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Discussion Starter · #1 ·
I have a 2000 M5 with 42,000 miles, and it developed an engine vibration from about 2800 RPM to 3500 RPM. I have read through all the threads that discussed the same issue.

My dealer, Classic BMW in Dallas, says that there are metal shavings in the oil, and they suspect a connecting rod. However, they cannot determine the exact cause without taking it apart, which will cost $2,400!

Of course, it is out of warranty. They have to present a business case to BMW NA once they have taken it apart, and then I am at the mercy of BMW NA.

For all of you who had this vibration, what was the diagnosis and the final outcome?

Thanks for your help.
 

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Discussion Starter · #3 ·
Michael William said:
No SES, no codes, no strange sound.?????????
Nothing at all, except the vibration. Based on all the threads I have read, it seems to be a mysterious problem. What concerns me is that there are metal shavings in the oil filter.
 

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Muditha said:
Nothing at all, except the vibration. Based on all the threads I have read, it seems to be a mysterious problem. What concerns me is that there are metal shavings in the oil filter.
Metal shavings in the oil would worry me too .........

Would love to know the outcome and what ended up happening to your engine.
 

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Discussion Starter · #6 ·
It was a rod bearing that was defective. BMW replaced the entire bottom half of the engine and the crankshaft. The car was out of warranty by six months and had 42,000 miles. Classic BMW of Dallas was fantastic, and they worked with BMW North America to make sure everything was done perfectly.

I know we read too much about bad dealers, but, here's a great example of a dealer that did everything correctly.

I have driven the car about 2,500 miles since the repair, and everything is fine.
 

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Muditha said:
It was a rod bearing that was defective. BMW replaced the entire bottom half of the engine and the crankshaft. The car was out of warranty by six months and had 42,000 miles. Classic BMW of Dallas was fantastic, and they worked with BMW North America to make sure everything was done perfectly.

I know we read too much about bad dealers, but, here's a great example of a dealer that did everything correctly.

I have driven the car about 2,500 miles since the repair, and everything is fine.
I'm pleased it's all fixed up for you, and that the bearing didn't totally fail before it got replaced :flag:

What I can't understand though is how a worn rod bearing would cause a vibration rather than a knocking / clacking noise?
 

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Muditha said:
It was a rod bearing that was defective. BMW replaced the entire bottom half of the engine and the crankshaft. The car was out of warranty by six months and had 42,000 miles. Classic BMW of Dallas was fantastic, and they worked with BMW North America to make sure everything was done perfectly.
Wow, quite the contrast to some experiences of others with bearing problems! :eek: Glad everything was handled so professionally and apparently without much hassle. :cheers:
Dave
 

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I've been curious..what are the resonance modes of the engine?

I'm sure those big chains, the cams, the crank and the arms themselves each all have a specific frequency where they are the least comfortable.

Every engine in the world does this. The question is, for the S62, what are those RPM's, or frequencies? The reason I ask..if they are known numbers, staying away from those RPM on the highway during long runs, may drastically (or in a minor way) increase engine life. It might only make me feel better. who knows. Or it may increase my paranoia, as they may be all overlapped in such a way that it is impossible to stay away from them. :1:
 

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KBK said:
I've been curious..what are the resonance modes of the engine?

I'm sure those big chains, the cams, the crank and the arms themselves each all have a specific frequency where they are the least comfortable.

Every engine in the world does this. The question is, for the S62, what are those RPM's, or frequencies? The reason I ask..if they are known numbers, staying away from those RPM on the highway during long runs, may drastically (or in a minor way) increase engine life. It might only make me feel better. who knows. Or it may increase my paranoia, as they may be all overlapped in such a way that it is impossible to stay away from them. :1:
Seems that 2500 rpm features prominantly in a lot of posts on this forum concerned with engine vibration.

Also I noted that this reference to the Tubi exhaust system specifically mentions a resonance at 2500 rpm. My guess is that 2500 rpm causes the engine to hit a resonant frequency within the exhaust pipes, which would probably create a bit of a standing wave, which would mean that gases wouldn't flow out of the engine quite so well. This may in turn make the engine feel lumpy at that same rpm.

http://www.beastpower.com/Merchant2...ode=TU-BE39M-EX&Category_Code=&Store_Code=BMI

'No resonance heard in cabin (slight resonance at 2500 RPM with the "Rumore Plus" version).


Empirically then, 2500 rpm and S62 engines in M5's seems to be a magic number.


:wroom:

edit : If you search around, you'll see that some Porsche engines have a similar harmonic at 3050 rpm which can be felt inside the car. The cure for that motor is to replace the front engine mount. I wouldn't be too surprised if changing the engine mounts in the M5 also cures the 2500 rpm vibration quite a few people seem to be getting.
 

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The frequencies will show up as the correct interpretation (educated eyeballs) of the dyno curves, is my understanding of the situation. What I mean is that the resonance points will show up as minor dips in the torque curve. Difficult to interpret on the best of days.

This is what I mean by 'educated eyeballs'. One would have to know exactly what they are looking at when interpreting the dyno charts, and the dyno chart analysis would only help someone who knows a terrific amount about engine design..and they'd have to be VERY educated about the exact engine they are looking at, as well.

Those 'educated eyeball' people tend to be rather steeped in the industry overall..and tend to have a name of sorts. And..to add..at that point, they can't just run around making comments to gearhead neophyites about products and designs they weren't directly involved in--and even less comments if they were involved..as the remarks tend to be taken out of context-the neophyite reader has no basis for value weighting.

Very much like in the Monty Python flick 'Life of Brian', where they scream.."Follow the Gourd!!"..."No, Follow the shoe!!"... and the two different groups run off religiously following whatever, based..on ..relatively innocent and meaningless remarks...all taken fully out of context and with severely incorrect weighting.

Politicians are masters at the art of letting this take place (or aiding and abetting it), to further their personal aims and agendas. As well as the newspapers and TV news folk....(corporate/political inteference in daily affairs of the general public) :3:
 

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KBK said:
The frequencies will show up as the correct interpretation (educated eyeballs) of the dyno curves, is my understanding of the situation. What I mean is that the resonance points will show up as minor dips in the torque curve. Difficult to interpret on the best of days.

This is what I mean by 'educated eyeballs'. One would have to know exactly what they are looking at when interpreting the dyno charts, and the dyno chart analysis would only help someone who knows a terrific amount about engine design..and they'd have to be VERY educated about the exact engine they are looking at, as well.

Those 'educated eyeball' people tend to be rather steeped in the industry overall..and tend to have a name of sorts. And..to add..at that point, they can't just run around making comments to gearhead neophyites about products and designs they weren't directly involved in--and even less comments if they were involved..as the remarks tend to be taken out of context-the neophyite reader has no basis for value weighting.

Very much like in the Monty Python flick 'Life of Brian', where they scream.."Follow the Gourd!!"..."No, Follow the shoe!!"... and the two different groups run off religiously following whatever, based..on ..relatively innocent and meaningless remarks...all taken fully out of context and with severely incorrect weighting.

Politicians are masters at the art of letting this take place (or aiding and abetting it), to further their personal aims and agendas. As well as the newspapers and TV news folk....(corporate/political inteference in daily affairs of the general public) :3:
My uneducated and non expert eye can certainly see something odd going on between 2500 and 3000 rpm in the torque data in this sheet :

http://activeautowerke.com/dyno/dynoplot/textdata/00_M5StockvsM5CAI.pdf

:)

In particular, there appears t o be a dip in torque output at 2700 rpm

"He's not the messiah, he's a very naughty boy"
 

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It could be a crank resonance, a intake resonance..or even a engine mount resonance. Each of them will/COULD create enough 'change' to create a small dip. In the case of the intake, I'd take a stab and say it's a 'flow resonance' that is creating a bit of 'resistance' to flow and thus dropping HP (it would double up as an HP dip?). The big question for the neophyte...is HOW MUCH change?

In the case of crank or engine mount vibration, it would cause side or torsional stressing..which would cut the 'gysroscopic' or inertial/rotational energy a bit. Both could be the reason. Or neither. See how difficult it gets?

I know a 'fair' bit about motional mass and resonance issues..as that is part of my job to know that..but I know very little about engines in the specific.
 

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KBK said:
I know a 'fair' bit about motional mass and resonance issues..as that is part of my job to know that..but I know very little about engines in the specific.
Any idea why a worn rod bearing would cause a vibration in a narrow rev range? I would have expected a knocking / clacking noise at all speeds, not a vibration at a particular engine speed.
 

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My best guess? For the same reason a wine glass has suceptibility to exploding at a given specific frequency:resonance.

Even a spring has a specific 'resonant' frequency. I'd expect that a given frequency gives the motional mass vs the 'pressure' vs the 'acelleration' of the given assembly the 'fits'.
 

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Just a few questions

Muditha said:
It was a rod bearing that was defective. BMW replaced the entire bottom half of the engine and the crankshaft. The car was out of warranty by six months and had 42,000 miles. Classic BMW of Dallas was fantastic, and they worked with BMW North America to make sure everything was done perfectly.

I know we read too much about bad dealers, but, here's a great example of a dealer that did everything correctly.

I have driven the car about 2,500 miles since the repair, and everything is fine.
Good to hear about your experience. If you don't mind I have a few questions. You see I have just gone down this long and expensive road and I would like to compare your outcome with mine, considering we are in the same state, I'll bet we have the same BMWNA rep.

My out of pocket expense will end up being about $4000. They did not replace the lower half of the engine because that would have taken the price to somewhere in the $15,000 to $18,000 range.

What was your cost and how long did this process take? My dealer has been most helpful, it was BMWNA that made them take the direction that they did. I have had two rods replaced, a ring job, eight rod bearings replaced, both main bearings replaced, the crankshaft polished and x-rayed, all new gaskets and associated fluids replaced. The cause of this problem was a spun rod bearing, perhaps two of them in cylinder #8 and perhaps #7.

BMWNA covered 45% of the costs which probably would have been around $12,000 retail. Retail prices are not being charged because of BMWNA's involvement. They claimed I had been running the car with low oil which in fact is not true and was never proven with any facts.

I like your results much better than mine. I have also been without my car for 2 months! How long did your repair take?

Thanks for the feedback and I am glade your experience was a good one.

Mark
 
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