Timing chain loose?

[DanQ]

Hi All,

I have a 1993 525 (Vanos) that has been backfiring on startup and I'm trying to hunt down the problem. You probably saw some discussion on the subject here: http://www.bimmernut.com/forum/showthread.php?t=42567

I pulled the valve cover off to check the timing and make sure things are lined up as far as valve timing. While turning the engine manually, I found that the exhaust cam starts to move before the intake moves. I would expect both to start moving simultaneously. Has anyone seen this behaviour and is it normal?
It makes sense to me that if the intake cam is engaged late due to a loose chain, the intake timing is essentially retarded and would keep the intake valve open upon ignition of cylinder.

Thanks for any input on this.

[Blitzkrieg Bob]

Hope you are rotating the crank clock wise....

Keep in mind that the first few tugs on the crank without the Vanos being pressurized can leave some sloppyness as the un pressurized vanos is rotated and the intake gear is allowed to move a few degrees as the play is taken up.

[Bill R.]

Agree with Bob, vanos allows some play in the gear, normal.