service in realization that failure to reasonably inspect and advise of that condition when the car was being serviced in the recall has resulted in another trip to a shop on your part.

Another reason to DIY. You can get a kit to do the replacement of the tensioner, belt & idler for ~ $100. NO towing, NO labor if DIY. It would be cheaper to rent substitute transportation for a week (while parts ship) than pay someone else. If speedy delivery at reasonable prices is what you need, Amazon Prime will get it to you tomorrow for <$120:
https://www.amazon.com/ContiTech-AD...-2-fkmr3&keywords=bmw+N52+serpentine+belt+kit

Need Tools?: Neiko Torx bits kit, including T-55 & T-60 for tensioner; 1/2" breaker bar to turn T-60 for tensioner release:
https://www.amazon.com/Neiko-10071A...&qid=1550514984&sr=8-5&keywords=t-60+torx+bit
https://www.amazon.com/ABN-Extensio...d=1550515235&sr=8-17&keywords=breaker+bar+set

Here are other (slower delivery) alternatives:
https://www.ecstuning.com/BMW-E90-328i-N52_3.0L/Search/SiteSearch/serpentine_belt_kit/

Harbor Freight Tools is a cheaper source if you have a local store, but shipping takes week+.

Please let us know how it turns out,
George
 
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