2nd Gen R56 Cooper S Most liked posts in thread: Rising crankcase pressure when using BSH OCC?

I had the same concerns and reconnected the rear.... My OCC is connected to the turbo inlet routing.... This keeps the turbo, inter-cooler, and various sensors protected that lead to the intake manifold. The rear connection will still allow oil fumes through to the intake, but the total amount will be reduced by the quantity collected by the lone OCC....

I haven't come up with a good OCC location for the rear connection.... I'll probably leave the rear as the OEM connection and just deal with the carbon blast as necessary....

When I did have the rear connection blocked for a short period of time, I noticed some oil seepage around the valve cover, indicating pressure buildup.... Since going back to the rear OEM connection, the seepage has stopped....

One other thing I noticed.... In my case my OCC has a stack of fine perforated discs in the OCC.... This provided the phase change to the vapors that allow the change of the oil mist into droplets that are then collected in the can.... It's not a good idea to just use the syringe to suck out the collection..... If these discs get clogged with the accumulation.... and they will.... the OCC can stop functioning and in severe cases could be blocked causing valve cover back pressure.... In my case, I pull the can... remove the accumulation.... flush the OCC with solvent.... followed by a soap and hot water rinse.... and then re-install the can.... This puts the can back into "as new" condition....

 

Lotsa opinions on this subject. I'm convinced that driving habits / style make all the difference. Here's a link to my experience with OCCs http://www.motoringalliance.com/forums/cooper-s/17801-how-screw-up-occ-install.html
In summary I used a dual OCC from Saikou Michi and my problem went away --- no permanent damage to the seals.

 

Just read pages 130-53 & 130-54 of the Bentley manual , it is pretty obvious.

Dave

 

I have a BSH oil catch can installed on the PCV line to the turbocharger with the PCV line to the throttle body blocked off with a BSH dual boost tap. I did this soon after buying my car in 2010

I haven't had any oil seepage, increased oil consuption or any other indication of increased crankcase pressure.

The turbocharger inlet is always under negative pressure whenever the engine is running. There is no reason that crankcase pressure would increase with the throttle body PCV hose blocked off, unless the PCV valve in the head cover is faulty.

Dave

 

Sorry Dave, I can't agree with this --- it's in direct contradiction to the Bentley Manual and info from the OP's "competent mechanic". Can't argue with the rest of your input ---

 

When you block off the throttle body PCV line, the PCV valve acts as if the engine is under boost all the time, the check valve in the head cover outlet to the turbocharger opens and vents the crankcase pressure to the turbocharger inlet. This agrees with the PCV operation explanation in the Bentley manual. My personal experience with my installation verifies this. There are hundreds of BSH catch cans installed with the PCV line to the throttle body blocked off, with no problems of increased crankcase pressure.

Yes, there have been a few cases of increased crankcase pressure and increased oil consumption, but the only explanation I can see is a faulty PCV valve, that doesn't allow the crankcase pressure to vent into the turbocharger inlet.

Dave

 

Where did this bit of info come from?

 

BINGO! Reading in knowledge, the more you know......

Just goes to show no matter what generation MINI you have the Bentley Manual is a must have tool.

 

OK, you've taken a basic description of a complex system, and made some assumptions on how / why it works "better". So, how do you explain why the changes you're defending don't work for all of us, when our OEM connections work correctly --- no excessive oil consumption? I'm suggesting "driving habits / style" --- cruise control vs stop and go (or constantly changing manifold pressure).

 

I have had the BSH catch can on my '09 for two years and 30,000 miles with the PCV blocked off with no ill effects. I don't consume oil or drain much fluid from the can either. It works as advertised IMHP.

 

It's not a complex system, it's a PCV valve.
If you block one hose, either mechanically by plugging it, or as designed by increasing the manifold pressure, which closes the check valve, you are doing the same thing. The pressure will be released through the other hose to the turbocharger inlet. If you have a defective headcover, that pressure will not be released and the car will leak oil out the seals and gaskets associated with the crankcase.

It has nothing to do with driving style.

Dave

 

Since Dave can't / won't answer this question, will someone else offer an explanation?

 

Again, you have a defective head cover/PCV valve

I have explained it over and over, what don't you understand?

Dave

 

This is going nowhere! In the interest of the OP, I’m dropping my subscription to this thread. Hopefully, there’s something useful for him here.

 

I think it is obvious why your PCV valve causes over pressure in your crankcase, when you block off the hose to the throttle body. The check valve to the turbo is not opening or the passage to the check valve is blocked, giving the crankcase gasses nowhere to go.

When you put it back to stock, your crankcase gasses are vented to the throttle body, the excess pressure goes away. If you have a boost gauge installed, you'll see that 90% of driving is under zero boost, the PCV valve is venting to the throttle body most of the time, you don't notice that the line to the turbocharger is not functioning. The times when you do have high crankcase pressure could be measured in seconds, not enough time for a leak.

Take your car to a track and keep it under boost most of the time, your oil loss will come back, because the check valve on the hose to the throttle body will close, just like when you plugged it, your pressure relief to the turbocharger inlet is non-functioning, so the crankcase will pressurize.

Dave

 

I'm still looking for a detailed explanation that's probably only available from a Mini engineer. In the meantime, Dave's explanation works. Couple months ago, I was traveling over the Sierra's from Placerville to Lake Tahoe on hwy 50 where most of the hwy is one lane each way, with occasional passing lanes. Having no patience for sightseers, I used the passing lanes A LOT --- getting up to 90MPH or so --- pedal to the metal! Next day, oil was ½ qt low --- per Dave's explanation.

So, I bit the bullet and changed the valve cover. Since then, after terrorizing a couple kids in their "rice rockets", I check the oil and find no excessive consumption. Still needs more hard driving to be sure, but it's probably fixed --- finally. I'll find out for sure at MiniThunder V in mid-Feb.

Meanwhile, I apologize to Dave if I offended him. I read a lot but only understand some of it. It's no fun getting old! Now to go edit my "How to screw up an OCC install" thread.

 

All good info here....