Vanos "frame" flexing when actuated

[MatRacer]

After reinstalling the cams on my S52 and doing the timing, I checked the actuation of the vanos with air. My regulator was set at 60psi. The vanos was doing its job, but the vanos structure or frame or call it as you wish is flexing enough for me to notice it when actuating the vanos solenoid! Is this normal?

[Nutzy]

Mine does that. No idea if it's normal.

[MatRacer]

Its like if the big spring washer was too tight or if the cam was too hard to turn...I assembled the cams in engine assembly lube... maybee its kind of sticky,,,

but the system must have been designed to handle the 60psi of oil pressure!

[328ijunkie]

You have to keep in mind it has an easier time when the motor is spinning

[MatRacer]

Mine does that. No idea if it's normal.

Did you ran your engine like this? if yes for how long?

[fiveightandten]

Mine doesn't do that. I'm not sure exactly where you can see it flex, but here's a video of mine. You can't see the whole VANOS unit, but it's better than nothing. This is with cam blocks installed.

https://www.youtube.com/watch?v=0GUHUkiDe9Q

[MatRacer]

In that video, the exhaust cam gear bolts must be loose. The vanos unit is getting it easy since it doesn't have to rotate the cam... it only rotates a loose cam gear. I took a video of mine, but we are not really seeing it flex in the video... pretty hard to catch.

[MatRacer]

Anyway here is the video

After looking back to it I think we can see it at like 0:09 - 0:11...

https://vimeo.com/164326688

[fiveightandten]

In that video, the exhaust cam gear bolts must be loose. The vanos unit is getting it easy since it doesn't have to rotate the cam... it only rotates a loose cam gear. I took a video of mine, but we are not really seeing it flex in the video... pretty hard to catch.

Everything was tight in that video, but the cam blocks are on, so it wasn't rotating the cam gear. That was in 2010, and I haven't had the valve cover off my S52 since, so I can't quite remember how the mechanism works and what else was rotating instead. It may or may not be under less load than rotating the cam.

Anyway here is the video

After looking back to it I think we can see it at like 0:09 - 0:11...

https://vimeo.com/164326688

Yeah, I can see it towards the end of the video. Weird. Have you rotated the engine by hand to make sure everything is smooth? If it's all timed right and smooth, i'm not sure i'd worry about it much. While it's rotating and lubricated, I would think it will see less resistance than when actuating from rest in a cold somewhat dry engine.

I looked around at some more VANOS videos, but I can't see if it's doing the same on other people's engines. I'd check mine again, but I don't have the tool anymore.

[MatRacer]

Yeah, rotated the crank like 5-6 complete turns... everything was alright. As you can see the vanos operates just fine except for the bending... I guest it's OK and it will ease when fully lubed and in motion, as you and 325i junkie said...

[fiveightandten]

Yeah, rotated the crank like 5-6 complete turns... everything was alright. As you can see the vanos operates just fine except for the bending... I guest it's OK and it will ease when fully lubed and in motion, as you and 325i junkie said...

Agreed. FYI, there is an OBDII code for "VANOS mechanically stuck". I can't remember exactly what situation throws the code (cam position sensor data? ). But, the point is, if it was seeing an undue amount of resistance, you might actually get a code from it.

A friend of mine rotated the cam gear on his too much when installing the VANOS, and consequently it wasn't actuating fully. It threw a "VANOS mechanically stuck" code immediately when he took the car out.

I'm not sure if that eases your mind a bit or not.

[MatRacer]

Will run the s52 with OBD1 management..don't know if it can also detect it... but anyway, after thinking more about it pretty sure it's gonna be just fine

Thanks man!

[Northern]

there is an OBDII code for "VANOS mechanically stuck". I can't remember exactly what situation throws the code (cam position sensor data? ).

Yes. One of the failure modes for a bad cam sensor is this code as well. If the wires rot out, and the sensor is just feeding a garbage signal to the ECU, it doesn't see the cam advance when vanos switches on.

[328ijunkie]

https://www.youtube.com/watch?v=4_LaDBaF1iQ