Failed vanos test

[M3kob]

what's so special of having a broken tab vs 2 broken tabs? Vanos should continue to work with one broken tab as it still drives the pump disk.

OP, you might want to check the pump pressure.

how can the pump pressure be checked?

[BMWfanz]

U need special gauge and modified banjo bolt on pressure line

[oceansize]

I bought this:

https://www.amazon.com/Winters-Stainless-Pressure-Internals-Accuracy/dp/B0087UYHGS

[M3kob]

U need special gauge and modified banjo bolt on pressure line

thank you.

I think I’ve found correct fitting and gauge and placed order.

even though i’ll be rebuilding vanos, it will be interesting to see oil pressure.

[M3kob]

Parts came today and this is the pressure which looks good, so I’m baffled. This is on idle

[maupineda]

That’s good, make sure it holds when the oil is hot, ideally at 90-100C

[M3kob]

That’s good, make sure it holds when the oil is hot, ideally at 90-100C

thanks. Will need to wait until Friday evening when I have some more time.

if the pressure is correct, what could be causing the vanos test failure?

[maupineda]

Vanos test will not start until oil temp is >75C.

when I had a bad Vanos, when cold it would be 115bar but dropped to 40bar when hot.

did you let the oil to fully warm up?

[Slideways]

Vanos test will not start until oil temp is >75C.

when I had a bad Vanos, when cold it would be 115bar but dropped to 40bar when hot.

did you let the oil to fully warm up?

I believe coolant temp has to be >75C and oil temp >40C. Other two conditions are no faults stored and engine at idle.

[M3kob]

Vanos test will not start until oil temp is >75C.

when I had a bad Vanos, when cold it would be 115bar but dropped to 40bar when hot.

did you let the oil to fully warm up?

I didn’t today when checking pressure, prior to that I did as the procedure won’t start before coolant above 75degC and oil above 40degC. Didn’t have enough time today with the car to get it up to temp, will try tomorrow/Friday and check pressure on gauge

[M3kob]

I believe coolant temp has to be >75C and oil temp >40C. Other two conditions are no faults stored and engine at idle.

Yes that’s what procedure showed. I have no fault codes but it seems to hunt on cold idle.

[sapote]

if the pressure is correct, what could be causing the vanos test failure?

* cam timing was wrong. need to double check the timing setting with VC off.
* vanos solenoid pack or its wirings.
* cam sensor signals

[M3kob]

* cam timing was wrong. need to double check the timing setting with VC off.
* vanos solenoid pack or its wirings.
* cam sensor signals

UPDATE

Managed to warm it up today and monitor pressure as oil got hotter. Pressure drops as oil temp gets warmer:

cold : 1500psi
49degC : 1100
63degC : 1000
71degC : 1000
80degC : 900
90degC : 900

[sapote]

UPDATE

Managed to warm it up today and monitor pressure as oil got hotter. Pressure drops as oil temp gets warmer:

cold : 1500psi
49degC : 1100
63degC : 1000
71degC : 1000
80degC : 900
90degC : 900

900 psi is too low. Was anyone working on the vanos and the pump disk recently?

[M3kob]

900 psi is too low. Was anyone working on the vanos and the pump disk recently?

not as far as I know.

I purchased car in September 2025 and barely done any miles since then. Been stalling interior, quarter as seals etc. Vanos looks original. As mentioned I’ve got a recharged accumulator so will try and fit that tomorrow and see if it helps but I’m guessing it’s going to be vanos rebuild