Shimming what?
Maybe the noise the the valves slamming shut with those super duper heavy springs.
Just maybe.
1996 332IS
Built 3.2
CES/Steed TS Precision 6466, spraying a "$π!℅" load of meth.
Technique Tuning 80# tune.
1/4 mile 10.84 @ 136.72
Your 1 and only stop for all your BMW performance needs
WWW.CESMOTORSPORT.COM
The valves will still be riding the closing ramp of the cam but that is an interesting thought. If you ever turn a cam by hand in the motor with no chain installed the cam will force itself to turn every 60 degrees as one pair of springs pushes on the cam lobes. I wonder if at certain rpm's the cam is accelerating slightly and putting slack in the vanos gears and then taking it up again. Kind of like trans gear rattle with a lightweight flywheel. This seams astronomically unlikely to me. But if I read the OP correctly it was the only thing changed when the noise started.
I helped a friend with an s50 cam swap, engine was quiet before and after had the same exact noise you are describing, you could out your hand on the front of the valve cover where the chains are and you would've thought the chains were touching the valve cover, after many "vanos rebuilds" he brings it to a local guy who is pretty well versed in bmw's, told him he needed the anti rattle shim for the intake cam, and the 3 or 4 wearable parts ofof the vanos system, engine quiet now.
Have a rattle in my engine too - not cold, only warm, and usually around 2.5k rpm - 4k rpm (higher I can't hear anything due to exhaust) and part throttle. Like, if I am slightly accelerating or decelerating, nothing. But if I am in that kind of latent area of part throttle cruisingish... I don't even have VANOS lol. Just been leaving with it but I want to figure it out eventually.
Its the heavy spring rattle.
1996 332IS
Built 3.2
CES/Steed TS Precision 6466, spraying a "$π!℅" load of meth.
Technique Tuning 80# tune.
1/4 mile 10.84 @ 136.72
Your 1 and only stop for all your BMW performance needs
WWW.CESMOTORSPORT.COM
Do you have an M50 intake manifold swap?,if you have its more likely coming from the manifold,after I did my m50 intake on my m52 I got the same noise that is right around 2500-3000 rpm,its a resonating noise ,at least in my case.
It seems like there was an iphone application that would pinpoint vibrations with the accelerometer and/or mic. Its been years though.
I do have an M50 manifold but it has been on my motor since I even turbo'd my stock M52, and since I put my built motor in... So highly unlikely that all of a sudden I would develop a resonance in the intake manifold out of the blue that was never there before.
Also the noise is VERY pronounced in the front valvecover/vanos area... you can hear and feel it there directly. Sounds do travel in an engine so it wouldn't surprise me if it happened to be somewhere else.
That said, I'm going to call my BMW dealer today to get a quote on a new set of discs, spring and bolts for the intake cam. If I'm pulling everything apart again, they're going to get changed lol
On my e36 after I swapped the intake mani it started to make a noise very close to that engine noise that you linked it here,and I have the same noise in my e30 m50 nv turbo,I hoped for you was the same and an easy fix as ignore it like I do?
I've got the same thing going on as well with my s50. Had a cracked head so I swapped in a m50nv head modded to fit vanos and since then I have a rattle in the valve train area similar to vanos rattle. So I Rebuilt vanos with besian anti rattle kit, noise still present. Bought a dr.vanos in hopes to resolve it, well it wasn't, so that was a waste of money. Still have the noise, I have around 20k on my built motor with the rattle going on and no issues. I'd definatly like to resolve the noise though as the sound drives me nuts, so hopfully you figure it out.
So apparently its more common then we thought.
Thats the good news, along with the fact that no one has ever had any failures as a result of it.
Bad news is that nobody has fixed it... Except for me when I swapped engines hahaha :P
Thats car repair 101. Duh.
The M50 guys fixed their issues by putting the late style VANOS plates and spring...
EVeryone else just seems to live with the noise or goes to a mechanic and they say it's normal.
I can't see how this noise is normal, it just sounds plain ugly.
Also I'm not convinced that it doesn't actually do anything performance wise... Maybe not at WOT, but at PT in certain areas of the map I can feel and see the car hesitate/jerk around and my MAP sensor confirms it. I believe it has to do with the state of the engagement of the VANOS... if it's just starting to engage, etc.
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