M50, Vanos + performance cams = problem ??

[Sezam]

Hello everyone.
I’ve just registered on your forum to check if possibly anyone of you may have some experience with performance camshafts and accompanying Vanos rattle in M50 engines.

Basically my M50B25 engine has been rebuilt and a little modified over half year ago and since then my Vanos unit makes terrible noise in between 1800 and 2200 RPM.
Also since that time I’ve been doing everything I can to get rid of it, spending (probably unnecessary) lots of money and I am failing it.

So I thought that perhaps someone here would give me some advice.

Now, some more details.
Nearly all if not all of the parts in the engine are new at the moment. The engine capacity has been increased to 2860 ccm and Dbilas Dynamic performance cams (http://dbilas-dynamic.de/dbilas_eng/index.htm) are used.
At first after the rebuild, the oil pump, chain tentioners and the Vanos unit were old, not replaced.
Everything was perfect after the job except for as I mentioned earlier, the Vanos was making noise that I cannot live with.
So I started to look for the cause of the rattle. First we replaced the Vanos diaphragm spring. It not helped, so we replaced the whole Vanos unit (not for a new one though), not helped either. We started to look for a problem somewhere else, we replaced the oil pump for brand new, replaced the chain tentioners, replaced the sprocket with helical gear and the helical gear shaft for a new ones. Nothing helped.
Then I found http://www.beisansystems.com website, where I found a sentence which I thought clarified my problem. The sentence was saying: “Note: M3 cars and cars with aftermarket performance cams (Schrick) must have no bearing axial play and bearing should have resistance to rotation (pre-load) to achieve optimal results”. There was indeed an axial play on my old Vanos unit, so as soon as possible I purchased the rattle and seal kits from Beisan Systems and repaired my original Vanos unit. The axial play on the splined shaft was eliminated completely. So I thought that this must help.
When we started the engine after the installation of repaired Vanos, is sounded promising, however after a few moments while accelerating and decelerating the engine speed the noise started coming back. I read on the package of the Repair Kit Ring, that the repaired unit gets its optimal performance after driven about 320 km in traffic, so we thought that maybe it’ll get better later.
Unfortunately, it didn’t. I’ve driven now much over 300 km since the Vanos repair and I think that the rattle is the same as pre-repair .
So I asked Rajaie from Beisan Systems for an advice on that, what he thinks about it. He wrote: “ ... the rattle is not so bad. I’ve heard much worst rattles. Yours is actually ok, especially considering the aftermarket performance (likely Shrick) cams. These are very aggressive and you can’t resolve the rattle completely” … . Not sure if my cams are very aggressive or not, but I think they are actually not.

So my question to you guys is, what you think about this? Have you got any experience with performance cams? Does Vanos rattle accompanies performance cams always? Is this normal and I should not worry about it?

You can also have a quick look at my engine rattle before and after Beisan Systems repair:
Rattle before the rapair:
http://www.youtube.com/watch?v=OAr2D4RbxnM (You’ll notice the rattle best on a small speakers or with bass turned off)

Rattle after the repair:
http://www.youtube.com/watch?v=X2Nu2zkKe7o

At this moment I am thinking of installing back my original camshafts to get rid of the rattle and actually make sure that this is the really cause. I am not very keen to do that though, as I know that the engine characteristic will change pretty much, I mean the engine performance will decrease ... 

I’ll be grateful for an advice.
Adrian

[Caligula]

Welcome to The Tech. Interesting build you have going, i would like to see more if you could post up in the Member Projects section. As im sure you know, all these cars have the problematic VANOS issues at some point in their life. I had similar, though not as pronounced issues with mine as well. Luckily i met Raj at Bimmerfest where he showed me a disassembled VANOS unit and his upgrade kits. As Raj described it, the issue becomes more pronounced as you increase the cam profile, like going from 325 to M3 cams, as it naturally creates more vibration and has more mass for the camshaft gears and connected VANOS to spin. Check out the article i made on this along with the youtube videos.

beisan-system-s-vanos-rebuild-kits-3738.html

Now did you just do the VANOS outer seal kit, or did you do the bearing ring upgrade as well? The latter definitely will help with larger cams. Also from your videos, the problem with these is that you really cant tell what direction the noise is coming from, what i hear most is what sounds like a pulley bearing. I would give the VANOS and the primary chain tensioner as the culprits though you say you have replaced those.

[Sezam]

Thank you Caligula for the answer.
I certainly will post some more details in the Member Projects section, just need some time for that.

Now, my question is if some of you have performance cams and do not have Vanos rattle at the same time.

I checked out your article. Am I right saying that in your case the BS bearing ring helped much, but did not clear the rattle completely? When watching your video after the Vanos repair, I have a feeling that there is still a little of the Vanos noise. Or I am too touchy?

I've replaced both, the seals and the bearing ring to the ones I've got from Raj.
When I put the Vanos together, I found that the axial play has been removed completely on the splined shaft. It was actually quite tight. At that time I was sure that this is it, that this will fix my problem. But unfortunately, after installing the vanos back I found that it did not help :-(

The only thing which I did not replace within the Vanos system with a new one is the splined shaft (the one with two helical gears, inner and outer).
Raj is saying that I cannot do more about it, but the thing is, that I am still not sure, if the noise is really caused by the cams (and in this case I should stop further investigation) or if there is some other problem that I cannot locate.

I did not replace the main chain tensioner as well. I did replace the top tensioner for small chain, also both chains are new. The noise is coming definitely from the top of the engine and sounds like it's coming from the Vanos unit, hence I was not considering the main chain tensioner as an issue.

The other thing I am wondering about is that when you get a new M3 engine, there is not rattle at all. I've replaced nearly everything and the noise is still terrible to me. Why ... ?