2nd Gen JCW Positive Crank Case Ventilation

Are you still staring at your engine......???

The "S" has a somewhat unique PCV system. it's controlled by a set of valves inside the plastic valve cover. There is a built in system of traps, a maze and a cyclone separator that try to separate and condense the oil back into the crankcase. This system in the valve cover is not serviceable. There are also a couple of pressure control valves that open and close based on vacuum or turbo pressure...... basically if it's under load or not.
At idle and slightly above when the system is under engine vacuum the flow is out the PCV at the firewall. When the system goes from vacuum to pressure the flow is out the front hose going to the cold inlet side of the turbo. Only one path direction is operating at a time, not both.
They both end up delivering fumes to the intake side of the engine through the intake manifold. The second path goes through the turbo and unfortunately also can end up coating the inside of the inter cooler chamber with oil film residue.

All of the flow direction originates at the valve cover and end up at the intake manifold leading into the head past the intake valves.... leaving a little carbon presence as they are drawn into the combustion chamber.

There ya go....

 

In other words, the PCV line passes distal to the valve cover, over the large intestine and proximal to the valves, thus depositing carbon build up. This can be avoided by taking Clarvisan, so you don't notice it.

Jim

 

What'd he say? :crazy:

 

Good man Jason, now drop and give me 10.

Jim

 

The yellow disc in the photo is the valve cover air/oil separator. When this stops doing its job, case pressure builds enough to force oil past the valve cover gaskets.

 

Is this the same cyclone separator set up in the 2nd gen. Cooper?
A friend is having her valve cover replaced because her Cooper started using a lot of oil.
It was so bad it fouled a plug.
Maybe it will need a treatment of that stuff (Seafoam) to DE-carbonize the intake valves.

 

Seafoam will probably not decarbonize the intake valves. If there's much carbon build-up, blasting with walnut shells is the only real answer.

 

Bummer, that would require head removal. Maybe some gas additive.

 

No, walnut shell blasting is done with the head in place. The dealer has a tool for just that purpose.

Dave

 

Is it an S or JCW (thus DI, probably has carbon buildup on the intake valves, never mind the fouled spark plug you mentioned above) or is it "just a" Cooper, which uses port injection and shouldn't have any carbon issues?

 

It is "just a" Cooper. Good news for my friend!

 

Carbon buildup can still happen on the intake valves, but it's enormously less likely since they're washed by the injected fuel. The DI engines get the gunk from the PCV system, but nothing to wash it off the valves. That's why they coke up over time.

 

Tell your friend to run a bottle of Chevron Techron through it before each oil change. Cheap cleaning that will help keep the carbon at bay.

 

Will do.

 

This is not true for the direct injected N14/N18 engines. The fuel additives may clean the combustion chamber a bit, but will not combat carbon buildup on the back of the intake valves and in the intake ports. This is all because of the nature of direct fuel injection.