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Thread: Single VANOS install important consideration that no one talks about.

  1. #1
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    Single VANOS install important consideration that no one talks about.

    I want to share my experience and thoughts about single VANOS installation procedure, which is so well documented on the internet, and yet, there is an important piece of information/step that is never discussed or even thought of. And if it has, please send me the source, I really need a confirmation on this. All experienced installers are welcome to join and I would really appreciate your thoughts.

    So the step is described here in BMW TIS as follows:

    VANOS.png

    Second picture has an important step: Before fitting adjusting unit (VANOS), push back splined shaft with hydraulic piston (1) in direction of housing (2) up to limit position.

    In my opinion, this step is misleading and has no effect on timing whatsoever. Important part is the first tooth engagement as you rotate the sprockets counter clock wise, but it doesn't matter if the piston is fully pushed in or extended - you can collapse it later.

    The IMPORTANT piece, however, that is never mentioned (and I am sure has been the cause of plenty wrong installs, although the instructions have been followed to the tee) is that the above splined shaft must be in a fully pushed in/collapsed position RIGHT BEFORE you tighten the four exhaust sprocket bolts. NOW THIS IS IMPORTANT, but never mentioned anywhere.

    Just think about it, let's say you follow the instructions and you push in the shaft, then you engage the first tooth successfully as you rotate the sprockets counter clock wise with the sprocket tool. Nice job! You keep rotating the sprockets CCW until the VANOS is flush with the head. And this is where you can screw up: nothing will stop you from continuing to rotate the sprocket counter clock wise. If you continue, you will start extending the shaft from its collapsed position, until it bottoms out.

    The bottom line here is that you can rotate the sprockets back and forth not only to "mount/dismount thee VANOS", but also to extend collapse the VANOS shaft after it is installed and bolded on.

    How many DIY-ers wondered at which shaft position should they secure the timing between the cams and start tightening the four bolts on the exhaust sprocket? Should the sprocket be fully collapsed or fully extended or somewhere in the middle?

    BMW TIS clearly states to collapse the shaft before the install. Fair enough. But how many DIY-ers double-checked that they didn't rotate the sprockets counter clock wise just a little bit too far, effectively extending the shaft by 1-2 mm and screwing up the VANOS range in relation to TDC of the exhaust cam?

    Please join the conversation and share your thoughts!

  2. #2
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    It doesn't matter is why. If it does say collapse the shaft then its relatively useless as the shaft length doesnt effect the rotation of the gear until after assembly and the gear is properly in the camshaft

    As long as you engage the gear at the right spot when drawing it into the intake camshaft the timing is correct. Your supposed to draw it in all the way until the hellical gear bottom sount on the inside camshaft gear so there isnt any way to "over" draw it in. The camshafts are supposed to stay at tdc timing the entire time. The camshafts arent supposed to ever move in the process of sucking the gear in.
    Even if indeed that isnt the "start or idle" cam position, the car uses the cam sensor, the vanos system to make aure it corrects. The entire vanos system moves and controles the shaft length and thus the cam timing through the hellical gear. It makes no difference after startup even if the gear isnt fully inserted, as the system would naturally pull it in itself just as it would during vanos activation or deactivation. It only matters that the vanos works, and the gear is installed properly.
    Nobody would recertify these machines after somebody screwed with them without any visibility into what they did.

    HONK! HONK! Clown car coming through!

    -Oakdizzle

  3. #3
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    Quote Originally Posted by spyderg0d View Post
    Your supposed to draw it in all the way until the hellical gear bottom sount on the inside camshaft gear so there isnt any way to "over" draw it in.
    This is wrong. This is exactly why I think this conversation should happen. If you draw the helical gear until it bottoms out on the intake cam, then yes, there won't be a way to rotate CCW any further, but you have effectively killed your VANOS range and disabled it's function.

    During assembly, right before you tighten the exhaust sprocket bolts, and your cams are at TDC:
    1. If the VANOS piston is fully extended, then available piston travel is extended > compressed. After all is assembled, the extended piston will bring cams to TDC and compressed piston will retard the intake counterclockwise.
    2. If the VANOS piston is fully compressed, then available piston travel is compressed > extended. After all is assembled the compressed piston will bring cams to TDC and extended piston will advance the intake clockwise.
    3. If the VANOS piston is somewhere in between, then available piston travel is both directions. After all is assembled the compressed piston will retard the intake counterclockwise past TDC and extended piston will advance the intake clockwise past TDC.

    VANOS is designed to advance the intake starting clockwise from TDC, and not retard in any way. This is OPTION 2 above.

    Option 1 will have the piston already fully extended at TDC, therefore leaving it zero travel towards advancing further
    Option 2 is correct - there's 100% travel available
    Option 3 gives some room for advancement, but not 100%, limiting the full potential of the VANOS advancement.

    You are correct that the system will auto-regulate due to sensors, and it'll probably never push the VANOS towards retarding the intake. But the issue is that you physically limit the advancement potential in option 1 and giving it a bit of advancement potential in option 3, which completely cancels/reduces the intended functionality of VANOS.
    Last edited by make it easy; 06-16-2019 at 01:44 PM.

  4. #4
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    Another obesrvation.

    I cannot understand the so-called "mistake" of not engaging the splined shaft with the very first tooth. The common explanation is that you are reducing the "travel" of VANOS and therefore the advancement. In reality, it's the options 1 and 3 described above that are limiting the advancement. The story with the "first tooth", however, is misleading as well.

    As you guys remember, when you install the sprockets, you must ensure that both sprockets can move from one end of the elongated slot to the other end. And supposedly, if you don't engage the very first tooth during VANOS install, then you will not be able use all that travel range.

    In reality, you will find that the real sprocket travel range after the VANOS is attached and bolted on is about 30% of the entire sprocket travel, when VANOS was out. These 30% fall in the middle zone of the elongated slots on the sprockets. Why so? Because the VANOS piston travel is much shorter, and the elongated slots were made longer, to account for potential errors, like when you don't engage the splined shaft at first available tooth. Ok, so you've skipped 2 teeth, these 30% of real VANOS travel have shifted a bit to the right of the elongated sprockets. So what?

  5. #5
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    Your not correct in saying its ok to have the piston in any position. The piston HAS TO BE all the way retracted. The gear on the piston locks the two gears together at a certain position. If you sloppily push the gear on the vanos on to the engine and then with a wrench rotate the cam sprocket and push the vanos on to the engine then while your pushing you are still compressing the vanos piston and may screw up locking the two gears together. The only way to fully ensure the two gears are locked together is when your pushing the vanos onto the engine and locking them together, the piston has to be fully retracted to achieve this.

    The only problem I have with the Beisan guide is where they show people to use an xacto knife to cut the old o-ring out. Stupid people stab into the vanos as did the retard that previously owned/worked on my car.
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  6. #6
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    Quote Originally Posted by Eric93se View Post
    Your not correct in saying its ok to have the piston in any position. The piston HAS TO BE all the way retracted. The gear on the piston locks the two gears together at a certain position. If you sloppily push the gear on the vanos on to the engine and then with a wrench rotate the cam sprocket and push the vanos on to the engine then while your pushing you are still compressing the vanos piston and may screw up locking the two gears together. The only way to fully ensure the two gears are locked together is when your pushing the vanos onto the engine and locking them together, the piston has to be fully retracted to achieve this.

    The only problem I have with the Beisan guide is where they show people to use an xacto knife to cut the old o-ring out. Stupid people stab into the vanos as did the retard that previously owned/worked on my car.

    I don't know why so many DIY guides are telling to PUSH the VANOS onto the engine in order to engage the gears. This has never been a part of the official procedure. You turn the VANOS shaft with your fingers until its internal teeth engage with the teeth on the cam, then you observe the first available tooth on the sprocket and turn the chain CCW with your hands until it aligns with the outer teeth on the VANOS shaft (maybe 0.5 mm turn). Then you slightly slide the shaft into the teeth on the sprocket for the very initial engagement and done, you don't need to push the VANOS - it gets sucked in by itself as you rotate the sprocket CCW with the tool. BTW, if the piston is extended, you get much better clearance to play with the shaft.
    Last edited by make it easy; 06-17-2019 at 02:10 AM.

  7. #7
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    Pushing it on aids the process. It's important that the vanos piston is fully retracted, the intake sprockets get locked together. The process is simple why try to take away from it. People still mess it up.

    If the piston were extended the vanos body would be off the engine . With the piston fully retracted the vanos body just starts to engage the studs.
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  8. #8
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    Quote Originally Posted by Eric93se View Post
    If the piston were extended the vanos body would be off the engine . With the piston fully retracted the vanos body just starts to engage the studs.
    You just push the Vanos onto the engine after the "teeth locking" part is done. Nothing will change in the end, same result.

    Look, some people might prefer to fully retract the piston and push on Vanos during teeth engagement, effectively sliding the VANOS towards the engine. Although it's not very accurate and might take a few attempts to hopefully "feel" that first tooth, that's fine, their choice.
    Others, however, will follow the official BMW procedure and use their fingers to slide the splined shaft onto cam teeth first, and then manipulate the shaft and sprocket (with fingers) to match outer teeth with the first available tooth on the sprocket. Having the shaft fully extended gives you much better access and you can actually see that very first tooth that you need to engage with (instead of trying to feel it when you push the VANOS). Although it takes a few more words to explain it, this is by far more accurate and easier to perform with a 100% result from first try.

    Everyone picks their poison, however they see fit. Above is not important, that's not my point. What I am trying to say, is that the retracted piston matters NOT during the teeth engagement/VANOS mounting procedure, but AFTERWARDS, when VANOS is bolted on, but BEFORE you tighten exhaust sprocket bolts.

    DIY'ers think OK, I got the piston retracted before I even start sliding VANOS onto studs, then I'm good throughout the rest of the timing procedure. WRONG! It is so easy to screw it up! You push the VANOS towards the engine while rotating the tool CCW, and soon the VANOS is flush. If you are not careful and kept on rotating the tool CCW just by a few degrees, VANOS can't go any further, so you've effectively extended the piston by a few mm. That was my point. Nothing is said about this critical moment anywhere.

    Here's the missing step that I am trying to bring to everyone's attention: After the VANOS is flush and you bolted it on, grab that sprocket tool and rotate it clockwise as mush as you can, to ensure that the piston is retracted 100%. Only then start tightening the 4 bolts on the exhaust sprocket.

    That was my whole point - retracted piston is important indeed, but in a different step! The fact that you have it retracted before mounting VANOS does NOT guarantee that it will remain in the same retracted position after you manipulated the sprockets during the mounting procedure. Ensure the piston is retracted before locking the timing with the exhaust cam! That's it!
    Last edited by make it easy; 06-19-2019 at 10:52 PM.

  9. #9
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    OK I see what you're saying.

    Just looked over the TIS, while it's fine I don't like the diagrams, they show bolts in place on the exhaust sprocket when they shouldn't be in at all. Also when it's time to put those bolts in they just say to tighten them. They don't show a tool to rotate the sprockets and if I remember correctly it takes a good amount of force to do so.

    Take a look at the bessiansystems guide and see if you like it better.
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  10. #10
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    Found an error in the Besian System guide.

    "Note: Lock pin should not be inserted under chain as it can inadvertently tension chain." should read: not be inserted above chain.
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  11. #11
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    I found my point mentioned in Dr. Vanos installation guide. Step 18, in bold.
    https://cdn.shopify.com/s/files/1/00...88282716730680

    - - - Updated - - -

    Quote Originally Posted by Eric93se View Post
    Found an error in the Besian System guide.

    "Note: Lock pin should not be inserted under chain as it can inadvertently tension chain." should read: not be inserted above chain.
    Yep, it should say above/over, and I don't know how you can "inadvertently tension" the chain by doing so. Maybe he meant damage?

  12. #12
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    Interesting how on this guide (dr vanos) they say to keep the exhaust cam bolts on but a turn loose, besian says to remove them completely, Dr. Vanos cautions not to remove them. Personally I've followed the Besian guide and the only thing I was very cautious of is to not allow the exhaust sproket to come off while working on the vanos, there was no issue.
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