Hi.
Had a litle rattle sound under the front of the valve cover of my -93 520IA so I lifted the cover and all seems OK, just moved the DOHC chain tensioner a bit up and down. And the sound seems to be gone. Knock knock.
Saw a unit I never seen in a car before the "AT adjustment unit" in front of the intake side camshaft. Whats that? "Adjustabe Timing"? of intake valves.
/Tibbe
Found on the internet: http://www.bmwworld.com/technology/vanos.htm
It's the VANOS unit variable input camshaft timing on the M50 engines.
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VANOS operates on the intake camshaft in accordance with engine speed and accelerator pedal position. At the lower end of the engine-speed scale, the intake valves are opened later ( 12.5 degrees ) , which improves idling quality and smoothness. At moderate engine speeds, the intake valves open much earlier, which boosts torque and permits exhaust gas re-circulation inside the combustion chambers, reducing fuel consumption and exhaust emissions. Finally, at high engine speeds, intake valve opening is once again delayed, so that full power can be developed.
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More info: http://www.ukcar.com/features/tech/Engine/vv/vvt_3.htm
It has variable timing, does it have a PWM or on/off control valve?.
Last edited by tibbe; 11-12-2005 at 05:54 PM.