MYM05

So far I know there are electrical and mechanical components of Vanos.
Electrical failure --> computer code will flash, SES light
Mechanical failure --> loss of power, bumpy idling / revving.

What is the worst case scenario that can happen when there is faulty Vanos. Will it cause bent engine valve? If so, how?

What is the protocol for BMW US to decide when to replace the Vanos? In Australia here, I was told that they can just recommend to replace the Vanos if it is noisy, because noisy Vanos means that there is no enough oil pressure in the unit.

Thanks

Nelson

radartrap

Last year the Vanos failed on my 2000 E39. Symptoms were rough idle, "pushrod V8" exhaust sounds, smoky exhaust. My code reader told me it was an O2 sensor. Then the car developed an alarming oil leak out of the left front spoiler. Turned out the Vanos pump was leaking. It allowed engine oil to be sucked throughout the intake system, necessitating the dealer to remove and clean it, at major expense. Did a nice job, but it was costly.
I've seen earlier posts on this board re. when the dealer will or won't replace Vanos.

DouglasABaker

Worst case scenario of failed VANOS is a really big bill to replace it. In and of itself, the VANOS cannot cause engine damage through failure. Related failures, such as a broken timing chain or one that jumps a tooth are clearly a different issue and can cause significant engine damage.

Honestly, having read a fair bit on VANOS and being reasonably familiar with variable valve timing in general, I can't see how the mechanicals of a VANOS could failure. The monitoring components are certainly suspect (CPS) and the solenoid itself can go, but even in these cases, the expensive part of the system (the mechanicals that actually change the timing) are unaffected.

d-

ard

Isn't there a history here?

You are asking a question without an answer.

In the US, they replace the VANOS when the GT1 indicates a bad Vanos. A dealer can recommend anything they damn well please... this is especially true when WHO is paying can be a subject of disagreement.

Is yours noisy, is the valve bent, is there a few pages of 'story' behind this?

I won't post the links to your long stories of woe, but rather ask that you do the members here the courtesy of posing a question in context. Bring up the old threads, with all the background, and ask for help with the next step.....

Geez...

andy777

I had a faulty solenoid a while back and it took me about 3 weeks to get the problem fixed, as far as the engine being damaged I agree with Doug.
In my case the car would work almost normally until the soleniod needed resetting (turning the car off and on). If I was unable to do this i.e. no where to pull over it would run rough and misfire.

MYM05

Hi ARD,
I just didn't want to bore everyone here with my long story. But here it is
Back in June, I need to have my timing chain components all replaced because I have a broken timing chain guide. There are metal filings in the oil system from timing chain rubbing the guide, dealer told me to replace the engine at my cost. I said no because the car had good compression, doesn't have a rough engine idling, and no computer code had came out. After the timing chain replacement (we waited 2.5 months for parts), the engine stalled. According to the dealer, the engine did ran for 30 mins before stall.
The following report was written by Hans, the inspector who work for the local motor association. Motorline BMW didn't want to write a report, but they assisted Hans.


I have read the comments made by the other M5 owner and have thought about it and I feel that he is correct on some points.

(1) The Engine Control Unit (ECU), camshaft sensors and Vanos control valves control the position (angle of advance or retard) of the camshaft in relation to the timed timing chain sprocket. The timing chain sprocket, crankshaft and camshafts will all be synchronised and remain so if the basic setup had been followed. (Please disregard the fitment the Vanos system here for the moment) I believe that Motorline has set up these components correctly otherwise the engine would not have run following the completion of the timing chain replacement and the engine would have been damaged when the engine was first turned over.

(2) We have been advised that the Vanos system has to be set to a default position before fitment to the engine. This procedure involves applying compressed air to an oil hole in the Vanos unit and that this should position both the camshaft position actuators in their default position. The Vanos unit is then inserted into the camshafts and secured. If the Vanos system is functioning normally the engine will run as designed. Assuming that the the Vanos unit is in the default position, if for any reason the camshaft sensor or Vanos control valves malfunction, then the worst case scenario would be that the engine would run rough. (ie. its operating parameters have not been breached.)

(3) In the case with your vehicle, we believe that the Vanos exhaust camshaft position actuator was not in the default position and was in effect stuck in an advanced position. This would have allowed the engine to be started and the engine would have been running well whilst the exhaust camshaft position actuator was stuck in the advanced position. However, if the exhaust camshaft position actuator suddenly managed to free itself due to the action of oil pressure, heat (as the engine warmed up) and some normal engine harmonics together with the control components directing the camshaft actuator to move to the retarded position (as would be the case above idle speed), then this retardation could result in a greater exhaust valve overlap and corresponding higher exhaust valve lift than normal near Top Dead Centre. This greater than normal exhaust valve lift near Top Dead Centre in turn would be in conflict with the engine cylinder's pistons and they could touch resulting in bent valves.

(4) We have been advised by the repairer that there are no checks that can be made on the Vanos unit itself to ascertain the position of the exhaust camshaft position actuator. It would also be timely to mention the oil and metallic swarf as other contributing factors to the Vanos malfunction. The Vanos unit is normally replaced as a complete assembly.

I doubted the engine ran for 30mins, but have no proof.

Another point is that I did asked consultant in Motorline back in Aug 08 (this is while I am waiting for the timing chain parts to arrive) about replacing my Vanos together with timing chain (because I can save on labour cost), to my surprise, they said no. And now they blame on the Vanos was faulty and caused all these bent valve.

I also have enough evidence to show that my Vanos was working except it was making some noise. Just before the timing replacement, I had compression test done and were all good, not idling rough, and no code ever came out from the computer. So it is only setup error that can cause these valves to be bent.

The reason I opened this thread is that once I am sure that the Vanos failure alone will not cause bent valve, I am taking legal action against the dealer. Dealer is towing my car back to me tomorrow. We already spent 4 weeks trying to sort this issue out. Now they don't want to touch it anymore.

Nelson

ard

This may be the crux of the issue.

The BMW dealer that trashed your motor told the inspector "the position of the vanos cannot be ascertained prior to insertion".... they are therefore claiming the vanos was 'bad', they installed it, and it damaged the motor when it 'realigned'.

Had you posted this in your other threads, all the knowledgeable people who had posted in there might have received an update (perhaps an email notice) and could have replied.... In reading on VANOS (and on Phillym5's comments) you can, actually, check the valves and vanos psotions when you set the timing.

Hans doesn't understand how vanos work- nor does your dealer- and the dealer has led Hans down the path they want.

I suspect they are lying about 30 minutes of running. I wonder of there were any DME tests that would show operating hours prior to, and just after, the 'event'.

My 2 cents.

You will now get a rash of people's opinions on their VANOS problems, but might not get the attention of the folks that had weighed in on the other threads...

ard

PS I think the VANOS psotion CAN be checked, I think the position of the actuators CAN be checked, and I'd try to find the actual BMW repair procedure in which they MAY provide explicit instructions about this...

DouglasABaker

The position of the VANOS is checked using a pair of electrical terminals on the front. This is how you check to ensure the VANOS is fully retarded.

Doug