Failed vanos test post Beisan

[eacmen]

How hard did you crank down on the hub bolts? Compression of the spring washer that much seems unlikely.

Do you have a photo of the back side of where the hub bolts thread into? You should be seeing those bolts protrude as much as the gap you’re seeing between the hub and the disc.

[maupineda]

How hard did you crank down on the hub bolts? Compression of the spring washer that much seems unlikely.

Do you have a photo of the back side of where the hub bolts thread into? You should be seeing those bolts protrude as much as the gap you’re seeing between the hub and the disc.

Without a torque measuring device I don't know. I can assure you I did not go to town as I know 14NM is not much. But I now know that torque by feel here is a very stupid Idea. That is why I came up with the torque marks method for the car I help my friend to do.

[Icecream]

^^Pretty sure mine did not contact the disc when I popped mine open the first time

[Cubieman]

I was bothered so much by not being able to torque the bolts properly with vanos installed that I just about bought a CDI removable head style torque wrench and the head for the hubs bolts, that was going to be about $300.
I followed Sapote's advice and torqued down the bolts with vanos removed. But then my timing issue kept happening and I was tired of taking the vanos off so many times, I got lazy and re-timed w/vanos installed following beisan procedure.
I used this tool at 90° to reach the bolts.

[Cubieman]

One last vanos test before disassembly...

[sapote]

So let me first share some dimensions from the oil pump disc and VANOS unit shaft (measurements taken with digital caliper), so they are close and good for reference only, not to assess tolerances, just the base dimension.

OE Disc height is 20.15mm from the center to the machined groove, and 20.00mm there after
OE Disc piston holes are 9.03mm
OE Pistons are 9.00mm
OE Disc ID is 26.09
Pump Shaft OD is 26.07
Pump Shaft height is 20.50mm

Below are some facts we need to keep in mind

Pump disc as installed is bottomed out to the VANOS unit aluminum casting
The pump disc pistons outer race does not bottom out, nor contact the washer retained by the large c-clip, it just "floats" and spins on the roller bearing
There are ~3mm of clearance between the outer race and the washer
The pump piston side holes are centered on the disc relative the the 20.00mm height, not the 20.15mm

So based on the above, and with the VANOS unit out of the car, the disc and piston racer can move along the pump shaft axial axis up to the point the race is stopped by the washer and c-clip.

Another fact I was missing is that inside the piston holes we have the spring cups, and they have much smaller holes than the holes on the shaft, so the entire aperture is not used / needed for the pump to work, so some offset should be fine. I could not accurately measure the location of the shaft holes relative to its height, but my engineering mind tells me by design they should all line up, or have a very minor offset.

Now here comes the thought I had when looking at my car yesterday with the valve cover removed. We all know the exhaust hub and the disc are in contact, this is evidenced by the marks we always see on the OE disc, and the image below

When I looked at my car yesterday I was surprised to see so much separation, as I do remember my car originally was as per the image above. I did not measure the gap, but is in the range of 2-3mm (Beisan Disc).

what the above means is that the disc can move fore / aft (driver perspective) as the pump operates affecting pump efficiency, this also tells me I have way too much preload on those cup washers, as by design, the hub and disc should be in contact.

the above for sure would be a problem for response time, as the cup springs have too much preload and the same pressure will actuate the cams slower. I am not 100% sure how much the above has an impact to the pump efficiency (assuming all else is to spec), but for sure there is an assembly deviation. so it is KEY to be able to torque those hubs to spec, or there is just too much preload, and in the case of the exhaust hub, separation from the disc allowing axial movement.

So perhaps BMW was not as stupid, and the tab sizes and play relative to the disc were necessary to reduce binding forces as the disc is limited by the casting on one side, and the hub on the other. this is just a thought.

Lastly, I firmly believe the unit has an oil jet that provides oil so the steel disc does not eat through the aluminum, and the step in height is just for that oil to flow out. I think this is an important feature.

So, there you have it, it could be that the issue has a tie to an assembly problem due to the lack of proper tools to torque those hubs appropriately,

Great data gathering and thanks for doing this. I have some thoughts on this.

1) "OE Disc piston holes are 9.03mm, OE Pistons are 9.00mm". This is a little over 0.001"
I think the piston clearance is less than 0.001" . For reference the crankshaft bearing is less than 0.001". I think measure the disc holes with a caliper is not accurate enough.

2) "The pump disc pistons outer race"
To be clear, this is the inner race of the roller bearing -- the small diameter race is always the inner race. The bearing outer race was pressed in for an interference fit. The inner race is floating axially and kept in range by the washer and C-clip.

3) "There are ~3mm of clearance between the outer race and the washer" How did you measure this? 3mm seems to be too much as this would cause the disc 4 smaller holes (less than 3mm dia) to be offset off the center shaft oil grooves.

4) "Another fact I was missing is that inside the piston holes we have the spring cups, and they have much smaller holes than the holes on the shaft, so the entire aperture is not used / needed for the pump to work, so some offset should be fine."
Why do we need the spring cup with hole? I think the cup is to prevent the spring movement and partially blocking the disc hole. Regardless the cup hole vs the disc hole, if the disc can move up to 3mm axially then the disc hole can completely offset and blocked from feeding oil by the shaft holes, since those holes are less than 3mm dia. I have seen OEM used disc with the "cleaned circle" almost off the disc holes as shown in previous post.

5) "this also tells me I have way too much preload on those cup washers, as by design, the hub and disc should be in contact."
I don't think too much preload the hub causing this gap that you saw. No matter how much torque the hub bolts have, the hub cannot move closer to the cam as the hub/sprocket all bottomed on the cam end, and there is nowhere for them to go any further even if one over torqued the bolts to breakage threshold. The spring cup thickness is less than the distance from hub to the cam sleeve. Most OEM discs do make contact with the hub tab's base, but your gap is not caused by too much torque on the hub bolts. As we already know that the disc riding on the inner race has close to 3mm axially float space. In operation, the design allows some pressurized oil flow at the front side of the disc (driver vu) to lube the roller bearing (it has no other means to get lubricate oil). This oil pressure also pushes the disc rearward until it was stopped either by the washer/C-clip or the hub tabs. Did you happen to somehow push the disc by hand forward (it has about 3mm axial plays)?
You cannot compress the cup spring any further even if overtorqued the hub bolts.

[sapote]

One last vanos test before disassembly...

Wow, it got worst with both cams took 530ms to move.

[maupineda]

^^Pretty sure mine did not contact the disc when I popped mine open the first time

but does your disc show marks of rubbing against hub tabs? I bet it does.

[Icecream]

but does your disc show marks of rubbing against hub tabs? I bet it does.

I'd have to pop it open again to see.

[sapote]

I'd have to pop it open again to see.

I'm sure the disc rubbing the hub in operation. This is by design to stop the disc/inner race moving rearward any further. The bearing inner race cannot rely on the washer/C-clip to stop it as this will wear out the components. The reason engineer needed the washer/C-clip is to prevent the inner race fell off if for some reasons the disc pistons jumped off the inner race groove.

[Shonky]

Now here comes the thought I had when looking at my car yesterday with the valve cover removed. We all know the exhaust hub and the disc are in contact, this is evidenced by the marks we always see on the OE disc, and the image below

When I looked at my car yesterday I was surprised to see so much separation, as I do remember my car originally was as per the image above. I did not measure the gap, but is in the range of 2-3mm (Beisan Disc).

This is mine which is completely untouched. VANOS has never been off to my knowledge. Factory disc, decent pressure (slightly low) and good VANOS test times.

Looks like the disc surface is not touching the hub but you can see wear marks too. Smaller gap than yours and none of my multiple photos really show it clearly (I was mainly looking for cracks).

These were taken 8 minutes apart just turning the crank by hand. I have the valve cover off now (was doing valve clearances first). I will look again tonight.

[sapote]

This is mine which is completely untouched.

During engine stopping the disc might have moved forward with lower oil pressure.
100% sure during operation the disc never touched the vanos body (if disc moved forward) as this would leave a wear circular path on both the disc and the vanos body. I never seen one.

So turning the cam by hand can move the disc away from the hub tabs, randomly based on the roller bearing natural setting.

[Icecream]

^^^I didn't want to mention it before (in case I remembered incorrectly) but that is how I remember mine. I wouldn't call it wear marks but there was less oil staining in those locations.

[Shonky]

During engine stopping the disc might have moved forward with lower oil pressure.
100% sure during operation the disc never touched the vanos body (if disc moved forward) as this would leave a wear circular path on both the disc and the vanos body. I never seen one.

So turning the cam by hand can move the disc away from the hub tabs, randomly based on the roller bearing natural setting.

Right, so why the concern about the gap to the hub then?

[sapote]

Right, so why the concern about the gap to the hub then?

I tried to tell the poster his concern has no ground.