2009 R56 MCS 106,500miles
Oil changes 6-7k miles.

So Sat. I was cruising and got a CEL with audible dings. Realizing that this can't be good start to slow then feel it misfiring badly. Get off the interstate and its trying hard to stay running with hard stumbling. On visible inspection of the engine everything seems ok. So the wife picks me up and we go get computer and tools to see whats going on.

I hook up to BavarianTech and it tells me Cyl 1 and 3 have a misfire.



So start with pulling those plugs. Plug 1 seems ok. However plug 3 is covered in a hard oily substance and no way it was firing.





Shine a light into the plug hole and the top of the piston appears to have sludge on it as well. At first glance #1 piston seemed to be clean but it also has slight sludge on the top of the piston. Pulled 2 and 4 and they looked ok.

Hoping the timing chain or related parts hadn't failed I pulled the valve cover and the timing chain and guides still looked good.


So I thought if I could get some new plugs in it it could possible get it home. Napa had some Bosch plugs but they had the 6 point 5/8 head. I had a socket but realized the hard way it doesn't fit in the cylinder head so had to go home and grind it down. However I got new plugs in 1 and 3 and it still runs on only two cylinders at idle but will smooth out above 2500rpms. Still puts up a misfire on 1 and 3. Tried changing coil packs between 1 and 2 and same result.

So I got the trailer and took it back home.

So I was looking for advice on how to proceed next. Its been almost 2 years and 35k miles since it was last walnut blasted. The first one was at 71k and was bad. So I'm sure the valves are gunked up and was hoping to get rid of it before it needed it again.

1.) Could it be possible that they got so bad it was allowing all the buildup into the combustion chamber and snuffing combustion?

2.) Is it possible a cracked piston could lead to this oily spark plug? I've been adding more oil fairly regularly which I think is attributed to the valve cover needing to be replaced.

3.) Possible maybe the timing chain jumped a tooth and timing is now off? Not sure if one tooth would only throw off 2 cylinders or all 4. Haven't measured TC stretch yet.

4.) I can walnut blast the valves again, however doubt that will help the combustion chamber problem. Is pulling the head going to be the best option to take or will a seafoam/water treatment help clean it out? With those cylinders failing fire will that hinder a treatment?

Hoping to get a borescope to try to peak down in there and get a better idea whats going on. But wanted to see if anyone else has had a similar problem.
Thanks!

 

Sorry to hear about your troubles.

You seam to have covered the easy steps, so now it's time for a compression and leak down tests to evaluate if the exhaust valves and pistons/rings are OK.

Hopefully they are. However, in my case (similar symptoms on '08MCS with 56K miles at that time) an exhaust valves on cyl 4 was destroyed. I ended up replacing the entire engine with OEM replacement ($3.5K and a long story).

I do not believe the cabron caked intake valves would cause a misfire and permanent damage to the engine, so cleaning them (obviously needed) would only be required if the rest of the engine is OK.
Similarly, there must be serious slop in, and obvious damage to the timing chain, to fault for misfire on 2 cylinders.

Good luck,
a

 

A, Thanks for the reply. A compression and leak down will def. be next. I unfortunately have tools scattered between our place and a storage unit so wasn't thinking about that this weekend, just trying to get it home.

I have a borescope on the way and hopefully it will do a good job of peaking down the SP hole.

So with your thoughts on the timing chain causing a misfire. Obviously there is a foreign substance in at least one of the cylinder for sure, that would lead me to conclude that was the cause of the misfire then try to figure out where that substance was coming from. Maybe oil from crankcase getting past rings, oil from the intake due to bad PCV system, etc. This is all just hypothesizing and the tests will help rule each out, but until I can do that later this week just bouncing ideas around.

With your burnt valve why was the decision to go with a new engine vs some head work? If you have a link detailing the whole thing you can just reply with that as well and I can read it.

Minimal costs to get this thing drivable and somewhat reliable to get it sold is the plan. However I can't just band aid it to fail again in 1k miles just to sell it.

 

Here is some of the story:
https://www.northamericanmotoring.co...n-cyl-4-a.html

I have another thread somewhere detailing the DIY engine swap project. Another one working through the options and decision tree on doing engine swap vs. top-end rebuild.

It's hard to impossible to band-aid a non-running (no compression + misfire) engine.

If you have a place to work, DIY an N14 engine swap is a very straight forward proposition. It helps a lot if you have a garage and a spare car, so that you can take your time and work in relative warmth and comfort at your leisure. I only needed to buy an engine hoist and load leveler (~$150) to get it done, the rest were all the standard tools accumulated over 20+ years of wrenching on german cars.

Good luck,
alex

 

Thanks for the link. I'm reading through it now. But I did get a chance to work in on it today. Measured chain tension slack and got 69.55mm. So just over the 68mm but not to bad. I put my cams in the locking position, but didn't verify with the locking pin. Just estimated. And it seems they might be slightly off.

However. Compression numbers.
1- 152 psi
2- 152 psi
3- 0 psi
4- 150 psi.

So that explains and sounds similar to the info in the linked thread. I'm getting my leak down tester together and should have that diagnosis by the end of the week.

I also pulled the intake manifold as well. This was number 3. The worst one.


It'd be nice if it was just so gunked up it was getting closed. But that might just be wishful thinking. I do have another vehicle and plenty of tools. Been working on an E30 to replace the Mini with but it still isn't finished yet.

I think for me the decision to repair is greater. As the thermostat and water pump are new in the past year. Along with a new turbo oil feed and return line. Oil cooler gaskets as well. I did spot an oil leak while I was under it. I still think a lot comes from the valve cover as there is residue all over it around around the gaskets. I was planning on a new valve cover as I think that is causing a lot of my oil consumption problems. 1500-2k is more manageable when I'm looking to sell it within 6 months. I doubt I'll get the ROI back from a new engine when it comes time to sell. If it does bump it up enough then it might be worth looking into.

 

Your valves look like the worst case scenario I have ever seen!

Can't wait to see inside cylinder #3, it's not everyday you get to see what could happened to any of us. I wonder if the timing chain jumped a few teeth and cause a valve to collide with the piston.

What tool did you use to measure the timing chain slack?

 

Well. Had 100% leak down on #3.



1-80%
2-88%
3-0%
4-86%

Leak was coming out of the exhaust so pretty certain it's a cracked exhaust valve now. Will get the head off soon to get a look of how bad it is.

However. If the cams are going to be removed to get the valves out. Is it really necessary to lock them while removing the head? Reinstall sure. Guess maybe for removing the sprocket bolts it'd help?

 

I used one of these

http://www.kochtools.com/index.php?p=product&id=93

99% sure the exhaust valve broke due to excess carbon buildup.

 

Sadly this sounds almost identical to the problem I am having. Driving along and then all of a sudden car is idling really really rough. Misfire on cylinder 2 and 4. Pulled plugs and the plug for cylinder 2 looked almost identical to the one in your picture. Replaced the plugs and cleared the codes...misfire on cylinder 4 is gone but still have misfire on cylinder 2. Was gonna do a compression and leak down test here after I get over having a tooth removed today. I was kinda hoping for a bad injector as I just got the car walnut blasted back in August. And replaced the valve cover in September.

 

Well hell, I TOO am having a nearly identical problem. Misfires on #2 and #4. happened all of a sudden while driving down the highway. Doesn't seem to be fuel (unfortunately, I bought a new HPFP before I was able to check the fuel rail pressure, which was OK) or ignition related, but I could be wrong. Misfire didn't seem to follow any certain coils. My car is a 2007 MCS with around 135K miles. I was planning on rebuilding a 1969 MGB engine soon, maybe I will instead be doing a 2007 MINI :(

DRoc7822 and csmitty, could you do me a favor? Can you look at the wire harness that runs under the intake manifold. On the backside of the head on the right side (while looking at it, left side of the vehicle), just before it goes over the head and branches off further to the right and also to the coils. Can you check if there is wear on the armor and wires near where it passes by the air filter housing? I had wear here. I hope I caught it before anything bad happened, just kind of want to make sure that it isn't related. The area is in this picture, although I have thoroughly taped it and added convoluted tubing in the picture:

 

So, if we've got burnt exhaust valves, does one replace all of them, in case they too are compromised or just the ones that are obviously damaged? At $46 each, that works out to be a fairly expensive proposition, but still less than if another fails. Are they failing because they don't close all the way or are they just not very robust, so another is probably not far from going? Does anyone know a decent place to get a different brand of valve, that is hopefully stronger and/or cheaper? Anyone ordered custom ones? How much, if so?

 

If the other valves have carbon deposits around the edge then that would explain a burnt valve, this carbon on the outer edge is what heats up the valve and sooner or later it will weaken the valve. Another note is our Mini's run on the lean side so this is also cause for concern, to lean and your rings break. Add to that our operating temperature of 226F!

 

The valves themselves are decent quality valves, I believe that like the N18 the N14 uses sodium filled stems to help with heat removal.

IMO the problem lies in the lousy design of PCV system. The design causes excessive oil vapors to reenter the intake which decreases octane, cakes up the intake valves and increases in-cylinder temperatures resulting in super hot exhaust valves.

If you are there replacing one, I would go ahead and do the others. Also, inspect the other components like seals, etc.

 

That all sounds like what I was thinking as well. If you're in there, just do it right. I'm pretty positive that is my problem, but I haven't pulled the head yet. I've heard that the stock valves are sodium filled as well. They are just so expensive :( I might contact Ferrea and see how much custom ones are. I imagine more but it could be interesting to ask.

My car has 135K miles on it and is on the original clutch, so I'm thinking about replacing it while everything is torn apart...and then if I have the engine out and the head off, I don't see much point in not freshening up the bottom end and just be done with everything...

I am going to put a thermal barrier coating on the valves, combustion chambers and pistons (assuming I do the bottom end). This should really help with several problems, I believe. Does anyone have any experience with this? I have done my own with Tech Line coatings but I might send them off to Calico or Swain, still not sure. Doing them yourself is cheap but usually not as good, obviously.

 

I agree replacing them all would be the ideal solution. However I really just want to get this thing gone. So we'll see.

Has anyone removed the camshafts without the hold down tool?
http://www.kochtools.com/index.php?p=product&id=185

Hoping its just a nice to have vs a must have like the timing tools.

 

Just confirmed tonight that I do have a burnt exhaust valve. I was able to rotate the valve slightly and see the damaged area with an inspection camera. I'm in the process of removing the head now.

I contacted Calico Coatings and they said to coat the whole head (combustion chambers, intake and exhaust ports, valve faces and the backs of the valves) was only $70! That seemed crazy cheap to me but I called and they said it was right. So that is my plan, to send them the head and new valves.

CSMITTY, I don't really know what that tool would be for, unless it is to keep the cam in place while everything is still in the vehicle. I guess I will find out shortly

 

here is what burnt intake valves look like on a Mini...I had the exact same symptoms on my 2010 JCW while driving home from work on interstate, normal speed and then loss of power and CEL...these were from cylinder #2 and caused misfire on 2 and 3.

 

Howie... how were you able to get an inspection camera to see the damage? I have basic mechanical experience but have never messed around with anything internal wise.

 

DRoc7822, I just stuck it down the exhaust port. I had the intake and exhaust manifolds off already. Even with the camera, I could only see about half the valve. I can't really recommend this...but the way I rotated the valve was to turn the cam to lift it slightly off the seat, then I grabbed the retainer with a pliers and turned it. You don't want to put scratches in anything, so I tried to be as gentle as possible. I found which valve was bad by shining a light down the spark plug hole and looking for light in the port. My valve is pretty bad, so it was visible, lighting the area around the guide up.

 

@Peanut

I have done a lot of research on oil consumption and burnt valves, the number 1 reason we get burnt, broken valves is because of DI. There are tons of other cars that burn oil just to have it washed off the back of the valve by the injector. I'm going to get a walnut blast every 20K period, there's nothing more you can do.

 

How does walnut blasting the intake valves help with burnt exhaust valves?

I would think that burnt exhaust valves results from elevated combustion temperatures due to many reasons such as excessive oil coming from the PCV system and leak by from the turbo seal.

 

My post was meant for Peanut.

Peanut has two burnt intake valves because of all the massive carbon build-up on the intake valves. I'm sure the carbon absorbs heat and then eventually burns the valve making it structurally weak which is what we have here. I'm pretty sure all that carbon played a big roll in Peanut61 intake valves demise. Nobody is taking about burnt exhaust valves here even though the root cause is oil consumption and a poorly designed PCV system.

 

What about in my case then? Is it the same.... cause I believe I have a burnt exhaust valve and had gotten the car walnut blasted back in August. So if the valves going bad are because of carbon buildup... why did it wait about 7500 miles after getting walnut blasted to go bad?

 

I believe that everyone here but Peanut have been discussing burnt exhaust valves not intake valves.

 

I was responding to Peanut's post about his burnt intake valves, am I not allowed to do so?