08 r56s MT, lots of blue smoke while rev matching when I down shift. Does not happen every time, and only happens once the engines hot, and usually only when downshifting into high revs. Also happens sometimes hitting the gas after engine breaking down hills. Did a compression test and each cylinder came back 150 psi. Last owner said turbo was recently replaced, so about 10k miles ago. I think it is the valve seals giving me issues, any ideas or advice would be appreciated.

 

I'd do some troubleshooting of the PCV valve. I'm not as familiar with the N14 engine but on the N18 it's integrated into the valve cover and is known for wearing out and failing.

Search on that, you'll find a lot of testing and replacement info.

 

PCV on the valve cover which is integrated. So new valve cover.

Once that's replaced and it still does it, its the valve stem seals.

 

Thank you, Im sorry i forgot to mention i have already replaced the valve cover about 3k miles ago in hopes that it was the pcv system. I replaced it with:
n14 valve cover

I assumed it would be an ok aftermarket replacement. I guess its time to order a valve spring compressor lol

Edit: i have also added a catch can on the intake side before the turbo

 

Yeah, usually smoke on deceleration is valve stem seals. N14 engine will pull higher vacuum on deceleration. Higher vacuum in the intake will suck oil past worn stem seals.

 

Sounds like the valve stems.

 

One test o regular engines is to let it idle for a long time. It will then draw oil past stem seals and cause smoke when you first start off. However, with the valvotronic system, that isn’t true with Mini engines as they don’t have the strong vacuum at idle. Gearing down might have a dramatically different result.

Peter

 

Sounds like a compression and leak-down check are needed.

 

The N14 engine, of which is in the OP’s car, does create vacuum in the intake manifold. The later N18 engines do not.

 

My MINI has the N16 engine with Valvotronic which doesn't need to generate any vacuum as there isn't a reason to ever close the throttle since the valves do the limiting of flow to the cylinders.

However, it does have a throttle so I'm not actually sure when the throttle is used. Maybe the valvotronic is too slow in opening and closing.

IDK.
Peter

 

The throttle is a the back up mode for air flow control in case one of the various sensors in the Valvetronic system or eccentric shaft motor fails. If the Valvetronic system is too slow, it will result in an associated DTC.