Video explaining vanos operation for anyone interested

BMW VVT Vanos CAM Timing - YouTube

How VANOS works - YouTube

Thanks amacman.

This is what I found in bimmerforums:

Vanos Solenoid done... WOW, what a difference - Page 8 - Bimmerforums - The Ultimate BMW Forum


All this being said, most ppl i read on here run heavier weight oil. However being that I have no problems running what I run I dont want to change just for the hell of it.
(other than that occasional bump in idle, i have a 95 m3, and it only occurs if i put it into nuetral and coast to a stop... i am reading NGK spark plugs for 96+ m3 will help with this?? my bad off topic)

Many people do not realize this but vanos is COMPLETELY run on oil pressure alone. If you do not have the proper oil pressure you have no vanos. Imagine the vanos system as a dual oil path way maze. one oil pathway is for when vanos is not engauged, the 2nd is when the vanos is supposed to be engauged. the thing that shifts between the oil passages IS the vanos solenoid, thatts why it is such an essential part of vanos. without it you have no vanos. if the solenoid does not operate 100% vanos will not work properly. Lets say the vanos only has enough force to push change the machanism that changes the oil pathway 50%, well that means only 50% of oil will get into the "vanos on" pathway and thereby reducing pressure greatly which will then in turn only move change the cam timing by 6 degrees (instead of the full 12 as it is supposed to in the mid range).

Another factor that is essential is the oil ITSELF. it is the mechanism by which u push the vanos gears. If you use a really thin oil (aka mobile 1), it flows like water and it does not have the same oil pressure as a much heavier 15w-50 weight oil which is much thicker (think of molasis). the 15w-50 is able to "push" the vanos to the proper specs better b/c it has higher compression & oil pressure characteristics and is much thicker. so your oil is just a crucial aspect as the solenoid or vanos mechanism itself. Thats why you see so many people say "i replaced my vanos but the noise came back!" well duh! u are using the wrong oil or your solenoid is bad.

So basically... if you are have vanos problems here is the order you should replace things...

1) change to a much thicker oil (preferably a 5w40-20w-50, bmw recommends 20w-50 for a reason, but you can do castrol 5w-50 which will work in pretty much every weather condition & bmw recommend castrol anyways).

2) change vanos solenoid

3) then replace vanos unit if necessary (though I have spoken to NUMEROUS BMW master techs and every single one dispelled the "vanos stuck" myth. it simply cannot happen they say, jus thought i'd share that).

hope this info helps you guys out.

Last time I check BMW didn't recommend 20w50

You have the vehicle home home right?
I would redo the leak down test, did the shop do a leak down?
If its still coming out the oil cap, its not the vanos.


To everyone else, its not an electrical issue, he has low compression.
Grounding every single coil, nut, and bolt will not help bring back his compression.
Good effort though.

I will be dropping it off at a different Indy shop this morning on my way to work.

Would it of been possible for the other Indy shop to accurately diagnos the vanos as the culprit without digging into the engine?

From what I can tell, the only thing they did other than the diagnostic was unplug some sensors and solenoids.

By "the diagnostic" do you mean pulling the codes?
Diagnosis is performed by spending time to find the route cause of the fault.
I have no idea what they did or even if vanos failure could cause misfires/low compression. But my gut says no.

Are these BMW specialists you are taking it to, or do they service all makes?

They pulled the codes and did some addl checking......don't know what the "addl checking" entailed.

The second Indy shop confirmed their findings.

I have zero plans to put $1800 into this car but I do have the desire to try and do the vanos work myself.

My debate right now is deciding which would be easier, to install a new driver side vanos or get a used head assy with the vanos already attached. I can get a driver side head with a fully functional vanos, cams, lifters and valves for $250.

I just don't know which would be the less difficult to deal with.


Any ideas?

Whoa , Stop , Hold yer horses .
If you have low compression then you have other problems , not the vanos .
I have not read 13 pages word for word but you need to be absolutely sure what requires repair .
Low compression means cylinder head removal to repair the fault .

Did you tell the second shop about the findings of the first? Might have biased their findings?

I ask because your leakdown test revealed leakage past the pistons/rings not the valves like it would have if I really was a vanos problem.

I don't recall if it came up or not. I wouldn't think I would of told them but sometimes things slip out.

Now here's something interesting......at least to me it's interesting.

When I first purchased the car it was giving only the #6 misfire code, so after changing the water pump, I pulled the codes again and still was getting only the #6 misfire code.

So I replaced the #6 ignition coil but the misfire didn't go away and eventually I started getting the multiple misfire code (p0300) and the other 4 misfire codes for cylinders 5,6,7 and 8.

After changing the plugs, switch the ignition coils from one side to the other.....I still pulled the mutiple misfire codes for all cylinders on driver side.

Then I changed the valve cover gaskets, the intake manifold gaskets and the throttle body gasket and after that I only pulled the #6 misfire code. But a few days later the other misfire codes came back.

Now i changed the oil and today I checked the codes and the only one I pulled was the #6 misfire code.

I did disconnect the battery earlier, so it may just take a while for the other codes to generate.

But I do find it odd that the #6 misfire is always constant but the others are not. Seems strange that #6 always throws a code days before the others.

If the vanos is stuck in an open position, causing for the cam shaft to be turn x degrees all the time, that would mean all of the cylinders are equally off in their timing. So that would also mean they should all throw the same codes at the same time.

Your thoughts....