Coincidence, or deeper issue?

To summarize:

00 M52TU 156k, just got done doing tons of the most common recommended DIY's around here... Last items to go on were both tensioners (one alternator, one A/C), idler, WP, new belt...

1st drive: Warm-up, approximately 15 miles of spirited driving (gotta break them VANOS seals in)... Everything seems Kosher, park awhile, start up again, bearing in brand new tensioner pulley on alternator side starts chirping at idle. I know the culprit because I isolated the sound with a stethoscope. I go back in, take the pulley from the A/C tensioner and swap it over to the alternator side, leaving the A/C belt off temporarily until I get this figured out. Start up, golden... Purring like a kitten. Celebrate with another 15 or so miles of spirited driving, park for about 45 minutes. Start up again, bearing on tensioner on alternator side starts chirping AGAIN. Confirmed culprit with stethoscope...

Am I simply suffering an unfortunate mfg. defect, or is there something I'm missing which could actually cause tensioner bearings on the alternator side to fail in FIFTEEN MILES?

Grrr...

UPDATE:



Schaeffler Automotive Aftermarket GmbH & Co. KG are the INA people... I've sent an inquiry to them along with this pic, but would still be interested in any other thoughts on the matter.

You know, that just stinks. In other words, the bearings in two brand new pulleys failed within 15 miles? I wonder if there's some sort of pulley misalignment, putting an odd strain on the bearings. If possible, you might try holding a straightedge against the pulleys to see if they line up. If there's no alignment issue, it raises questions about the quality of the bearings. Are they from a reputable manufacturer? Did they come with a warranty?

Originally Posted by bobdmac

You know, that just stinks. In other words, the bearings in two brand new pulleys failed within 15 miles? I wonder if there's some sort of pulley misalignment, putting an odd strain on the bearings. If possible, you might try holding a straightedge against the pulleys to see if they line up. If there's no alignment issue, it raises questions about the quality of the bearings. Are they from a reputable manufacturer? Did they come with a warranty?

Yeah, replace OR refund, but it looks like I'm dealing with two completely different bearings here... Different part numbers, different color seal (that may just be cosmetic, but part #'s?).

Warranties are fine, but right now they're not helping me drive the car

I thought about the alignment thing, but remember these are just tensioners with the back of the belt traveling over a flat surface with no lip or grooves... Even if there were some kind of off axis load being generated, could it really be enough to cause failure in FIFTEEN MILES???

It will be interesting to see if I hear anything on the difference in those part #'s...

I agree the misalignment notion is a bit of a stretch. Along the same lines, and just as much a stretch, I'd make sure the tensioner on the alternator side (where the failures occurred, right?) is mounted solidly. I say this because even though it's two separate bearings, they both failed while mounted in the same location.

Originally Posted by bobdmac

I agree the misalignment notion is a bit of a stretch. Along the same lines, and just as much a stretch, I'd make sure the tensioner on the alternator side (where the failures occurred, right?) is mounted solidly. I say this because even though it's two separate bearings, they both failed while mounted in the same location.

Actually, if you count the ORIGINAL pulley, that makes THREE failures at that location. However, the first one obviously lasted longer than 15 miles, and, when it started to fail, I still drove it (didn't really realize how much I was pushing my luck) for probably another hundred miles before addressing (attempting to?) the issue. I don't think either of these last two would even make 100 miles...

I'm going to have a look at the alignment tomorrow and see what I can come up with...

More to come...

Oh, that's right. that's the third one in same location in a very short time. In that case, I'd go over that tensioner very carefully to see if there's anything irregular. Was the tensioner replaced with an OEM part?

It might be worth popping a seal off of the bearing on the two new pulleys & check grease fill. It is conceivable that the bearing manufactured failed to fill or underfilled the bearings. That would be the kind of problem that would be batch related.

Okay, here's the latest...

Not finding any alignment issues or anything else that would even remotely explain these bearing failures, in a fit of frustration, I went to the stealer and got another mechanical tensioner (I know, I know ). Not that you'd ever want to pay twice the price for something if you have a choice, it is worth noting Encinitas BMW here in SoCal STOCKS these things... Bet they're the only stealer that does, and they must know it, because they make you pay... They tried to get me for $115 and I was like, WTF??? That got it down to $88, but they weren't going any further... You can get OEM INA online for $49.00, but then, that's no surprise, is it?

Anyway, I bit the bullet, inspected the bearing on the new unit, BLACK grease seal with part# matching the original which came off the car. Installed, drove a good thirty miles with purpose and so far, it's purrrrrfect...

Now it's time to come clean

It seems to me I may have done this to myself by trying to opt for the cheaper fix... The failed pulleys were actually purchased on spur of the moment from AMAZON while I was making an unrelated purchase. At some point on another thread, bluebee (lol, surprise that) gave me the (Dayco) part number for the pulley only, sans the tensioning unit, and when I saw them on AMAZON, I figured a "Dayco No-Slack Pulley" was a "Dayco No-Slack Pulley", regardless of where it came from (provided part#'s match). Anyway, it's entirely possible (at this point it seems), that while these were obviously the correct pulleys in size and appearance, the bearings themselves may not have been designed for the application for which I was using them. I mean, they both failed in the same amount of mileage as if set on their own odometers.

Hopefully INA will respond to my inquiry at some point and shed some light on the difference between the two sets of bearings.

In the meantime, feel free to commence ridiculing me at will for purchasing e39 parts on Amazon.com

Haaahaaa, you dope! There. Now, when (not "if") I do something comparable, feel free to return the compliment. Seriously, this sounds like a promising conclusion. How many miles will it take before you stop wondering whether you solved the problem?

By the way, I'm guessing your sig never seemed more appropriate.

Originally Posted by bobdmac

Haaahaaa, you dope! There. Now, when (not "if") I do something comparable, feel free to return the compliment. Seriously, this sounds like a promising conclusion. How many miles will it take before you stop wondering whether you solved the problem?

Tacked on another 65 or so miles last night, at least 40 of which were on the 5 fwy doing 80+. As of this time, still quiet as a finely tuned mechanical mouse As great as this thing feels right now, I can't even imagine what it must have been like brand new. I may have been getting a little frustrated at times with the amount of time she was spending in dry dock since I got her, but after the e39 gods have been appeased, it only takes a quick jaunt down the freeway to forgive all sins, and in the process, turn any angst associated with the trials and tribulations under the wrench into pride in a job well done (even if it took a couple of attempts to actually get it "right")