nightkrawler

valkman, did you change the flywheel bearing also?

heres both screens

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watchme

After reading this thread and paying attention to what everyone has tried, the mechanic in me keeps going back to the harmonic balancer.

Nightkrawler...you mentioned taking the belts off and looking at the balancer turning. Did you pull the balancer and look at the condition of the rubber sandwiched in between the inner hub and outer ring of it? It tends to crack over time and the slightest misalignment or exagerated movement will cause vibration.

Now...I'm not BMW tech...so I don't know the construction of the M5 balancer. Most balancers have the rubber but some are actually fluid-filled, i.e Fluidamper. If our balancers are fluid-filled, just watching them spin on the engine would not be sufficient to diagnose a problem.

Hope it helps.

Apeman

According to my theory, that B1 exhaust result is only just within accepted limits and could well cause some slight issues. As you can see, both the advance and retard values have shifted symmetrically towards retardation by around 3.5 degrees compared to the other test results.

Sorry for not digging in the archives, but have you already had Vanos work done on the B1 side? If you allow some purely non-fact based speculation, the two thoughts that come into mind are that either your B1 top chain or tensioner are somewhat tired, or there may have been a slight timing error when working on the B1 Vanos. The main chain would appear to be just fine, as there is no clear shift between the B1 inlet values and the B2 values.

Valkman

If you mean the ball bearing at the crankshaft end, answer is no. Actually I thought about it, but after feeling the bearing spin freely without any play, I didn't think it was necessary.

watchme's comment about the damper is really interesting. I've thought about it over and over and know the construction of the damper and how it can look fine, but still be bad. I haven't yet took my into closer look, but might do that soon.

nightkrawler

anything is possible and im considering all input. i removed only the vanos adjustment units. it is not necessary to mess with the timing, the valve covers never even come off. i've noticed when i sit in the car during the vanos test it makes a vibration which feels similar to the one we have, so it could be a possibility. however it dosent explain the associated woo-woo-woo-woo-woo noise. im leaning tword something tword the back of the engine. it definitely sounds like it is from something rotating. valkman, prehaps the brand new flywheel has the same issue?

i didnt take the crank pulley off to check the damper. i should have so i will do it this weekend. afaik it is not fluid filled.

Apeman

*copied from the poll thread by request*

For my car, the vibrations can be felt (well, at least I can) through the seat, wheel and shift lever. For me, the easiest way to show it to other people is to open the front door wide and grab the edge; the door will transmit and amplify the vibrations quite nicely.

As I've said before, I think if the exhaust would be 100% properly damped the vibrations wouldn't be as noticeable (but probably still there). I have had a friend look at and feel the engine, and the engine itself doesn't seem to be vibrating hard enough to be the sole cause of this phenomenon. Together with the vibrations also being audible in the exhaust note, I've drawn the conclusion that the vibration is mainly magnified through resonance in the exhaust. This to me is also one of the reasons why you would feel the vibrations more clearly when standing still; there will not be any countervibrations from the car moving.

When I bought the car I didn't notice any vibrations, but they developed fairly soon afterwards. At around the same time, the MAF readings started dropping and the car developed a slight torque loss in the extreme high and low rev ranges (mid range is fine). I have had the exhaust adjusted once (for rattling/knocking when driving on bumpy surfaces), but I don't think they actually replaced any of the supports. I may request that at some point, but first I want to get the engine into top running shape to see how that affects things.

YamahaR1

check the rubber mounts on your exhaust. unlike other cars, our exhaust doesnt "hang" it rest on cross members, when the rubber mounts go bad, you can feel a vibration on the shifter and under the seats. Unfortunately thats not the vibration we are talking about. we are refering to the vibrations from the engine at low rpms. the way i tested mine was by placing a jack under the exhaust to lift if off the cross members.

nightkrawler

sounds to me like he has the same vibration as we do, everyone explains it a bit differently. i remember reading a thread here where a guy had a similar vibration and it turned out to be rod bearings. i really hope this is not the case with us.

koolmofo

In addition to the vibration, what we are talking about here is the sound that seems to eminate from the drivers side of the engine compartment (US models) and is linked to the RPM range starting at about 2000. Has anyone been able to make a recording of the sound. If so, can you please post, so that we can all compare.

Apeman

I think my vibrations also originate from the engine, but are magnified by the exhaust. Obviously I'm not 100% certain whether we're talking about the same vibrations, but my guess is we are. The exhaust rattling I was referring to was a completely different problem, just mentioned that because it proves that there definitely was/is some structural problem with my exhaust mounts.

I think with my car these issues are so tiny that the guys at the dealership don't even consider them problems. I've had various mounts checked a number of times and they haven't found anything. It seems like the car has to be very clearly broken for them to really find something, simply worn bits don't really register. As a result, I've kind of learned to live with these things since it seems I can't get them fixed anyway.

Just so that we're clear, the vibrations I'm referring to can be found in a couple of narrow "zones" between 1k and 3.5k rpm, and can mainly be heard/felt when the car is stationary in neutral gear.

For those of you who can hear or feel vibrations, could you try to estimate the frequency of the vibrations? This could help us determine the cause. Maybe someone with better understanding of engines and drivetrains in general and the S62 in particular could assist in troubleshooting?

For example, it seems to me that a broken flywheel would probably cause vibrations at the same frequency as the crank speed. The same would go for bad rod bearings. At least for me the vibrations I'm having seem to be half the crank speed (it's easiest for me to count the vibrations around 1200rpm). I don't know whether this could indicate issues with one of the camshafts?

One comment regarding the video that koolmofo posted: for that one the frequency of the drone correlates fairly well with the rotational frequency of the tires, and fairly poorly with anything else. One possibility could be that what you hear there is a tire imbalance inducing a drone in the exhaust note. Here are the maths:
At approx. 2200rpm he's doing an indicated 23mph, say 21mph actual speed; this corresponds to ~9.4m/s. With the circumference of a 275/35/18 tire being ~2.04m, this will give you a rotational frequency of 4,6Hz which is pretty close to what you're hearing in that video. For this to be related to the engine, even a fourth of crank speed would still be ~9Hz (2200/60/4) which is definitely higher than the drone you're hearing in the video.