S54 Vanos post Beisan/DV Rebuild Timing Issue

[sapote]

ALL hub bolts - the 6 of them. I am sorry this is not clear, this implies the hubs are already on the sprockets, with all bolts in place but finger tight. this can be done with, or without the spline inserted, does not matter as you need to loosen all of them again to start the assembly, this is just to have visual marks for the torque settings. this works, it was tested, and you can repeatedly reach 14NM and have the marks aligned as long as you don't pull the screws out completely and inserted in another location

as for your comment above, I am sorry but you are not correct. and no, you don't have to bias the crank to achieve timing. if the preload process is done correctly it wont move. there are physical reasons for this which I bullet point bellow

• preload by tightening one bolt at a time skews the hub, which makes the spline to bin and as a result is dragged in separating the piston from the cap
• if preload is done by tightening side by side by small amounts (1/4 of a turn on this bolt is just 0.25mm of displacement), this allows the hub to rotate around the spline as it is being tighten, this wont drag the spline in

there are other potential ways around this, like torque the hubs with the splines in but out enough that they will remained bottomed out as the VNAOS unit is placed. the torque of the VANOS bolts will force it in place making the hubs to spin CCW. Not that I would do this, I told my friend not to try this even when he had been told this worked for his mechanic friend 100's of times. but hey, there are several ways to skin a cat, you pick what you feel more comfortable with.

BTW, we tried the bias approach, and the two times we did it we were off, at which point it was just more effective to do what we did (what I wrote). this sequence allowed the engine to be on time with both pins sliding easily with the bridge flat on the head.

1) Add the final torque mark on the bolts is a great idea.
2) So after pretension the hub with the 2 bolts (across from each other), the hub could move away from the cam/sprocket by 0.25mm max. This means during the final torqueing down the hub, it only can move rearward 0.25mm max and the potential of pulling the piston rearward no more than 0.25mm away from the VANOS cap. The hub cannot pull the piston more than the distance the hub actually moved, 0.25mm. So the idea that when the 2 hub bolts are not evenly torqued down -- total only 1/4 turns -- that cause the hub to pull the piston more than 0.25mm is not right. Say how could the piston moves 0.50mm off the cap if the hub only moved 0.25mm?
3) Here is what cause the final small error: the hub moved 0.25mm at the final torqueing step + the chain slack when the original hubs bolts were loosen. The amount of chain slack depends on how tight the chain tensioner is with no oil pressure. Some has more than the others depending on the oil leaking condition. The M3 vanos instruction doesn't require a special tensioner vs. the non-M cars require this special tensioner to keep the chain tight during the whole process after setting the crank and cams at timing positions. So to compensate for the error, the crank needs to be offset a few millimeter CCW from TDC.

[sapote]

For those that have the timing bridge that off the head on the intake side after complete the VANOS timing procedure, I believe this is mostly due to the chain slack. For whatever the reason BMW instruction doesn’t ask to use a solid chain tension as it is required when doing the timing on non-M cars. As soon as the hubs bolts were released, the sprockets are free to turn and causing chain slack on the pulling side (RH side front view) which leads to the timing small error.

We have 2 choices to correct this: install a hard chain tensioner tool (I used a socket instead of the stock spring loaded piston), or offset the crank pulley 2mm CCW from TDC.
For those that have the timing bridge that off the head on the intake side after complete the VANOS timing procedure, I believe this is mostly due to the chain slack. For whatever the reason BMW instruction doesn’t ask to use a solid chain tension as it is required when doing the timing on non-M cars. As soon as the hubs bolts were released, the sprockets are free to turn and causing chain slack on the pulling side (RH side front view) which leads to the timing small error.

We have 2 choices to correct this: install a hard chain tensioner tool (I used a socket instead of the stock spring loaded piston), or offset the crank pulley 2mm CCW from TDC.

[Arinb12]

How much do you bias and how? I have the same issue and even the torque marks and guide in post 3 give me the same issue. Do I bias the crank and then time up?

[Cubieman]

How much do you bias and how? I have the same issue and even the torque marks and guide in post 3 give me the same issue. Do I bias the crank and then time up?

You can bias the crank or the cams, the cams might be better as you can dail in each individually whereas with biasing the crank you of course affect both cams.

You find out how much you are off, bias the cam(s) that are off (or bias the crank instead), torque things down and hopefully when you spin the engine around a few times your timing bridge sits flush.

As to how much biasing, just measure or eyeball how far your bridge is off the head and compensate that by biasing cam(s) or crank.

As long as your bridge is less than 1mm off the head your fine, I tired to get as flush as possible though.

[Arinb12]

So when you say bias the cams. I should put the engine at TDC but not lock it. Then dial in cam to line with the bridge (tiny lift on tool on intake side when I tighten up) and this is technically biased?

Then rotate a few times and see if it all lines up with bridge when locked at TDC?

Thanks

[Cubieman]

So when you say bias the cams. I should put the engine at TDC but not lock it. Then dial in cam to line with the bridge (tiny lift on tool on intake side when I tighten up) and this is technically biased?

Then rotate a few times and see if it all lines up with bridge when locked at TDC?

Thanks

No, if you want to bias a cam you would lock the crank at TDC1.

Let's says you set your cams up so the bridge sits perfectly flat on the head with the crank locked at TDC1, you torque your hub bolts to spec but after you turn the engine over 4 times and lock at TDC1 again now you find you have a gap between the bridge and head on the intake side of head when checking the intake cam.

In the case of this hypothetical scenario you would re-time but instead of setting up the intake cam so the bridge sits flat you need to slightly advance the intake cam, this means rotating slightly Clockwise as viewed from front of the vehicle.

If both of your cams are off by about the same it would be easier to bias the crank, you either bias the crank ~1-2mm CW or CCW depending on if your cams end up slightly advanced or retarded when you check timing with the bridge.

[Arinb12]

Thank you! And I assume a few mm of bias on the crank is a tiny tiny amount, so it would mean just slight on either side of the I in OIT?

What if when checking intake cam, the gap is on the exhaust side of the bridge?

[Arinb12]

Edited

[Cubieman]

Thank you! And I assume a few mm of bias on the crank is a tiny tiny amount, so it would mean just slight on either side of the I in OIT?

What if when checking intake cam, the gap is on the exhaust side of the bridge?

Correct, when I biased the crank it was just barely outside of the range where the lock could not be inserted. So basically instead of the locking hole being centered in the "window" it would be ever so slightly to one side or the other, depending on how you need to compensate for the cams.

If you have a gap on the exhaust side of head when checking the intake cam this means your intake cam is slightly advanced with crank at TDC1 so you would compensate by having the crank set slightly Counter Clockwise (retarded) of the locking hole when tightening your hub bolts up.

If just one cam is off I would probably just bias that cam, or if both cams are off by different amounts and you are OCD like me bias each cam as needed.

As I'm sure you are aware when you bias the crank you will affect both cams timing, so if one cam checks out (bridge is flat) and the other isn't you'll fix one but then mess the other up if that makes any sense.

[Arinb12]

For those that have the timing bridge that off the head on the intake side after complete the VANOS timing procedure, I believe this is mostly due to the chain slack. For whatever the reason BMW instruction doesn’t ask to use a solid chain tension as it is required when doing the timing on non-M cars. As soon as the hubs bolts were released, the sprockets are free to turn and causing chain slack on the pulling side (RH side front view) which leads to the timing small error.

We have 2 choices to correct this: install a hard chain tensioner tool (I used a socket instead of the stock spring loaded piston), or offset the crank pulley 2mm CCW from TDC.
For those that have the timing bridge that off the head on the intake side after complete the VANOS timing procedure, I believe this is mostly due to the chain slack. For whatever the reason BMW instruction doesn’t ask to use a solid chain tension as it is required when doing the timing on non-M cars. As soon as the hubs bolts were released, the sprockets are free to turn and causing chain slack on the pulling side (RH side front view) which leads to the timing small error.

We have 2 choices to correct this: install a hard chain tensioner tool (I used a socket instead of the stock spring loaded piston), or offset the crank pulley 2mm CCW from TDC.

Where did you use a socket and how?

[Arinb12]

Correct, when I biased the crank it was just barely outside of the range where the lock could not be inserted. So basically instead of the locking hole being centered in the "window" it would be ever so slightly to one side or the other, depending on how you need to compensate for the cams.

If you have a gap on the exhaust side of head when checking the intake cam this means your intake cam is slightly advanced with crank at TDC1 so you would compensate by having the crank set slightly Counter Clockwise (retarded) of the locking hole when tightening your hub bolts up.

If just one cam is off I would probably just bias that cam, or if both cams are off by different amounts and you are OCD like me bias each cam as needed.

As I'm sure you are aware when you bias the crank you will affect both cams timing, so if one cam checks out (bridge is flat) and the other isn't you'll fix one but then mess the other up if that makes any sense.

So if on my exhaust cam when checking after bolting up. I have a lift on the bridge on the intake side, then I need to slightly retard the exhaust cam when timing before bolting up, or advance?

this would mean after a few rotations. And lokxing at tdc1 I should have a flat bridge for the exhaust cam check?

Thanks!

[Cubieman]

So if on my exhaust cam when checking after bolting up. I have a lift on the bridge on the intake side, then I need to slightly retard the exhaust cam when timing before bolting up, or advance?

this would mean after a few rotations. And lokxing at tdc1 I should have a flat bridge for the exhaust cam check?

Thanks!

If you have a gap on the intake side this means the cam is retarded and must be advanced for bridge to sit flat. The same is true for either cam, gap on intake side= retarded, gap on exhaust side=advanced.

Just know the engine spins Clockwise as viewed from front as do the cams.

[maupineda]

If you have a lift on either side you do not want to live with you need to start over, retarding the cam will just make the tool sit flush at that moment, spin the engine and you are back at corner one, this means the spline gear moved on you during mating the VANOS to the head . You must maintain the splines and pistons fully bottomed out at all times. If not, there is a gap and the moment you spin the engine the gap closes by the pistons bottoming out and thus moving your camshaft forward.

You must be very methodical and slow during mating the VANOS to the head so nothing moves. Literally a quarter of a turn per side at a time. Then it all falls in place and even then an ever so slight lift or stickiness to the pins when inserting is fine.

[Arinb12]

If you have a lift on either side you do not want to live with you need to start over, retarding the cam will just make the tool sit flush at that moment, spin the engine and you are back at corner one, this means the spline gear moved on you during mating the VANOS to the head . You must maintain the splines and pistons fully bottomed out at all times. If not, there is a gap and the moment you spin the engine the gap closes by the pistons bottoming out and thus moving your camshaft forward.

You must be very methodical and slow during mating the VANOS to the head so nothing moves. Literally a quarter of a turn per side at a time. Then it all falls in place and even then an ever so slight lift or stickiness to the pins when inserting is fine.

I saw your post on torque markings and then making sure I did it evenly, and followed it it just did not work on both cams. I got intake spot on. Exhaust kept being out, so I biased that cam a tiny tiny bit. Anyway let's try tomorrow with a vanos test and see what happens

[maupineda]

I saw your post on torque markings and then making sure I did it evenly, and followed it it just did not work on both cams. I got intake spot on. Exhaust kept being out, so I biased that cam a tiny tiny bit. Anyway let's try tomorrow with a vanos test and see what happens

i just redid my timing 3 weeks ago as I made a stupid mistake during removal of the VANOS unit to replace the oil pump disc (Beisan warranty) and ended up having to loosening the hubs and as such I had to retime the engine. I followed the TIS document to the T except the parts where you need special tools, i was able to set my timing in one try.

the pins went butter smooth during assembly, after many rotations (maybe 6-8) the pins would still go all the way in, just not as smooth as prior to rotating the engine. And I had the tool sit flush on both ends, so that was good enough to me.

again, i used the torque marks, and I did maybe an 1/8 of a turn at a time evenly during hub and Vanos assembly to ensure everything mated without any skewing.

also I think is key to use the BMW spacers, they cost pennies, i have them and you don’t have to be eye balling 5mm of separation of the Vanos unit to the head. I have used the caliper method but due to space on the Z4M even with the caliper you wonder if it was 100% parallel.

but one thing everyone with OCD (as myself) need to understand is that even if there is a slight lift or shift of the cams, there is plenty of adjustment for the engine management to meet all operational targets.