MINI Cooper Forum banner
1 - 18 of 18 Posts

·
Registered
Joined
·
25 Posts
Discussion Starter · #1 ·
limp mode and then 3 cylinders with lots of blue smoke. Cylinder No.4 spark plug is oil fouled
I’ve just overhauled the cylinder head, now only 30 miles of running and this problem.
I’m fearing a blown piston with the amount of oil around.
is there a potential problem with the PCV dumping oil into cylinder No 4?
looking for possible faults before I strip it down
 

·
Registered
Joined
·
13,193 Posts
there is a weakness on gearbox end pistons on them its made worse by oil and running lean ,, i've had a few where the piston skirt was blown away ,, had one have a bent rod suspect the head gasket failed on it and let coolant jump across the gasket and lock the motor up this bent a rod and piston leant over in the bore ,, they eat oil if dont get rid of the shite bmw plastic oil rings
 

·
Registered
2005 R53, 2005 R53 lightweight, 2008 R55S, 2012 R58 FJCW, 2014 R60SD All4, 1996 Mini Cooper 35SE.
Joined
·
1,516 Posts

·
Registered
2005 R53, 2005 R53 lightweight, 2008 R55S, 2012 R58 FJCW, 2014 R60SD All4, 1996 Mini Cooper 35SE.
Joined
·
1,516 Posts
and quite possibly a re-sleeve, don't rush to buy pistons just yet

Tire Automotive tire Wheel Tread Synthetic rubber
 

·
Registered
Joined
·
13,193 Posts
lean out most common where the lack of fuel makes combustion process heat and pressures go through the roof, the only thing that controls the heat is adding fuel funny enough,, but if add to much will push it the other way and do the same thing,, AFR needs to be kept correct,, so if you add oil burning its a fuel can add to it, same as worn injector , leaking valve seat on exhaust side can also do same trick, failing turbo can add to it, air leaks pcv system leaks also, the coolant tempos can do the most damage the fastest as these engine already by design like all new tech engines run at 105c to 117c , then add worn water pump or fault thermo housing , even the aux water pump can also have effect to it,
i always on such engines replace the injector in that hole and after rebuild do a lot of live data and make sure its fueling right ,, also check AFR on rolling road but have access to ,, even a mot test on emissions will show if have issues still,
 

·
Registered
2005 R53, 2005 R53 lightweight, 2008 R55S, 2012 R58 FJCW, 2014 R60SD All4, 1996 Mini Cooper 35SE.
Joined
·
1,516 Posts
it's caused by oil consumption, and related deposits, carbon build up including injector tips, reduced fuel quality due to ingress of oil (maybe some using the wrong fuel to begin with not helping), and resultant pre-ignition/knock, worse at lower rpm in boost conditions, so these can let go suddenly during acceleration, it doesn't have to be only when pushed hard at all.

you'll see the injector nozzle, some of the holes might be blocked, the backs of the inlet valves will likely be coked up and probably oil soaked, and you will see deposits around the rings and ring lands, this can be an ignition spot and will effectively turn the inside of the engine into a type of plasma cutter in the blink of an eye, it's quite common on cars that have been mapped on top of a tired engine, you know, new owners changing the use of an ageing motor etc. They can take out a rod in the process too.

I've done a string of them, and have one in progress now, just the same except this wasn't a mapped one, older woman owner, same scenario otherwise, oily etc.

piston from the block above....

Gas Auto part Motor vehicle Automotive tire Automotive wheel system


the FJCW one here now....

Water Automotive tire Motor vehicle Fluid Tread


I put a forged temporary motor in this one as these sleeve repairs can take too long....

Gas Motor vehicle Wood Carmine Chair

Tire Land vehicle Vehicle Wheel Motor vehicle
 

·
Registered
Joined
·
25 Posts
Discussion Starter · #9 ·
I did a top end rebuild and replaced an exhaust valve. Inlet valves were badly coked up. After I put it all back together I did around 100 miles and the engine went onto limp mode then 3 cylinders.
Natural material Wood Gas Kitchen utensil Metal

I think the engine had been run for some time before I got into it.
This was No 2 cylinder, my current problem is cylinder 4
Could have been mapped at some time I suppose.
plugs are showing whitish to light brown
 

Attachments

·
Registered
Joined
·
13,193 Posts
white oil burning , pull the pre cat 02 sensor out and poke a light in see if cat has burnt away common just before they melt engine down,, if its decat car then part fo why its nailed , everyone i have done the rings go brittle ie can snap them with little finger compared to fueling right cars that just bend
 

·
Registered
Joined
·
25 Posts
Discussion Starter · #11 ·
it's caused by oil consumption, and related deposits, carbon build up including injector tips, reduced fuel quality due to ingress of oil (maybe some using the wrong fuel to begin with not helping), and resultant pre-ignition/knock, worse at lower rpm in boost conditions, so these can let go suddenly during acceleration, it doesn't have to be only when pushed hard at all.

you'll see the injector nozzle, some of the holes might be blocked, the backs of the inlet valves will likely be coked up and probably oil soaked, and you will see deposits around the rings and ring lands, this can be an ignition spot and will effectively turn the inside of the engine into a type of plasma cutter in the blink of an eye, it's quite common on cars that have been mapped on top of a tired engine, you know, new owners changing the use of an ageing motor etc. They can take out a rod in the process too.

I've done a string of them, and have one in progress now, just the same except this wasn't a mapped one, older woman owner, same scenario otherwise, oily etc.

piston from the block above....

View attachment 287690

the FJCW one here now....

View attachment 287691

I put a forged temporary motor in this one as these sleeve repairs can take too long....

View attachment 287692
View attachment 287693
Your comment re. Incorrect fuelling worries me. I filled up with E10 before I had these problems.
is E10 suitable for the Cooper S? Should I have used super unleaded (95ron)?
 

·
Registered
Joined
·
13,193 Posts
is this just a N14 problem ,thought the N18 was fixed and didnt coke the valves any more?
the n18 is same way gets same things happen like the n14 engines do , i know this as have refreshed many of them now and all have same issues with age and miles etc,
 

·
Registered
Mini Cooper, 2008, Manual
Joined
·
126 Posts
IMHO the reason PSA/BMW introduced the n16 and n18 engines was more to do with meeting Euro V emission regulations and PSA have gone on to make the Prince engine Euro 6.2 compliant for the remaining models that use it. If PSA/BMW continued to use the plastic oil control ring in the later generation engines then they had no intention of making the engines more reliable - no regulatory requirement. My broad observation is that the Gen 2 mini was designed as a throw away commodity - probably with a design life / MTBF of 6 years or 60,000 miles!
 

·
Registered
Joined
·
13,193 Posts
IMHO the reason PSA/BMW introduced the n16 and n18 engines was more to do with meeting Euro V emission regulations and PSA have gone on to make the Prince engine Euro 6.2 compliant for the remaining models that use it. If PSA/BMW continued to use the plastic oil control ring in the later generation engines then they had no intention of making the engines more reliable - no regulatory requirement. My broad observation is that the 2 mini was designed as a throw away commodity - probably with a design life / MTBF of 6 years or 60,000 miles!
totally agree with you on that, its a throw away car like many if not all car makers it would seem, with a excuse that its government emissions laws that kit them off and not their p,ss poor designs that rob people, just wait untill euro 7 comes on car makers are already looking at it with so much will need to be done to meet it that it takes away from the battery tech cars, the prince engine won loads of awards on emissions to power etc , down side when something is made so cheap and complicated things dont seem to last I would guess ,, makes me laugh when people put cheater tubes on wide band 02 sensors rather than have the ecu programmed to work correctly then wonder why mpg and melt downs happen ,, where prince engines were designed in a way that bmw/psa spent millions to run fueling trims at a base line more to the lean side by also running very hot, heat in petrol engines causes lean running
 
  • Like
Reactions: dazdwnsth

·
Registered
Joined
·
13 Posts
limp mode and then 3 cylinders with lots of blue smoke. Cylinder No.4 spark plug is oil fouled
I’ve just overhauled the cylinder head, now only 30 miles of running and this problem.
I’m fearing a blown piston with the amount of oil around.
is there a potential problem with the PCV dumping oil into cylinder No 4?
looking for possible faults before I strip it down
Have you done a compression and leak down test? Sounds like a blown head gasket? Was it run with low oil? Do u hear a gurgling noise when u shut off mini?
 
1 - 18 of 18 Posts
Top