First time posting, but just curious about others experiences.

Have had my 07 Cooper S for 4 years now, driven over 50k miles with not a single issue until 2 weeks ago.

I was driving and felt the car "slip" and the check engine light started flashing and I lost about all power when pressing the gas pedal.

Also, on idle the car sounded like the engine was about to fall out.

Took it to the shop and they found that an exhaust valve had broken due to carbon build up (see image). This repair was not cheap by any means and I would like to prevent this in the future.

Any advice on dealing with carbon build up? Is this a common issue with these engines? What is recommend to help prevent this from occurring again?

I have already fixed the car and it is running great now, I am just looking for ways to prevent this repair again.

 

Many threads on Walnut Shell blasting, etc. Try searching on that for quick info.

 

Typically carbon build up is an issue on intake valves, not exhaust valves. This is a little on the odd side...

 

I agree with the above, carbon buildup is not much an issue on the exhaust valves, but on the intake valves. Is the timing chain intact? Did it jump time?

Not to mention there isn't much carbon buildup at all on that valve.

 

I try to get my valves cleaned every 25k-30k miles. I don't shortchange my services by doing it at 50k. I've seen my valves after 20k miles and it ain't pretty, that's even with a catch can..

 

That valve looks like one of mine did after a cylinder ate the sparkplug electrode in my R53.

 

Maybe it was the intake valves that had carbon build up. But the exhaust valve is what broke. It looks like it melted honestly.

The repair tech told me he was surprised the engine ran at all with the amount of build up inside. They went ahead and cleaned the engine while they were doing the re-build so hopefully I do not have to deal with this for a while.

The tech said to clean them every 50k miles, but I probably will head your advice and clean then every 20k.

Is this problem related to this particular engine?

I have owned a BMW, Mazda, and an Audi in my life and this is the first I am hearing about walnut blasting an engine.

 

We have customers that will Seafoam their cars every other oil change to circumvent the buildup caused with the DI engines, but you will at some point in the cars life need a proper carbon removal done.

 

Direct injection is the cause, nothing but pcv gasses ever hit the back of intakes (if I understand the concept correctly)
CRC makes a DI spray although I cannot find it locally yet. Not sure how effective it is, but worth a try ???

 

N14 and I know of the BMW N54/55 as being a culprit of this as well.

At 20k miles, I would suggest taking a look at the valves. If you don't think they look too bad, then carry on until 30-35k, but for me, this is in the stable probably forever, so I'm maintaining it as best I can.

 

I use this somewhat regularly in just gas tank, can you explain this line off the site ?
" Let it soak for about 5 minuets while you remove the adapter and make sure your boost clamp is tight and back to factory look"
what adapter ? not mentioned anywhere else in article

 

On the N14 engines you will remove the PCV hose from the back of the valve cover, and pour Seafoam into the hose until the engine starts to stumble/choke, but not get too over zealous as to create a hydrolock situation, it's a balancing act.

Many times a second person is needed to apply a small amount of pedal response to keep the car running while administering the Seafoam treatment.

But once about half of the can has been ingested by the engine, shut it off, and let it sit for about 15 minutes. Once you start it it will be hesitant to run, so you will have to help it for the first few seconds of operation, but once running keep the RPMs around 3,000 RPM until smoke subsides.

You will have stored misfire codes, as well as a SES light illuminated, so a scan tool of some sort will be required to finish the job.

If you have an N18 the same theory applies, except we sell a bottle of Seafoam with a nozzle on it which you will clamp into the upper charge pipe prior to the throttle body. N18 Seafoam Treatment

Just pouring the treatment into the fuel tank is a fairly extinct fix for fuel system issues as of late. Modern fuel systems are more resilient, as well as fuel quality tolerances have been raised. Lubricity additives are always going to be endorsed, as higher lubricity will increase pump & injector life, but the fuel system cleaners have lost their "potency" since the GM fuel system issues in the late 90's to the early 2000's.

 

thank you for the in depth description, so the adapter mentioned is just the pcv hose?

 

The adapter provided with the N18 kit is to pinch between the mating sections of charge piping next to the passenger strut tower. You unscrew the clamp enough to get the nozzle in, clamp it back down, so as to not have a boost leak, and spray the contents into the intake tract.

The N14 kit is just a can that you will pour into the PCV hose that is removed from the back of the valve cover.

 

gotcha n14 here, so no adapter.... thanks again

 

No problem, glad we could help.

Let us know if there is anything we can do for you.

Nick
Detroit Tuned
586-792-6464

 

Here is a photo of my vales at 47k miles, look closer the there should be two vales there. Photo is from techs Snap On cam....The worst the dealer had ever seen. The tech went through 2 bags of walnut shells and was about to open a 3rd bag. I keep my car very clean and maintained and it was disgusting to see the pics. The car runs great now, but like you i want to avoid this from happening again and i'm not so sold on a catch can (several hundred dollar contraptions all the way down to a bud light can). The dealer advice....don't drive it so easy.

 

BTDT - welcome to the "broken N14 exhaust valve" club.
Membership criteria are not very exclusive, but are pretty expensive.

In my case, I had a sudden loss of power, CE light, and 3-cyclinder lumpy idle at 56K miles, right out of warranty.
After leak down tests, the exhaust valve on cyl 4 was identified as the culprit.
Zero help or goodwill from the dealer or MINI USA, so I ended up DIY-ing a new N14 engine swap as a (cheaper) solution, but doing a valve job on the old engine was also an option.

Sadly, this is a common problem on DI engines, as other stated, but N14s seam to be most susceptible to the exhaust valve failure.
Everyone is familiar with inspecting and walnut shell blasting the intake valves, but it's the exhaust valves that are a more expensive problem.

Running Seafoam may be part of the answer.
Walnut shell blasting intake valves clearly helps, but I will be applying the same treatment to exhaust valves as well.

YMMV,
a

 

I wish that there was a way to let all MINI owners know to plan on having the intake ports/valves cleaned every 25k. Even if you spend $400 at the dealer, the car runs so much better afterwards, it is a good thing.

Every month we get someone surprised that this is an issue. unfortunate....

Mike

 

 

Intake valves dont get hot like exhaust valves do... thats why carbon buildup on exhaust valves causes breakage; as the valve surface starts getting hot spots which weaken it until failure.

Oil catch cans, regular oil services and walnut blasting dont do much for carbon build-up in the combustion chamber, but they do help keep it to a minimum.

 

Of the few dozen engines I've torn down, not one had valves free of carbon deposits. Carbon deposits are normal. Carbon deposits in general do not make valves break.

Millions of engine have run billions of miles without breaking valves.

Mini uses cheap valves, that's why they break.