M52 Vanos Seal Replacement. Interesting Procedure.....with pics

[Dave M]

My friend owns an e39 525 touring (M52 douuble vanos). On cold starts the idle would bobble around and eventually it would stall. It would continue stalling until warm. Mileage was OK, but not stellar. We inspected/tested all the usual suspects (intake leaks, ICV, CPS, plugs, MAF cleaning etc.) with no success untill we stumbled upon a fairly common fault involving deterioration (shrinking and hardening) of the vanos piston o-rings and seals.

The story goes that BMW used a shitty rubber compound that shrinks and the pistons don't seal properly, thus affecting vanos operation and engine performance. If you head to the dealer, they will replace your vanos unit ($$$$$$$$$$$$$$$$), which will include the same crappy seals which will eventually fail again.

I've never seen a vanos unit before, but we purchased a set of seals for $65, a head cover gasket and few odd and ends and went to work. Before replacing the o-rings/seals, the pistons had noticable lateral movement inside the vanos unit. Following replacement, it was a squeeze to get them back in the unit. Five hours later, the car idles perfectly and mileage has improved.

Is this a problem on the M50s???


Double mint vanos-less complicated than I expected. One of the seals is removed on the exhaust piston.


Vanity shot. No mistaking the front of that timing cog.

Just thought I'd share,

Dave

[KevinGoFast]

Hehe. Damn, I don't know.

[Dave M]

Hehe. Damn, I don't know.

Kevin,

It was a green touring with tan interior and winter package. Time to get off the crack.

Dave

[Bill R.]

good writeup on it on their site as far as the procedure and the symptoms, they have them for double and single vanos engines , here's a link... although i'm pretty sure your friend had to have gotten the seals from them anyway since nobody else is selling them that i know of. Except dr. vanos , but his kits are the whole unit i think.

anyway a link to the site and the procedurehttp://www.beisansystems.com/