Since I promised to post this here it is. But I do so with some trepidation and more than a few disclaimers.

1. If your vehicle is under warranty I wouldn't consider this.
2. If you don't have the Bentley Mini manual don't try this. You'll need the torque values it contains.
3. If your not able to work over an open engine without dropping things you might want to pass on this one.
4. If your not comfortable with the thought of breaking a tap off in your cylinder head and have no clue how to remove one if you did... don't even think about.

There now that that's out of the way let's get on to the good stuff. Unlike our N14 friends we do not have the option of blanking off the rear PCV port with some plastic caps. We do however have the small advantage of having a vanos on the exhaust cam that reduces valve overlap and carbon buildup. Key word is reduces not eliminates. The intent here is to eliminate it all together if possible.

Mini in their infinite wisdom chose to route the PCV ports directly through the cylinder head on the N18. They were also kind enough to place a check valve in the N18 Valve cover to prevent turbo boost from flowing back through these ports, pressurizing the crankcase where it would then vent through the front port back into the turbo. Unfortunately that check valve failed on my valve cover causing the turbo to overspeed at high boost. This BTW is what resulted in my turbo failing early.

Here's a few shots of the valve cover ports that duct air through the head and a picture of the failed internal valve.






So lets get on with it shall we. Step one remove your intake manifold and valve cover. This would be where you don't want to drop things or have metal shavings end up.



Step two: Locate the 4 ports on the back of the cylinder head.
This is one of the corner ports.



And here are the two center ports.



Here is a picture of the center ports with a .250 dowl inserted. Note the limited clearance between the dowl and bolt indicated. These bolts will need to be removed in order for the tap to clear.



Only work on one port at a time and verify the intakes valves are closed before proceeding. You will also need to block the ports with a shop rag as you will be using cutting fluid later as well as a solvent (iso alcohol) to remove the cutting fluid residue. I recommend Tap-Magic cutting fluid as they make one specifically for aluminum.

You'll also need to tape off the area you are working in to prevent any metal shavings from falling into the cam galley. (Falls under the heading of "Things not to do today!")



Once ready its time to tap the holes so that we can insert 1/4" diameter coarse threaded stainless steel plugs 3/8" in length. These are available at Homedepot for just a couple of bucks. Notice that there is insufficient room for a conventional tap handle. You'll have to use a 7/32" box end wrench to turn the tap. Remember what I said about breaking a tap off in the head. This would be the most likely place for it to occur. Take your time and go slow. I'd recommend taping each hole in three steps a little at a time. Removing the tap, chase the threads, a little more cutting fluid, lather, rinse, repeat.




Once tapped, remove the residual cutting fluid with solvent and insert the plugs with high temp RTV and an allen key. Here is the center ports and corner ports when complete.





Clean everything up, re-install the valve cover with a new gasket and an oil catch can which is now fully functional on an N18. You could also vent to atmosphere but I was feeling kinda tree huggy and put in a BSH can.


It didn't want to fit in the normal location due to the DDMWorks RIS intake. So a bit of hokery pokery later and it's in it's new home. After three days the soot that used to accumulate within a day on my exhaust tips is no where to be found. We'll see what the valves looks like in 10K miles.

Happy Motoring

 

I have heard that vent to atmosphere is not a good option because the pcv requires negative pressure to ensure it functions under boost. Someone said VTA could damage some engine seals or something by causing high crankcase pressure.

 

Wow, you are bold. Nicely done! Please post long term results, I will be following this with great interest.

 

@Tigger, you seem to have some good insight into mechanical engineering principles. Do you have any idea if there is any possible diy preventative fix for the vacuum pump failures that have happened on the N14 and N18. I have talked to dealer mechanics who have seen stock cars with good oil levels have vacuum pumps lock up and destroy entire engines. Any idea if there is anything we can do?

 

 

I'm slightly confused. I get the catch can.. but that pressure.. its still going into the (cam cover) head.. which is now blocked.. so you have zero venting of the pressure in the crank case?

 

I with you on this one, I don't get it.

 

Hi guys. Sorry if I wasn't too clear. Having had the valve cover off it was easy to see the way the system works and I should have explained it better.

There are two primary check valves in the N18 valve cover. The first one that failed on mine prevents boost pressure from pressurizing the crank case and venting through the front port. The second which is shown below prevents excess vacuum in the intake from over scavenging the crack case. There's also a small check valve in the front PCV vent that prevent excess inlet pressure from entering the valve cover but that ones of little interest.









The crank case always vents to the front port unless there is negative pressure at the cylinder head inlets. When not in boost the amount of vacuum there will always be much higher than through the front port. That's why catch cans on N18's catch very little. I'll see if I have a clearer picture of the underside of the valve cover. If so you'll see the primary PCV inlet to the system is right in the middle of the valve cover, then branches to both ports.

 

An interesting thing I have noticed about the N18 from watching my boost gauge and datalogging is that the pressure at the intake manifold is almost always at 0 (atmospheric pressure). Positive pressure only when accelerating and the ecu is trying to hit the load target. Negative pressure only when the engine is cold and the variable valve lift system is not used, once the engine warms up a bit the variable valve lift takes over and the throttle plate opens. When this happens it is obvious on the boost gauge, all of a sudden it snaps from -15 to 0. When the engine is warm, at constant rpm or small throttle changes boost is basically 0.

So I think that means there is only significant vacuum at the pcv passages into the intake ports when the engine is cold, so very little oil should get pulled through. Still, I like the idea of plugging them.

 

Correct. Most analog and OBD gauges will display the numbers you mention. However, the devil is always in the details. Keep in mind that vacuum is relative to the distance from the intake valve. Our cars have two relevant sensors, the MAP sensor in the boost tube and the temp/pressure sensor in the intake manifold. The PCV ports are 4 inches from the intake valve and angled to the inlet path which further increases local vacuum by the venturi effect.

I've attached two photos from the data logger that show the vacuum at a constant 40 mph and at idle with the car in neutral, foot off the brake. They indicate -.725 to -.870 psi under no load conditions. This translates to 20 to 24 inches of vacuum on a manometer. To give you an idea this is approximately 1/4 the vacuum generated by a typical vacuum cleaner or shop vac.

 

Yep, I get similar numbers, though I didn't realize it meant that much "suck". Looking forward to seeing the results when you empty your can for the first time.

 

What app is that? (iPhone?)

 

Spot on. It's Dashcommand on an iPhone. Besides the dashboard screen it has a separate screen called data grid. On that screen you can pick whichever PID to display that you want. Timing, AFR, fuel rail pressure, etc. There are a few it will not display without buying additional sensors and hardware which will plug into the Kiwi II wifi adapter. Specifically oil temp and pressure. Just about everything else from exhaust temp to voltages to what gear your in is available to view and record.

 

Good information, that's quite a task.

 

No need for a different gasket as the ports between the intake path and the PCV system is now blocked with 1/4" x 3/8" SS plugs that are tightened firmly in place with a thin coat of high temp black RTV. I'm very certain 200 psi of inlet pressure would not dislodge them. So there's only one place for the crank case pressure to escape and that's the front port.

If the system didn't allow this, the crankcase would over pressurize and dislodge the oil dip stick blowing oil all over the place. It's safe to assume that after 30 or so power runs to log data, a weeks worth of driving and an hour on the dyno, that the system is working as outlined. Although I think I made a error in theorizing the small check valve in the front port was to prevent ram air from pressurizing the valve cover. I believe the purpose of that valve is in fact to prevent air being pulled thru the valve cover and entering the intake tract drown stream of the throttle valve. If this occurred my guess is it would lead to an erratic idle as the DME tried to compensate between what the primary O2 sensor is telling it and what the throttle position sensor is telling it.

Ill look up the torques tomorrow but I highly recommend anyone considering working on their vehicle to pick up the Bentley manual. It is absolutely loaded with a wealth of information about our cars. Considering what information you get it's actually very reasonably priced.

 

100% agree, the Bentley is a very good deal, that information is well worth it.

 

Sorry for the long delay. Got sidetracked. The torque on both is 10NM or 7.3ft.lbs. The torque sequence for the valve cover is the center 2 bolts between the spark plugs, then up the RH side, up the LH side, across the back then across the front. I snugged them down a bit, twice by hand, then once to 5NM, followed by 10NM, and once more around to 10NM again. Ensure your mating surfaces are clean and dry and use a thin coat of RTV on the half moon shaped area on the LH side. The gasket is prone to leaking there.

 

One of our enterprising brothers here on NAM already solved that one by removing the mechanical pump and installing an electric one.
https://www.northamericanmotoring.co...mp-delete.html

 

I've got to admire your self confidence and ***** You have a theory about how things work and come up with a solution to improve things. The solution requires you tap something into your cylinder head Then when you have done this, you realise your assumptions and theory were not actually totally 100% correct, but you call this an "error"

Thanks for trailblazing on this, and potentially sacrificing your head. Hopefully it all works great, and then we can all follow. Keep us posted

 

No problem + many thanks! Tigger.
Won't get to it this upcoming weekend, hopefully the next, and by then I should have the Bentley on-hand.

 

It's officially been one week and about 400 miles since completing this mod so I thought I'd see what was lurking in the OCC. The customary engineering term for this assorted mixture of vaporized oil, toulene and other solvent condensates, and unburnt hydrocarbons is schmutz. A little over 20 CC's worth. The temperatures have been in the usual 80's for Florida so very little water. In fact its appears to be a fairly homogeneous mixture of the above.



On a side note Tigger has never been one to use any appreciable amount of oil between changes (approx every 5k) so I'll be keeping an eye on that as well since some people noticed an increase in oil consumption after blocking the aft port on the N14's.

 

Nice work, keep the lurking schmutz at bay!

 

This ships today from ECS.

 

Sweet. You should find all the N18 information relevant to the Countryman.

 

Do you know if the round diaphram valve (that failed for you) is a separate replacable part? I called a vendor and they didn't think so...