Vanos break in?

**BMWMK2** · 01-13-2015, 12:21 PM

Just replaced the vanos unit, spark plugs and crank seal. Is there a definite break in period for the vanos, and if there is will the results change as it breaks in?

**rf900rkw** · 01-13-2015, 12:49 PM

What would need breaking in?

**BMWMK2** · 01-13-2015, 01:27 PM

I have read that some people say to drive lightly when replacing the vanos seals for a period of time. I don't know why or if that is necessary.

**rf900rkw** · 01-13-2015, 01:36 PM

You can read just about anything you want to on the webz. It makes zero sense. It's just a teflon seal. There's nothing to break in. You certainly don't want the teflon wearing in a few hundred miles.

**BenFenner** · 01-13-2015, 02:12 PM

Agreed, nothing to break in if you've rebuilt your own VANOS unit.
If you've bought new (or new to your engine), then technically there could be a small amount of break-in for the helical gear that interfaces with the cam sprocket. For on/off VANOS systems like the S52, these components slide back-and-forth between each other when VANOS activates which really you have little control over and thus makes no sense to try to drive differently. Yours being an M54 engine (I think?) has dual variable VANOS (I think?) which does give you some control over how fast it activates. You can severely generalize it, and assume it will move with RPM. However, with how little actual break-in there could possibly be between these two components and how smoothly the variable VANOS system works I wouldn't treat the car any differently. In essence, for various reasons, there should be no different behavior from the driver during break-in regardless of VANOS type. Just drive as you would normally. If that means thrashing it, then go ahead.

**HeliHover** · 01-13-2015, 02:41 PM

Beisan recomends a 200 mile (think it's 200) "break in period" with the seals they sell. They recomend regular driving with out spirited driving. As said above your not breaking anything in, your making sure the new seals seat properly.

**rf900rkw** · 01-13-2015, 02:49 PM

If you barely touch the throttle, at 2xxxx RPM the solenoid fires, the oil flow reverses, and the piston moves as fast as the oil will push it to the other side.

If you MAT it, WFO baby, at 2xxxx RPM the solenoid fires, the oil flow reverses, and the piston moves as fast as the oil will push it to the other side.

The dual vanos timing is a tad bit more complicated, but the same thing applies. Engine torque output has no bearing on the VANOS seal loads. Cam and vanos loads will be the same per given RPM no matter the VE.