Vanos

[R&D man]

I have my m50 swap complete and have neen driving for a month now.I have been wondering how to check the operation of the vanos unit in the car.The engine sat in a dry environment for 2.5 years and I have a concern for the o rings in the vanous.

Thanks

[jrdeamicis]

There is O-ring kits you can buy for your vanos. Besian Seals?

[R&D man]

how do know if it is working

How do I know if the unit is working properly/

[JGood]

There's a few things that can fail. The solenoid can fail, so it won't actuate the vanos unit itself, or the vanos seals can fail, so the oil will flow past the piston seal instead of pushing the piston.


Solenoid test, from the Dr. Vanos website:

----------------------------
"(US Single Vanos Solenoids only) It's very rare that a vanos solenoid needs to be replaced. Typically the wire lead becomes damaged and breaks or shorts out, but the solenoids are otherwise very durable.How to test your solenoid: Unplug the wire lead at the back of the solenoid from the main wiring harness first. Remove the solenoid from the vanos unit with a 32mm wrench, and jump the connector to a 12v power source and ground. Note that there is a + and - marking on the connector. Be SURE to connect the leads properly or you may damage the solenoid. The pin inside the solenoid should 'pop' out approximately 5mm. If not, the solenoid needs to be replaced."
----------------------------




I don't know of a way to test the vanos unit seal.

[Voluted]

You can test the vanos unit with this tool and an air compressor:

http://cgi.ebay.com/ebaymotors/BMW-VANOS-Compressed-Air-Fitting-Adapter-El-Paso-Tool-_W0QQcmdZViewItemQQhashZitem19bcc9921cQQitemZ110541509148QQptZMotorsQ5fAutomotiveQ5fTools

Looks like this:

http://www.youtube.com/watch?v=2q4x3hgnsNM

While holding pressure in the vanos unit, keep an eye on the camshaft. If it starts reseting back to it's original position than there is a leak in the vanos seals.

[markseven]

How do I know if the unit is working properly/

Dyno? You should see the curve shift upward at 4K (I don't know if VANOS kicks in at 4K on the non S motors). On the S52 you can feel in the increase in power at 4K.

[JGood]

Dyno? You should see the curve shift upward at 4K (I don't know if VANOS kicks in at 4K on the non S motors). On the S52 you can feel in the increase in power at 4K.

Vanos kicks in just off idle 6 degrees, then again just after 5k another 6 degrees. There's isn't much of a dip or change at it's switchover point. If you have a noticeable step in power at 4k, you may have a problem.

















etc....

[matt]

Vanos kicks in just off idle 6 degrees, then again just after 5k another 6 degrees. There's isn't much of a dip or change at it's switchover point. If you have a noticeable step in power at 4k, you may have a problem.

Err... close.

Vanos engages (advancing the intake cam 6-12 degrees) just off idle. It then disengages at 5000-5500RPM.

When you see a dip in a dyno graph between 5000 and 5500, that means that vanos is disengaging properly, but the cam timing does not match the tune on the motor, so the crossover point of the ECU maps doesn't match the crossover point of the airflow of the motor.

Matt

[SwiftE30]

This might be a very dumb question to those who are knowledgable on this subject, but what exactly is VANOS? I know it a timing thing, but what exactly does it do?

[FredK]

Depending on engine speed, it is a electrohydaulic system that can advance cam timing to change the volumetric efficiency of the engine.

You've heard of slotted cam gears, so that you can advance / retard timing on something like an M20, right? Well, VANOS does something similar, except you're not limited to a single fixed position when you bolt the valve cover back on. Instead, it couples the intake cam gear to a helical gear, which is driven by an electrohydraulic system, to control advance/retard.

[JGood]

Err... close.

Vanos engages (advancing the intake cam 6-12 degrees) just off idle. It then disengages at 5000-5500RPM.

When you see a dip in a dyno graph between 5000 and 5500, that means that vanos is disengaging properly, but the cam timing does not match the tune on the motor, so the crossover point of the ECU maps doesn't match the crossover point of the airflow of the motor.

Matt

Oh, interesting. Thanks for the correction. So how does it decide how much advance to give it? Is it variable between 6-12 degrees, dependent and RPM and load, between ~1000 - ~5000?

While were on the subject, my m50 with s50 cams and tune, is a little jerky around 4-4.5k. If I gradually lay into full thorttle at 4K, by the time I get to 4.5K, it will have surged once or twice. It's only in that RPM range, and only when increasing throttle load. If I'm full throttle from 3k, it won't do it at all. The vanos has a Beisan seal kit but makes some horrible noises. I'm replacing both tensioners, the vanos unit, and the solenoid tomorrow, and am using another Beisan seal kit on the new vanos. If this doesn't fix the surge, any ideas what that could be?

[matt]

It's not variable at all, the 6-12 depends on how you install the vanos when you assemble the motor. If you have it set for 10deg, you get 10deg every time.

Hm, it could be a lot of things. You may be operating right at the line between vanos on and off (this is based on engine load) so it may be oscillating. Or it could be any number of other things.