Drain back valve broken... run it?
 

The drain back valve plunger broke while doing an oil/filter service.
Two little tits snapped off and it doesn't hold in place anymore.

I've got an 160km round trip I need to make tomorrow.

What's the purpose of this plunger?
To stop oil starvation on startup?

What if I only have two starts during the trip?
Is the wear limited to start up?

Thanks for helping me avoiding running a shittier vehicle for the trip tomorrow :p

Got to be careful. Could starve engine idle. Get aftermarket one from Outmotoring.

Got it. I'll leave it in the driveway tomorrow then.

I need to understand everything...
Can someone explain to me why it's a danger only at idle?

Side note: I would recommend pulling the housing and the oil cooler to remove the old plunger and replace it with a new one. When mine was out there were little plastic tabs that were "missing". After several flushes, I found the "missing" plastic that had been hidden (likely lodged) in an inside corner of these parts. While you have them off, it's a good time to install new oil filer housing gasket and new oil cooler gaskets as well.

And since you'll be in the general vicinity, you might want to consider a new timing chain tensioner if you've not already replaced. It's easier to do with the housing out of the way.

at idle, particularly hot idle, the oil pump is fighting against gravity to keep oil in the filter and flowing beyond it. It's arguably even more of a danger once the car is shut off. The device prevents oil from gravity draining out of the filter canister back into the motor and down to the crankcase after shut off, leaving the filter empty. With an empty filter canister, this would mean "dry" starting the engine without an immediate flow of oil from the filter because the pump was just re-filling the cannister for the first several revolutions of the motor during cranking and initial start-up. Spin-on filters have this anti-drain back valve feature built in for other cars; naturally on MINIs it is a permanent, vulnerable part of the car, because BMW...:roll:

It's also made out of hearty government-mandated recycled German plastic, and we all know how well that holds up over time (see: coolant expansion tank, brake/clutch reservoir, heater hose connectors, supercharger intake plenum, clutch master / slave cylinders, vacuum and clutch lines and connectors, etc) . Below is a link to the 3D printed replacement solution mentioned above which so far seems to be well received, performing (and surviving) as advertised. It should be noted that before its invention, and even now, a factory drain back valve wasn't / isn't available as a separate part and when it broke it necessitated replacing the whole filter housing assembly to the tune of around $400, once again because BMW.:mad:

Here is the current solution; a bargain at $29, would overnight it if you have time before your trip:
https://www.outmotoring.com/MINI-Coo...rep_12345.html

L
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Thanks for the detailed explanation.
I was banging my head thinking why wouldn't it just be a problem on startup?

I've bought that part you linked.
I'm up in Canada, so no overnight shipping.
The closest to that is 2-3 days and $56usd just for the shipping.
So I ended up paying for the cheapest shipping and bought the Dorman 904-261 part locally.

Gonna try it out, and if it doesn't work, I've got the 3D printed part on the way.

Yep dorman part is shared.

Make sure you get pieces out that broke off.

Dorman does not work. Do not use. Only aftermarket one that works is from Outmotoring.