Failed vanos test post Beisan

[Cubieman]

Based on this video it should take about 2 minutes to drop from 40bar to 20 bar. Too short time could mean big leak from the disc (center hole has too much clearance), or bad accumulator. If it is a known good ACC then we can say the leaking disc is the cause.
https://nam3forum.com/forums/forum/m...pressure-tests

The sure way is to remove the disc and check it alone (no pistons riding on roller bearing) on the center shaft: rock the disc around and one should not feel any plays.
To check the pistons fit in the disc: slide the piston in with no spring and it should feel zero plays when rocking the piston radially, then with finger seals off the piston exhaust small hole, pushing the piston in and it will bounce back as compressed air is not leaking. If air is leaking then the hole is too large for the piston. Piston also should slide smooth and freely.

Thanks, this is more great information. I will re-test and check this parameter. I don't like letting the car sit for 20min idling up to temp but I still have the gauge hooked up and will give it a go.
Raj is sending me an OE disc and I plan on swapping that out as something must be done to increase vanos pressure and from all indications so far its either or worn shaft, or disc related.

Seeing as I didn't do a pressure test beforehand I cannot validate that the disc is at fault, but my DIS test with vastly superior response times before disassembly points to a higher pressure than 40bar in my opinion.

[sapote]

Btw, someone recently said the stock disc has the brass center hole acting as bearing on the shaft. No, the disc is a one piece hard steel including the center hole as bearing (I tested with a magnet). There is high oil pressure (115 bar normally) between the disc hole and the shaft and so it works as bearing and very little wears after over 100K miles. The shaft has 2 circular grooves opposite at each other wrap around the shaft inline with the pistons output small holes: one groove to supply oil to the pistons on their intake stroke, and the other groove is for exhausting the compressed high pressure oil out of the pistons. Each groove is channeled to the oil gallery in the vanos body.

[180SXTCY]

subbed to this thread. A lot of good useful information being presented.

[maupineda]

Btw, someone recently said the stock disc has the brass center hole acting as bearing on the shaft. No, the disc is a one piece hard steel including the center hole as bearing (I tested with a magnet). There is high oil pressure (115 bar normally) between the disc hole and the shaft and so it works as bearing and very little wears after over 100K miles. The shaft has 2 circular grooves opposite at each other wrap around the shaft inline with the pistons output small holes: one groove to supply oil to the pistons on their intake stroke, and the other groove is for exhausting the compressed high pressure oil out of the pistons. Each groove is channeled to the oil gallery in the vanos body.

That was me, you can see it for yourself on these images. it more than likely was pressed and then machined down to the final size and finish





you can see the two material layer on the inner race side hole

[sapote]

I see the line in the drilled hole which I didn’t see in my disc. Optical illusion?
Why there is no similar line in the other holes in both pictures? And the newly drilled holes have a uniform shiny material instead of two different shades steel vs brass?
1)The holes must be hard material to be driven by the hub tang sharp edges, and brass cannot be 50% of the holes.
2) The high pressure 115 bar small focused oil jet flow out of each piston would enlarge the brass holes in short time.
3)It’s magnetic material so cannot be brass.

[sapote]

Seriously I believe the disc is a one piece hard steel but don’t know why BMW machined the deep circular groove on both sides of it for some reason, making it looks like 2 pieces pressed together.

Another interesting point is why the intake and exhaust holes and grooves on the center shaft are offset slightly off the disc pistons oil holes instead of perfect center, on my VANOS. One can see the offset by a clean circular line (jet cleaned by the 115 bar oil jet) inside the disc center hole is about 0.5mm forward (driver view) and not centered to the disc 4 small holes. Is this caused by too much plays between the big roller bearing inner race and the circular lock ring and washer, allowing the disc to shift rearward 1mm, and a thicker washer will center the disc holes to the shaft holes for better pump efficiency?

Edited: 0.5mm and not 1mm which is too much.

[maupineda]

Seriously I believe the disc is a one piece hard steel but don’t know why BMW machined the deep circular groove on both sides of it for some reason, making it looks like 2 pieces pressed together.

Another interesting point is why the intake and exhaust holes and grooves on the center shaft are offset slightly off the disc pistons oil holes instead of perfect center, on my VANOS. One can see the offset by a clean circular line (jet cleaned by the 115 bar oil jet) inside the disc center hole is about 0.5mm forward (driver view) and not centered to the disc 4 small holes. Is this caused by too much plays between the big roller bearing inner race and the circular lock ring and washer, allowing the disc to shift rearward 1mm, and a thicker washer will center the disc holes to the shaft holes for better pump efficiency?

Edited: 0.5mm and not 1mm which is too much.

https://nam3forum.com/forums/forum/m...-disk-solution

it is even in the replica's product information. is not an optical illusion, the color is different because the material is different, I would not know for sure if it is brass, but is not one single piece of steel.

the machined grooves do not denotate the two material joint, the top one may be there for manufacturing reasons, the one on the back denotate a step in height of around 0.2mm. no OE would spend time and money if these features that add machine time were not 100% necessary. I work for an OE in PD, and we eliminate anything we can get away without if not needed for performance, spec, durability, etc.

The bushing is much closer to the inner race, and is very thin (download and zoom in), so it was pressed in and machined after to the spec. this will give you a better idea what I am talking about

https://www.youtube.com/watch?v=KKiHgBhW8UQ

[sapote]

https://nam3forum.com/forums/forum/m...-disk-solution

it is even in the replica's product information. is not an optical illusion, the color is different because the material is different, I would not know for sure if it is brass, but is not one single piece of steel.

You're right. I thought you meant the inner brass core separated form the disc by the circular groove on both sides and so when I saw the magnet was attracted to it I said it must be steel which is correct. So the brass is just the 1mm or so thin layer for the inside diameter. It should have ring the bell when I saw the "jet cleaned" circular line with brass color inside the hole -- I thought it was from the engine oil tarnish. I will use an exactor knife to test the brass bush at the chamfer edge.

"the machined grooves do not denotate the two material joint, the top one may be there for manufacturing reasons, the one on the back denotate a step in height of around 0.2mm. no OE would spend time and money if these features that add machine time were not 100% necessary."

On the 0.2mm step on the front side (driver vu), is the higher side closer to the center? It's interesting as the disc front side is not touching the VANOS and so why to have the fancy 0.2mm step? The disc to VANOS clearance is enough for the escaped oil to get out via the roller bearing (and lube it), so why the needed step?



"Beisan Systems has manufactured an S54 vanos oil pump disk.
The Beisan oil pump disk is a replica of the BMW oil pump disk, but has smaller diameter face holes.
The smaller face holes fit both the BMW exhaust hub tabs and Beisan exhaust hub tabs, leaving .05mm play."

I would think 0.05mm or 0.002" tang/hole clearance is quite tight. You had used the BS disc before and do you remember it was hard to install the VANOS with such tight hub tangs to the disc holes? I am not sure the build up tolerance from the EX cam to hub to disc to VANOS body and the head dowel pins (cylinders) can be within this 0.002" tolerance. If the disc and the tangs are off more than 0.002" then this places a lot of pressure on the delicate small roller bearing or even crack the hub tangs.

Beside, there is no way a user can tell if the holes/tangs is an interference fit as he just cranked up the torque when bolting the VANOS to the head. He won't be able to tell if they are off by 0.010" unless one rotates the cam without any valves nor chain to test the free motion. How do we know if they are fighting in there?

[maupineda]

^^^ The installation of the disc to the hub was not difficult at all, in fact there was still some play that could be felt and heard by mating them by hand before assembly, I even thought they could be tighter but with thermal expansion I assume is best to still have some lash.

upon assembly i remember the hub tabs fell in place with the disc without rubbing or struggle.

but as you said, without all these details up front the shop or DIY’r will just crack on. It happened to me and I came to learn more about this as I wanted to know why my car is low on pressure, and still is, just bought the seals kit to rebuild my spare VANOS and had the disc redrilled already.

This will give me the opportunity to measure and compare OE V Beisan. I was, at a point, going to buy a whole new valve body at ~700 bucks but rather got a spare VANOS since nothing indicates mine are bad. As the OP’s, my car passes leakage, timing is spot on, but response time is slow at 300ms despite the Z4M test logic being at 2k rpm. ILO 1.5k.

[LukesM]

Cubieman, how did the pistons feel on the BS disk? I had 2 that felt too tight. Raj sent me some spares and I found 2 that felt similar to the fit on my oe disk. I sent the tight pistons back to Raj. I haven’t performed any vanos or pressure tests but car feels good.

[Cubieman]

^^^ The installation of the disc to the hub was not difficult at all, in fact there was still some play that could be felt and heard by mating them by hand before assembly, I even thought they could be tighter but with thermal expansion I assume is best to still have some lash.

upon assembly i remember the hub tabs fell in place with the disc without rubbing or struggle.

but as you said, without all these details up front the shop or DIY’r will just crack on. It happened to me and I came to learn more about this as I wanted to know why my car is low on pressure, and still is, just bought the seals kit to rebuild my spare VANOS and had the disc redrilled already.

This will give me the opportunity to measure and compare OE V Beisan. I was, at a point, going to buy a whole new valve body at ~700 bucks but rather got a spare VANOS since nothing indicates mine are bad. As the OP’s, my car passes leakage, timing is spot on, but response time is slow at 300ms despite the Z4M test logic being at 2k rpm. ILO 1.5k.

I also tested by hand the Beisan disc to hub before install, it was definitely not and interference fit, just a tighter fit. Also during installation I forgot to index disc>hub correctly so the vanos would not push on, I correctly indexed the pump disc and it went it without issue.
I am hoping a different disc will fix my issue, otherwise I am just likely to buy a different (tested on engine to pressure/spec) vanos unit and be done. Although at this point it would be a shame to not learn to cause of this problem so it could be better understood.

[Cubieman]

Cubieman, how did the pistons feel on the BS disk? I had 2 that felt too tight. Raj sent me some spares and I found 2 that felt similar to the fit on my oe disk. I sent the tight pistons back to Raj. I haven’t performed any vanos or pressure tests but car feels good.

I honestly payed zero attention to this, I was so focused on following the Beisan instructions this didn't cross my mind.
I do remember that the pistons did not stick and I did turn the disc by hand CCW and heard a distinct "suction/pumping" noise. I wish I would have payed more attention to fitment, I will be looking over this carefully once I have a different disc and everything is apart on the bench.

[LukesM]

I honestly payed zero attention to this, I was so focused on following the Beisan instructions this didn't cross my mind.
I do remember that the pistons did not stick and I did turn the disc by hand CCW and heard a distinct "suction/pumping" noise. I wish I would have payed more attention to fitment, I will be looking over this carefully once I have a different disc and everything is apart on the bench.

You would have noticed if you had the problem I did. One wouldn’t even fit. Replaced that one and another that felt like it had some friction. I used motor oil to lubricate during this process.

[sapote]

^^^ The installation of the disc to the hub was not difficult at all, in fact there was still some play that could be felt and heard by mating them by hand before assembly, I even thought they could be tighter but with thermal expansion I assume is best to still have some lash.

upon assembly i remember the hub tabs fell in place with the disc without rubbing or struggle.

but as you said, without all these details up front the shop or DIY’r will just crack on. It happened to me and I came to learn more about this as I wanted to know why my car is low on pressure, and still is, just bought the seals kit to rebuild my spare VANOS and had the disc redrilled already.

This will give me the opportunity to measure and compare OE V Beisan. I was, at a point, going to buy a whole new valve body at ~700 bucks but rather got a spare VANOS since nothing indicates mine are bad. As the OP’s, my car passes leakage, timing is spot on, but response time is slow at 300ms despite the Z4M test logic being at 2k rpm. ILO 1.5k.

I would expect the disc and hub tangs insertion on hands is easy even with 0.002" clearance, and also during installing the VANOS to the head before the vanos registered by the head's 2 dowel pins, since the vanos has tons of clearance on the 10mm bolts to wiggle around and mate with the hub tangs. However, as the vanos registered by the dowel pins, things starts tightening up, and the installer will never know that he has to turn harder on the mounting bolts due to the tight dowel pins or due to the disc holes to hub tangs small misalignment, as anything more than 0.002" will cause metal against metal. I have heard some people even thought about removing the dowel pins to get the vanos on.

[Cubieman]

I would expect the disc and hub tangs insertion on hands is easy even with 0.002" clearance, and also during installing the VANOS to the head before the vanos registered by the head's 2 dowel pins, since the vanos has tons of clearance on the 10mm bolts to wiggle around and mate with the hub tangs. However, as the vanos registered by the dowel pins, things starts tightening up, and the installer will never know that he has to turn harder on the mounting bolts due to the tight dowel pins or due to the disc holes to hub tangs small misalignment, as anything more than 0.002" will cause metal against metal. I have heard some people even thought about removing the dowel pins to get the vanos on.

So is the suggestion that the disc/hub tangs could be pressed together too tightly causing binding OR maybe pushing pump disc off its "oil grooves" on shaft as a result?