Vanos Innerworkings

[Beej '86 325es]

I have apart a dual vanos unit, trying to figure out how it works exactly and if it is missing any parts. What confuses me is that the intake side has a spring in it, but the exhaust doesn't. Maybe someone here that better understands the M52TU / M54 engine could explain to me if it is missing parts or not. When assembled, the side without the spring feels more like the the single vanos units I have, in that it actually moves.

Any takers?

[m42technic]

I dont usually have VANOS units apart, theyre usually replaced as units here at the dealership. Do you have access to the ETK?

[Beej '86 325es]

Yes, and I've looked at all types of vehicles with dual vanos, and they all just show the unit alone. The furthest they show them broken down is like taking out the solenoid.

[trent]

BJ,

Dual vanos is a pretty awesome mechanical achievement. We had to buy $400-500 worth of special tools to remove/reinstall dual vanos cars. Just last week we put a set of Schricks in a 328 and man....watching the tech its fucking ballsy lookin -- one wrong move and ALL THE VALVES ARE BENT on restart :)

[m42technic]

Yeah, timing the cams with dual VANOS can be a PITA. First time I did it, took 3 trys to get the timing right. :P

[Beej '86 325es]

Bizzump.

Ok, let me ask this...
On the dual vanos unit, can you pull one side in and out fairly freely and the other you have to push hard because of the spring behind it? :?