95 M50 weird load dependent chattering sounds familiar to anyone?

[tgrandahl]

So, before I get into it. I know this is most likely a failed VANOS unit, especially because the engine has 240kMiles on it now without having a rebuild. However i am still suspicious of what this annoying chattering problem is for a couple reasons.

I have been hearing a chattering noise that is very load dependent for some time now. It can be quite loud at times to a point where you can hear it over road and wind noise when driving 80 on the highway with all the windows up.

The load dependent part is the main reason I am suspicious it could be more than a vanos failure. To my knowledge almost all vanos issues are present at idle and all RPMs.

I spent some time trying to record the noise during my normal commute when I hear it the most, basically when I first start driving and the car is cold. However before I recorded any videos I also added an extra pint of oil beyond the normal fill point as I have read this can help with the vanos problems.

It does seem like the chattering noise that bothers me has become less common since adding the oil which also unfortunately has made it more difficult to capture.

Anyways, I compiled some of the best clips I have of the noise. The best thing I have is the last clip which is a recording made by mounting my phone in a pelican case in the engine bay. There is some pretty clear vanos 'rattling marbles' sounds but also a very clear chattering at a few points.

I think my plan as of now is going to be to do a vanos rebuild (although I dont know to what extent yet) and see if the chattering noise goes away as well. But take a listen if you would and let me know if this chattering noise sounds familiar to you.

Tyler


http://youtu.be/INw-HzLcD9c

[tgrandahl]

Hmm, The more i listen to this the more I feel that the classic failed VANOS 'rattling marbles' sounds isnt actually real. I think its a result of something on the pelican case rattling around. I tried to isolated it as much as possible so I will check into this tomorrow. Regardless the chattering sound is spot on what I always hear and is real, but this marbles sound is not something that I usually hear running the car with the hood up perhaps the VANOS is somehow not shot...

[ahlem]

Try taking off your A/C belt and see if anything changes maybe the A/C clutch. I had this sound on my non-vanos 535 and it was the mechanical cooling fan about to give up the ghost.

[tgrandahl]

Hmm, yeah AC clutch is a good one. My girlfriends car had a similar rattle that was intermittent and it ended up being the AC clutch. Unfortunatley my car has no AC and the engine fan was just replaced. The chattering sound that I am noticing has been happening for long before I replaced the fan too.

Tyler

[632 Regal]

I wish I could offer a suggestion but I can't really hear the noise you're referring to and I also have no experience with vanos. You also mention that it seems to be load dependent, have you looked at the guibo? Might be a few things going on at the same time.

[Rustam]

Check the oil pressure, perhaps these are valve hydraulic lifters chattering.