Updated, see below.

I love my mini, but it's having some big problems. Here's my current predicament and story. Two weeks ago I was commuting into work, driving up a long steep hill at highway speeds with cruise control on. Half way up the hill something catastrophic happened in the motor and without any warning. There was an instant loss of power, check engine lights flashing, along with horrendous knocking and vibration. It was really bad. I limped over the hill and pulled over. I checked all fluid levels and everything was in normal operating range.

Thankfully it's a CPO car. I've never been more thankful to have an extended warranty than with this car. I had the car towed to Herb Chambers in Boston. They didn't have any immediate answers, but within a few days discovered that it was a broken exhaust valve.



While I've encountered many car problems in my days. Never had I heard of or seen a broken exhaust valve. They tore appart the entire head, replaced the valve and re-lapped all the other valves.

I voiced concerns about where the missing chunk of valve went. The tech said that it "just burn up" which I found hard to believe. I requested that they send me pictures of the exhaust turbine wheel on the turbo to ensure that the fins weren't mangled. To my surprise they looked alright. They put the motor back together and gave me the car back. In talking with the service advisor, he estimated without the CPO warranty it would have been easily $4k worth of work. He also said that broken exhaust valves are not a common issue but they do see them from time to time.

When I got the car back it seemed like it had ~90% percent of the power that it had before. Since I'm planning on selling the car I wasn't going to push the dealer on something subjective like that.

I drove the car around town the next day with no issues. Two days after I was on my commute, and going up the same long steep hill. I went to pass a car with sport on and got limited power. A few seconds later the engine gave out again. Same instant loss of power and horrendous vibrations / knocking. Call Herb chambers and they said to try to limp the car back to them. I start the car, and there's a loud pop followed by smoke billowing from the hood. Checking under the hood the valve cover gaskets had burst out the front of the motor. Mini calls a tow truck and tows the car back.

At this point I either want Mini to buy the car off me or replace the entire motor. The tech I spoke with after bringing the car back suspects that I could have a failed piston which would warrant a new engine so my fingers are crossed. I suspect that the broken exhaust valve is a symptom of a larger yet to be discovered problem. We'll see what they come back with this time.

Here's my questions:

• What are possible causes of a broken exhaust valve?
• Any have similar experiences / problems?
• Has anyone had Mini buy a car back on warranty based on catastrophic issues with high milage?
• What negotiating tips and ticks have people used when dealing with warranty claims?

It is worth noting that the service department at Herb Chambers epitomizes high quality customer service. Everyone down to the guys moving cars around the lot is incredibly outgoing, respectful and most of all helpful.

Update:
The most recent issue was caused by a piston failure. Somehow the piston in cylinder 4 developed a monstrous hole in it along the edge. Check it out:



I'm not sure exactly how this occurs, I've been very diligent about all the maintenance since I've owned the car. If anyone has a similar failure or has insight as to how this happens I'd love to know.

Fortunately Mini NA held up their end of the deal and replaced the entire engine under warranty. The car is back on the road and almost out of the break in period on the new motor.

 

Wrong answer. They get sucked up the intake and travel from cylinder to cylinder causing damage. During idle when the intake valve opens there is some back-flow into the intake system. The chunk can get sucked into the intake.

It is not a common problem but a known problem.

 

The exhaust valve in your engine has overheated and lost a chunk of metal, causing the cylinder to lose compression.

Anything that interferes with valve cooling or creates extra heat in the valve or head can lead to premature valve failure. A buildup of deposits on the valve face and seat can have an insulating effect that slows cooling and makes the valve run hot. So too can poor contact between the valve and seat if the seat is too narrow, nonconcentric or off-square. If deposits build up in one spot or flake off in another, it can allow leaks that create hot spots on the valve as seen in your picture.

So IMO there are other issues that caused this to happen.

 

Did your engine run hot? Because cooling problems in the engine itself can lead to valve sticking and burning if the operating temperature gets too high. Low coolant, a defective thermostat, a weak water pump, a radiator obstruction, a defective cooling fan or fan switch, etc. can all make an engine run hot. This, in turn, makes the valve stems swell which may cause them to gall or stick in their guides if there is not enough clearance. If the valve sticks open, it can burn or be destroyed if it smacks the piston.
Blockages caused by casting flash inside the head or a head gasket that does not have the correct coolant holes can allow hot spots to form that can cause valve and guide problems. So too can a buildup of scale inside the head the interferes with good heat transfer.
Valves can also run hot because of elevated combustion temperatures. Factors such as retarded ignition timing, lean fuel mixtures (often due to leaks), detonation (from too much compression or low octane fuel) or preignition (from hot spots caused by deposits in the combustion chamber or too hot a spark plug) can all play a role here.

 

Our '08 S had SEVERE carbon buildup - it was breaking off in chunks and some got caught in the intake valve seats on #2. The spark plug was destroyed and the valves were bent. 111K. $4k later, it runs fine

 

That chunk of missing valve almost certainly didn't break off and disappear all in one massive chunk. More likely what happens is that a hot spot forms on the valve, which slowly over some time melts away bit by bit, until eventually the valve fails to seal properly. That causes zero compression in the cylinder, which causes the sudden loss of power.

I have had exactly the same thing on my R56 JCW on a couple of occasions. However, that is a race car, so runs very hard at prolonged high boost and high revs etc, so it is not entirely unexpected.

Out of interest was it cylinder 1? That is usually the case.

I am surprised that they didn't put all new valves in all cylinders whilst they had the head off, as the valves only cost a couple of bucks each.

The first time it happened on my car there was a some associated damaged to the head where the valve seats which needed repairing.

If this is a warranty job you really should be looking at a new engine now, or at the very least a new head

 

Thanks for all the great info on these failures guys.

Not that I'm aware of. No CELs or dash lights came on prior to the incidents. It's a shame that Mini doesn't put temperature gauges in these cars. The dealer changed the thermostat at 72k and there's a line item on the receipt for coolant so I imagine they replaced it then. The car has always seen 93 octane fuel.

The car got the walnut carbon cleaning at 49k. When they took the head appart most recently they said the intake valves looked really clean so it's unlikely that excessive carbon build up on the intake valves is to blame.

Nope, cylinder 2.

The service advisor tried to have all new valves put in, but Mini NA wouldn't spring for it.

 

bump for a new motor!

 

Are you driving your MINI with a new motor, that lost piece you asked about probably holed that piston.

Are you good yet or still waiting on your MINI?

 

Hot = Lean / Lean = Hot = burnt exhaust valves.


Money is on a lean condition... Due to carbon... HPFP failure/injector failure/carbon blockage.

That chunk missing from the piston is either also due to the lean condition or the chunk-o-valve breaking off the top of the position crown.

The tech should have seen the piston damage the 1st time they had the head off to fix the original valve issue.

If the piston damage happened later either it was a nick from the valve chunk - that grew due to the still-lean condition... Which points to the injector or carbon buildup on the intake valve..

 

My wife's '09 Clubman S with 71,000 miles is at Inskip with a broken valve. They are pulling the head to further examine. They say, because we are such good customers, they will meet us halfway on the cost. It is absurd that a car with such low mileage can have a problem like this. MINI should pay in full.

My '04 MCS had "piston/valve issues" resulting in increased crankcase pressure which continuously blew out oil pan gasket. Expensive fix. With 173,000 on it I couldn't complain... sadly had to trade it in for '12 MCS Hardtop. Miss my Supercharger...

 

That cylinder was running lean(fuel starved, maybe HPFP issue). No if, ands or buts about it. That piston head was melted and you can see as the indentations are smooth. The exhaust valve piece did not cause the damage to that piston. It sounds like that cyl was slowly melting from leaner AFR's thus dwindling the compression ring(top most ring) and crown, the exhaust valve can't take hot hot hot heat for very long so it chipped. they fix the valve but guess what, you still have low compression in that cyl so you're not gunna have all the power. The exhaust valve piece probably got injested through the system and blown out very quickly, doesn't typically cause a lot of damage on the way out.

what sucks is, in order to replace the valve the cyl head needs to come off, the fact that they didn't see that piston the way it was or correlate the two is mind boggling. this should be basic engine operation diagnosis to a mechanic.


I blew a 1" long piece of crown in my turbo subaru once, it destroyed the spark plug and got taken through the system, thankfully the turbine was fine. I leaned out in that cyl, needless to say i dropped forged pistons in and beat the **** out of it some more. I've seen, in person, a lot of turbo engine failures and yours is certainly not uncommon for an issue with fuel delivery. leaning out air fuel ratios will cause way too much heat for an engine to handle. it's only a matter of time till something goes, whether it's the piston compression ring or the exh valves. prolonged exh valve high heat exposure will certainly burn them(chip).

 

this looks like the same thing i found in a car i bought from the auction. the only difference is that the spark plug broke off and damaged the cylinder wall and piston. i will take it to a machine shop to hone it. hopefully it wont be alot of money.

 

Resurrecting an old thread here, but I have the same scenario... but it's not even an S model. 70,000-mile 2013 Clubman, broken exhaust valve on cylinder #2. What did you end up paying? I have a $3400 estimate, and they're only proposing replacing the two exhaust valves on that cylinder... which strikes me as dumb.

 

Ex valves are $15 a pop at www.rmeuropean.com, a head gasket and bolts, timing chain kit, water pump and pipe, and oil filter housing gasket will not be more than $350 in parts. Labor another 1k at most! Find another shop.

 

Obviously the valves can be had for cheaper, as you point out. I also found TRW valves for $20 each.

 

over priced!

source you parts from other vendors and you'll save at least 50%. even if the is the case, almost 2600 for labor! I think I need to change my profession lol

where are you located anyway?

 

Ha! I'm in L.A. This is a Mini specialist. Obviously we didn't go to a dealer, but it's hard to find reputable places for these things.

They've been dicking around for two weeks and I'm already out a bunch of money on a rental car. I could've bought a beater for less than rental by now. So piecemealing all the parts from different sources and waiting for them to be shipped... in the end it'd probably be a wash. Then again, if I'm going to order valves, I might as well.

Do you think replacing the additional 6 exhaust valves should involve much extra labor at all?

 

Doing the other 6 is additional work and time but it'll be systematic.

I would look for mini enthusiast in the area thru Facebook

The list has dealer prices so the shop isn't liable for anything wrong! Not sure why they have valve guids vs valve stem seals!