Timing s54 after vanos rebuild installation

[sapote]

The thing is that due to the helical cut splines, vanos piston moves linear to rotate the cam, and when we turn the cam then it could also move the vanos piston linearly. So even with the hub bolts loosen, turning the cam CW could pull the vanos piston.

Another point is that, what if the cam timing is off (i.e the bridge off the head by 2mm on the exhaust side) was due to the vanos piston was not its most retarded position (off from the cap end travel)? And so in this case, loosening the hub and turn the cam to the correct timing still ended up wrong because vanos is not its most retarded position.

So how does the OP know if the vanos pistons are at their most forward position when he just loosen the hub and correct the cam timing? Obviously he could do a trial-error of loosen the hub and correct the cam, then do a final turning the crank 2 turns then check the cam bridge at TDC, and repeat until the timing is correct.

[JokerElite]

I’ll be going with the method that requires removal of the VANOS unit as it seems to leave less opportunity for error.

Going to take advantage of the warmer weather and will tackle this in the evening. Appreciate all the tips and will certainly report back.

[JokerElite]

Reporting back, I eventually reinstalled the VANOS unit and tightened the top 4 intake and exhaust hub bolts. I checked the timing right after and the dowel inserted into each camshaft smoothly. Then I rotated the crank once to TDC (to access remaining bolts) and performed a timing test. I noticed the dowel required slight pressure to fit into the exhaust camshaft hole and would line up with the intake camshaft hole but would not go in. After tightening the remaining bolts, I rotated the crank once more to TDC (cams back at ~45°) and performed another test and the dowel goes into both holes with slight pressure.

Is this fine?

If so, can I back out the VANOS unit a little to slip in the new gasket or would this ruin timing?

[maupineda]

Yes, is fine. We all want smooth as butter after spinning the engine a few rotations but the reality is that there is some slack on the chain, yet you could wiggle the cams with the 24mm spanner and the pin will go back in smoothly but rotate again and you will find the same condition again. Remember, the cams can even be out by a couple of degrees and the VANOS still be fully operational. Dont loose sleep on it.

[heinzboehmer]

+1 to what Mau said

Also, as long as you don't loosen the hub bolts now, the timing will not change. If you want, you can take the VANOS fully off by unthreading the splined shafts from the pistons and the timing will remain the same.

[heinzboehmer]

I looked into the "checking timing" thing out of curiosity and TIS does have a section on doing that. It says to loosen the hub bolts and rotate the cams into their correct positions.

However, it also says to first connect a special tool onto the VANOS unit to actuate the pistons. This fully retards the cams (by moving the VANOS pistons all the way towards the front of the engine), which is essentially the same thing you are doing when you bolt the VANOS down onto the engine. The cams are not fully retarded when the engine is shut off, as the DME moves them into the optimal position for the next engine start.
Without ensuring that the pistons are at the limit of their travel (cams fully retarded), checking timing doesn't really make sense. So unless you have a way to ensure this, it's best to take the VANOS unit off and put it back on.

[JokerElite]

Very interesting. I wonder if they still sell that device. I ended up loosening the unit a little bit to slip the new gasket on and the timing still appeared to be okay. Will be doing a valve adjustment today before putting the rest back together.

[eacmen]

Very interesting. I wonder if they still sell that device. I ended up loosening the unit a little bit to slip the new gasket on and the timing still appeared to be okay. Will be doing a valve adjustment today before putting the rest back together.

https://www.fcpeuro.com/products/bmw-tester-83300493429

[sapote]

https://www.fcpeuro.com/products/bmw-tester-83300493429

30 seconds cranking is a long time. Where do you connect this switch to? I rather buy a dinner.

[eacmen]

30 seconds cranking is a long time. Where do you connect this switch to? I rather buy a dinner.

Yeah not recommending anyone buy it but the op asked.

I believe you connect it directly to the VANOS connector and supply it 12v from a battery source.

[sapote]

I believe you connect it directly to the VANOS connector and supply it 12v from a battery source.

So you turned on the switch to active the vanos solenoids and then crank the starter for 30sec? I thought somehow it also activates the starter to crank engine.

[eacmen]

So you turned on the switch to active the vanos solenoids and then crank the starter for 30sec? I thought somehow it also activates the starter to crank engine.

I will admit I don’t know, never had the privilege to use the tool.

[heinzboehmer]

So you turned on the switch to active the vanos solenoids and then crank the starter for 30sec? I thought somehow it also activates the starter to crank engine.

I think you're supposed to crank the engine to build up oil pressure, then use the tool to activate the solenoids.

There's others VANOS procedures on TIS that use that same tool, but they have you provide a source of compressed air to the VANOS with it off the car. Those don't have you crank the engine (not that it would do much with the unit off of the car anyway).



Sidenote: pretty sure "11 6 050" is a typo and should actually read "12 6 050". "11 5 050" seems to be something else.

[sapote]

I think you're supposed to crank the engine to build up oil pressure, then use the tool to activate the solenoids.

This makes sense, but it depends on having a good accumulator tank.

[maupineda]

You dont need to crank to build pressure, you need to connect a compressed air supply and power the tool while connected to the VANOS solenoids so you can operate those and fully retard the cams and then be able to disassemble it, or to time it for that matter.