Is this why Vanos oil pump fails?

[poss]

Closeup of my Vanos oil pump (after a paltry 54k miles). Note the clear indentation (which is also on the other side of the hole) caused by the tab on the spline impacting on the hole - adding at least another .5mm of gap that increases further the accel/decel impact of the tab on the hole. No wonder the tab eventually fails from metal fatigue

[terra]

That’s the leading theory. I’m of the opinion that BMW’s decision to remove the one-way valve at the pump outlet is what allows those accel/decel cycles to manifest. That is the major difference between the s54 and s50b32 and s62 vanos systems.

[sapote]

Closeup of my Vanos oil pump (after a paltry 54k miles).

Were you the driver of those 54K miles, and what is the typical engine rpm range? I think more rpm changing in a quick pattern , rhythm, would cause more hammering on those disk holes. I would think the disk spinning speed is more stable than the cam hub as the regulated output oil pressure is stable.

[poss]

Were you the driver of those 54K miles, and what is the typical engine rpm range? I think more rpm changing in a quick pattern , rhythm, would cause more hammering on those disk holes. I would think the disk spinning speed is more stable than the cam hub as the regulated output oil pressure is stable.

No. I only put the last 14K on her - most of it being inter-state highway cruising (with some spirited back road driving here and there). However, it's a 'vert - unmolested and unlikely to have seen much (if any) track time. I'd imagine oil pumps on higher mileage and tracked cars would look even worse.

[sapote]

Before the hub tabs broke, you should have the disk drilled with 2 new and smaller hole with about 0.010" clearance to the tabs.

[poss]

Before the hub tabs broke, you should have the disk drilled with 2 new and smaller hole with about 0.010" clearance to the tabs.

I didn't remove the oil pump just to take it's photo . Sent off for drilling today.

[sapote]

It's very critical to have the new drilled holes be 180 degrees in line with the disk center, and equal distance.

[LatinSkllz]

Who’s re-drilling the disc for you?


Sent from my iPhone using Tapatalk

[poss]

Who’s re-drilling the disc for you?


Sent from my iPhone using Tapatalk

I have a friend with a machining workshop here in Australia. Determining equal distance from centre is easy - the existing circular groove marks it - just need to ensure 2 new holes are precisely opposite. Original holes were 10.5mm. Drilled new 9.8mm holes - only a fraction of the play dry (so add some oil and the play will be virtually nothing).

Vanos all reassembled and working like a charm.

[Shonky]

Mine had hardly any wear after about 100k kms. Nothing like that photo.

Yes smaller holes is the theoretical fix and I've not read of anyone having a failure with a modified pump disc (genuine redrilled or a Beisan one). That doesn't prove the fix but does support it.

That said, once moving I would not expect the free play to be much issue. The disc will "drag" as it's pumping and the tabs should always be pushing it around. I don't see how the disc would ever get ahead of the tabs and then end up being hit again. However the tabs do break and some discs like yours end up with significant wear. Perhaps if they start to wear a bit, it accelerates as the free play gets bigger.

[poss]

Mine had hardly any wear after about 100k kms. Nothing like that photo.

...once moving I would not expect the free play to be much issue. The disc will "drag" as it's pumping and the tabs should always be pushing it around. I don't see how the disc would ever get ahead of the tabs and then end up being hit again...

It's called 'momentum'. The disc is quite weighty and wants to keep its momentum (same RPM) when the camshafts decelerate because of an aggressive down gear change - causing the tabs to smash into the rear of the oil pump drive holes, and the opposite occurs for aggressive acceleration - the pump disc wants to stay at the same speed but the camshaft says otherwise by slamming the tabs onto the opposite side of the drive holes.

Although they're quite different parts of the car, it's the same fundamental metal fatigue equation that cause both the oil pump tabs and the RACP to fail (at least in terms of the subframe rubber bushings deteriorating and causing them to hammer the RACP) - Number of stress impact cycles and the force of the impacts. If you drive the car hard regularly you are more likely to experience stress fractures in both the RACP and the Vanos oil pump tabs.

[Tbonem3]

There's more to it than just the dimensions of the disk's holes. My 124k 02/2002 s54 had zero, I mean zero, markings whatsoever. Literally looked brand new.

[jet_dogg]

I don't think the disc issue is fully understood and everything is just conjecture on the internet.

[bloung5]

Just had my vanos overhauled at 156k miles, from the original factory setup. To my surprise, no damage was present. Guess I got lucky.

[Obioban]

There's more to it than just the dimensions of the disk's holes. My 124k 02/2002 s54 had zero, I mean zero, markings whatsoever. Literally looked brand new.

Mine also had no deformation at 120,000 miles (all of which were driven like I stole it, I might add-- so any notion that going easy on the car causes this to not happen is misguided).

That said, after a decade of people installing the smaller hole Beisan disk, with not a single known failure, I feel like the solution is reasonably proven out at this point.