Both the top and bottom of my n14 are bone dry. Exhaust is dry too but its consuming oil at 1 quart per fill up. No visible smoke, CEL or performance issues.

 

Intake manifold? I think that's where mine is going.
How many miles, how old is your PCV valve?

 

That is a lot of oil in so few miles. If it is not Dripping out of your engine, which it appears not to be from your pictures, then it is somehow going through your engine. In my mind, this leaves a few option: 1) burning in the combustion chambers due to poor ring seals - normally at that usage you would expect to see some smoke, 2) through your intake and into your valves - you may have black caked up valves and intakes at this point, 3) burning up through your turbo... then partially back into your intake again... then through your catalytic converter, slowly destroying it and appearing clean at the tail pipe. This is what I think at least. If it is under warranty, take it in for service. If not, no need to ever change the oil again, just replace oil as it is burned and replace the filter every 5K

 

One quart of oil per fill up is say 1 quart of oil per 8 or 9 gallons of gasoline? 32 ounces divided by 8 gallons is 4 ounces of oil per gallon of gasoline. 4-cycle engine combustion is more complete than 2-cycle combustion so while 4 ounces of oil per gallon of gas would have a 2-stroke motorcycle engine smoking a bit your MINI engine might not smoke.

Or it smokes but you just don't see it.

For help in seeing smoke arrange to drive the car away from a low sun, either a rising sun or a setting sun and check in the rear view mirror as you give the engine varying amounts of throttle or you back off the throttle.The low sun can really make any thing in the exhaust quite visible.

With a turbo charged engine the turbo can lose oil via a seal. If the seal is on the exhaust turbine side the oil leaks into the hot exhaust. In this case the oil would not burn completely and you would likely see smoke.

If the turbo leaks oil on the compressor side the oil is introduced into the intake air and the oil then goes through the combustion chambers where it might get consumed enough to not smoke or smoke very little.

No experience with MINI -- thankfully my JCW engine turbo appears to be holding up well (with just 20K miles it had better!) -- but with my Porsche 996 Turbo I don't recall the Porsche techs I talked to voicing any concern about oil leaking out the turbine seal but they did say oil leaking out the intake seal was not unknown. It was not uncommon for a bit of oil to be in the intake in the air cooled inter coolers. The techs were only concerned if the inter coolers were "full" of oil. These were at the lowest point of the intake system and if one or both turbos were leaking oil to any degree the inter cooler would collect it.

Thankfully my 996 Turbo turbos never leaked even at over 160K miles. Might add the owners manual called for a 2 minute idle time after "hard" use before shutting off the engine to give time for the turbos to cool down some. While the engine was idling the idle exhaust gases were cool compared to what they were when the engine was working hard. The turbos were only exhaust and oil cooled, too. At any rate I followed the owners manual. And I let my JCW engine idle too for a minute or two before I shut if off if I have been pushing the engine any.

Another place oil may get into the engine is via the crankcase ventilation system. These can be quite inefficient/ineffective in removing oil vapor from the crankcase fumes as they are routed to the intake. Might add these engines -- DOHC configuration -- are notorious for creating a lot of oil vapor. I've seen a video of an OHC engine (dual or single I can't recall) in which the camshaft cover was clear. At some point as the RPMs got higher the area under the camshaft cover was just filled with oil vapor, whipped into vapor by the rapidly spinning cam (or cams).

An engine that smokes upon cold start can be from oil vapor making it through the air oil separator all the way into the intake. Generally the hose from the crankcase connects to a fitting that is perpendicular to the intake manifold. Crankcase fumes "rush" out of this connector and the heavier oil vapor particles can't make the sharp 90 degree turn. The oil vapor hits the opposite wall of the intake manifold and there returns to liquid form. As the engine continues to run the oil is pulled down into the chambers and burned.

If the engine is shut off with some "fresh" oil on the intake walls this will drain down and collect on top of the closed intake valves or even flow into the combustion chamber if the intake valves are open. Upon cold engine start there can be some brief period of smoking.

Again falling back to my experience with my Porsche cars the Porsche techs told me it was quite common to when the intake manifold was "opened up", the throttle body removed which then exposed the intake manifold exposed to the fumes from the crankcase, to find some of the intake walls wet with oil.

It was my "theory" that engines that consumed heavy amounts of oil with no leak sign and no smoking - except at cold start -- were engines that had received a subpar air oil separator. An engine that is losing oil via rings or valve stem seals or excessive valve stem/guide wear -- but not enough to make a racket -- is a smoker almost all the time. It will leave a cloud of smoke behind the car when the car takes off from a stop. It will continue to emit some visible smoke while cruising down the road.

Unless your car's engine is doing the smoking almost all the time my money is on either a leaking turbo seal or more likely a faulty/inefficient air oil separator.

If you are so inclined you can check the engine intake system downstream of the turbo but upstream of where the hose from the crankcase ventilation system connects. If you find oil in this section of the intake then a turbo seal is suspect, If this section is "dry" then check downstream of the throttle body where the hose from the crankcase ventilation system connects. You will probably then find it "wet" with oil.

If neither areas have any real signs of oil then the oil would appear to be leaving via the turbo and a leaking turbine seal.

 

So I bought one of those straight pipes for a turbo muffler delete. So when working on that I will be on the turbo piping. So if I pull the bottom hose of the turbo before the intercooler, I would expect to see a lot of oil there if the turbo was leaking? In the Mini, oil from the valve cover would also likely show up there.

 

I have an oil catch can, so it can't be entering the intake manifold I believe. I have no catalytic converter so I should see oil at the tail pipe. Unless this rate of consumption is too slow to show smoke / oil.

 

The inter cooler should be downstream of the turbo (its compressor). A leaking compressor side seal will have oil in the intake system from the compressor on down.

I believe the valve cover vent hose connects to the intake *after* the turbo and after the inter cooler, certainly after the MAF (or whatever the engine management system uses to measure the mass of air the engine is consuming) and after the throttle valve (if present) to avoid fouling these with any oil that might come from the valve cover hose.

If the intake shows oil sign from the turbo on this may mask oil that is entering the intake via the hose from the valve cover. If the intake is "dry" from the turbo on and then if there is substantial sign of oil in the intake at and downstream of where the valve cover hose connects to intake this is a good sign the oil is entering the engine from the valve cover.

 

Maybe take a video of the tailpipe during start up and while reving it, and/or consider having someone take a video from behind you while accel / decelerating. Smoke during hard acceleration i think would be exhaust valves and hard deceleration would be intake valves.... someone can correct me on this if i am wrong.

 

I have an N18 and from what I can see, the valve cover dumps into the air intake hose after the air filter and MAS right at the turbo (about 1 inch before). Turbo compresses the intake and push air down through to the bottom of the inter-cooler, air is cooled through inter-cooler and then goes up and over into the intake near the firewall side of the engine. The turbo will be hot but the job of the inter-cooler is to cool the air charge so I can't see how oil does not condense back out to a liquid and collect in the inter-cooler. So, it would appear to me looking at this design the inter-cooler on my Mini S it is a gigantic oil-catch can. Since the turbo is getting a constant oil bath, that might be a benefit except where the oil coats the blades unevenly.

I've heard the N18 engine doesn't have as much of a problem with the intake getting clogged so I can see in the design why this would be the case but I believe the performance of the inter-cooler would continue to degrade over time. I think my plan is to eventually remove it and clean it and I expect to find oil in there. I will really be surprised if I do not.

 

If you describe the layout correctly and I have no reason to doubt you that's to me rather surprising that the crankcase vent hose connects to the intake that "early" in the intake air stream. With my 996 Turbo Porsche, even with my supercharged Hellcat, the intake can run below atmospheric pressure even when moving briskly down the road. I have not bothered to data log/data monitor my JCW but I expect it behaves similarly.

The Hellcat supercharger sits on top of the intercooler which is nestled down between the banks of the engine. So the intake above the intake to the supercharger runs with no pressure.

The Turbo IIRC has the crankcase hose connected to the the intake at some point just after the throttle body but the turbos are suprisingly tame in that one can drive the car and under normal operation the turbos do not make boost. The engine intake is exposed to low pressure all the time until of course the turbos make boost.

Any oil in the intake will not contribute one iota to the turbo's lubrication needs. The air flow and the oil vapor flow will be drawn to the compressor scroll and its blades. I doubt the back of this will even have any oil on it.

Even when not producing boost the compressor turns at some ungodly RPMs. And when generating boost the compressor turns at around 100K RPMs IIRC -- and any oil that manages to get on the scroll blades at lower speeds will not stay on the scroll.

Unless the amount of oil being introduced to the intake is "huge" (as might be the case with a leaking turbo seal) the inter cooler is "self cleaning". The violence and speed at which air travels through when the engine is working at max or even at part throttle will carry along any oil or water (that can also be in the fumes vented from the crankcase to the intake) and keep the inter cooler relatively clean.

 

I did a search on the forum after posting and I found people cleaning their inter-coolers.
Here are some more links that say people found oil exactly like I said and that disagree with your post. If oil cools back down and forms a liquid and has to go up hill 3-4 feet, I don't see why you think it will turn back from oil coating the inside of the rubber back into a mist.
https://www.mini2.com/threads/clean-...cooler.157996/

 

I pulled the pipe between the turbo and the intercooler, it is SLIGHTLY oily there but I think this is common on many turbo cars.

I might be losing a bit of oil here but this doesn't seem like "a quart per fill-up" rate of loss. There were no obvious patches or pools or oil, just very slightly oily to the touch.

 

This is good to know.

However, from everything I've read it wouldn't be on the side of the Turbo to the Intercooler. At that point the oil is still under temperature. It just came out of the valve cover, it just went through the turbo which is connected to the manifold (hotter than the valves), it just got compressed which is "work" and causes the contents to heat. You need to check on the "other side" after going through the intercooler, there the gas is cooled. So at that point, you would be talking condensation and turning it back to liquid oil. It would collect in the intercooler but for the most part be blown out of there because of the pressure. However, on the other side you have an expansion spot--another large pipe. There is where you increase the chance for condensation. Also, that pipe goes straight back up. So I would check there instead.

 

Every turbocharged car will collect some oil in the intercooler,no way no how otherwise. PCV dumps the vapors into the turbo intakes to be re-circulated. If PCV fumes are fairly oily for whatever reason (which will happen anyhow after a while), guess where that oil is...

 

My car is using a 1/2 quart per 500 miles, not a cup of oil every 1000 miles. That oil has to be going somewhere...

 

Keep us posted if you find a solution - our 2007 R56 N12 has been burning oil close to that rate. New VC gasket, new coils/boots, new, new, new everything the past 2 years. Just replaced the PCV membrane in the valve cover yesterday, replacing the PCV hose when it arrives.

I normally keep the oil filled right to the top nib - I may start filling it to 3/4 up between the nibs - who knows, my particular R56 may be overfilled at the top nib. I'm going to schedule a leakdown and compression test in the next couple of weeks. I just hope the cylinders haven't worn to ovals. IDK how the previous owner drove her.

 

Did the PCV membrane make any difference. That is what I was going to do.

 

Just installed the PCV membrane yesterday, will see if it eases the oil burning as I drive her this week - have only put about 15 miles on her since the new membrane - will put results in this thread.

Noticeable improvement in the idle and acceleration response already, though - should steadily get even better. Also installing new PCV pipe as soon as it's delivered.

No smoke ever - no leaks ever. As you say, the damned oil is going somewhere.

 

Are you running 10w-30? I probably will go with 10w-40 next oil change. I've read a couple of threads saying this makes a difference and probably better if you are in a warm climate. I'm in Texas.

Let me know if you see a difference. I have the new PCV membrane and I was going to do it in the next oil change but I think I should do it tomorrow.

 

Been using Mobile1 5W-30 full synthetic since we got her in 2016. I live on the coast of S.C.; hot and humid in the summers. Haven't seen a difference in oil usage corresponding to seasonal temps - let me know if the oil grade change helps. Membrane replacement easy, just be careful taking that plastic cover off - if you haven't seen it, here's Mr. Grumpy's writeup on the replacement:

https://www.northamericanmotoring.co...-question.html

 

Yeah, I was originally thinking of waiting because I wanted to clean the top after removing the spring. I was worried I might get solvent in there and it would be better to change the oil afterwards.

 

I ended up doing my PCV. It had one area where it was probably leaking a tiny bit but I do not believe that was the issue. Also, it looks to me like the area on top of the engine from the PCV diagram to the PCV pipe is basically a gigantic oil catch can of sorts that acts more like a coking catch can.

 

A few things from what I've read so far:

You can't compare an N12 engine with a N14 engine, the N14 engine is turbocharged and the N12 engine is not, they have different PCV systems and the N14 is direct injected and the N12 is port injected, Apples and oranges.

The turbochargers on second generation MINI's don't have oil seals, they rely on a very close tolerance bearing, you can easily check this bearing by taking the rubber hose off of the turbocharger compressor inlet, grab the center of the compressor wheel and try to move it axially and radially, there should be no play and it should spin easily.

There are two one way valves in the N14 head cover, the one on the back of the cover prevents boost pressure from the throttle body from pressurizing the crankcase, the other allows crankcase gasses to vent to the turbocharger inlet when the engine is under boost. In normal operation, when the intake manifold is under vacuum, crankcase gasses are vented to the throttle body, and are vented to the turbocharger inlet when under boost.

If the one way valve to the turbocharger fails closed and boost pressure is allowed into the crankcase, it will cause oil leaks all over the engine. If it fails open, every time your engine is in boost, it will blow oil in through the turbocharger compressor.

The PCV valves are integral with the head cover. I think that you need a new head cover.

 

Not on an N18. I have a N18. The PCV is a membrane and I just replaced mine without putting on a new cover. I haven't found a 2nd hose yet going directly to the throttle body as you indicate for the N14. On the N18, it looks like the PCV membrane will vent excessive crankcase pressure through the PCV membrane (as soon as the pressure exceeds the spring) through the back of the valve cover (mine is pretty dirty back there is my guess by the way the PCV membrane looked), through the PCV hose into the inlet right at the lip of the turbo. Oil in a mist form like enters turbo, put under pressure travels down to inter cooler, goes through inter cooler is cooled back to oil, cakes inside of intercooler and bottom of charge hose. What remains in mist travels up charge hose into intake manifold. So the reason the N18 is less like to cake the intake is because it will cake the back of the valve cover, the inter cooler, and the bottom of the charge hose. I'm sure some oil also cakes the turbo blades but since this under quite a bit of heat most of it likely burns off there.

So sometime in the future, I will pull the valve cover off and clean the back of the valve cover between the PCV membrane and the PCV hose. I'm sure it is a mess back there with caked on oil, sludge, and dry oil grease. It probably won't change engine performance much but it will allow a fresh place to collect up new coked oil so it stays there and doesn't travel further. Once that area gets full (and clogs), then no matter the condition of the PCV membrane, you will create back pressure and cause the leaks all over the engine that you reference.

The back of the valve cover on an N18 looks to me to be an Oil Coking Catch Can built into the engine because it is a thermal cold spot. I do worry a tiny mine is full and could be starting to block the pressure and if I don't get on it soon could cause oil leaks.

 

I only addressed the N14 head covers. They changed the head on the N18 engines, it has internal ports in the cylinder head to vent crankcase gasses into the intake ports, eliminating the PCV line to the throttle body, you can't compare N18 heads and head covers with N14 heads and covers. One advantage of the N18 head is that it greatly reduced carbon build up on the exhaust valves.