Long story short I had some new tools on my hand and wanted to do some testing on my MINI (2010 Clubman S, R55, 110k miles, I've had it since 93k). In the past I've had cylinder misfire codes but they went away. I've also had a coolant leak I can't pinpoint – no visible leaks. A little smoky exhaust (but not blue smoke). I was worried about a head gasket leak.

First thing I used a head gasket leak tester kit (check for gasses from combustion chamber escaping into the coolant system). Seemed OK as the solution did not turn yellow:



Then, I had myself a compression kit lying around and wanted to make use of it, so next thing I checked each cylinder. (left to right looking straight at the engine, 1-4). I checked each cylinder dry and then with a few drops of oil inside (wet):

Cylinder 1: 152 dry / 156 wet
Cylinder 2: 140 dry / 151 wet
Cylinder 3: 160 dry / 175 wet
Cylinder 4: 160 dry / 175 wet


So basically I am ranging from 140 to 160 dry – is this acceptable or do I need to investigate further with a leak down test?



Well , back to the thread title – how bad are my spark plugs? Here are the photos below (I don't know if they've ever been changed). Is there any indication of carbon buildup here (I've read with DI fuel system this is more of a problem) or is it simply corroded plugs?








Much thanks for your help

 

That is a lot of oil on the plugs which could definitely cause misfire problems. It looks to me that the valve cover plug seals are probably leaking .

 

I'd say the plugs are just well-worn. I'd replace them with the correct grade for your car. (Personally, I use the inexpensive copper plugs & change them at every oil change at 7,500 miles).
Does it use much oil? At that mileage, you might consider changing to a 5W40 oil
The compression readings seem largely OK. I'm guessing the car is used mainly for short runs, so I'd use the highest grade of gas available (yes, I know $$$) & a can of injector cleaner once in a while won't hurt. Maybe repeat the compression test in a month or two.

 

Looks like you need to replace the cam cover gasket - that is WAY too much oil on those plugs. There shouldn’t be ANY oil on the spark plugs.

 

@njaremka @MVPeters @DenisMcG thanks guys appreciate the feedback. I'm just trying to put a plan together so I can do as much as possible at once.

- replace spark plugs
- replace ignition coils or no? I noticed two of mine look different than the other two (can see in the photo above)
- replace valve cover gasket (is the gasket alone sufficient or should I replace the whole valve cover with it? Also I've read conflicting opinions on whether or not to use ultra grey permatex on the gasket for the best seal)
- replace PCV valve cover? (I read this is a common problem and would be a good time to replace if replacing valve cover)


I think I'm also going to pick up the walnut blasting kit from FCPEuro. I have two high mileage MINIs in the family so I think it'll be worth it.

 

I would go for plugs, coils, and valve cover with gasket. The PCV is integral to the valve cover, so no need to purchase separately.

 

Just put in my FCP Euro order.. wallet taking a smoke break right now.

However have a good amount of stuff to do all in one day so should be productive – will update the thread in the next couple weeks when I get a chance to do everything.
- new plugs
- new coils
- new valve cover w/ gasket and PCV valve (I cheaped out and bought this on ebay because it the price difference was just huge). Can I reuse the existing bolts for this? If so can I just re-add threadlocker like peramatex blue
- walnut blast kit (going to use this on both MINIs, high miles. Should pay for itself in one use)
- Zimmerman rear rotors and Akebono pads

A little off topic but have any of you used Akebono pads? Multiple sites that sell them I saw they don't come with retaining clips - are they not needed, or do I just reuse whatever is there? I'm also replacing the caliper bolts because BMW says "renew bolts" in the ISTA procedure (even if not changing caliper). $6 per bolt, yikes

 

You should be fine reusing the cam cover bolts. I can't see why they would need to be replaced. Make sure the seals are replaced.

I have reused the caliper bolts, too. Again, I can't see why they would need to be replaced for a simple pad change.

Finally, I have used Akebono pads, and find they very well suited to a daily driver Mini. They stop well enough, and have MUCH less dust than the OEM pads.

 

The clips are only needed if the clips are worn or grooved. You will apply a little grease to slider portion of the clips (some brake pads include the paste). I have our Bav Auto coils and doing fine, my OEM delphi ones kicked the bucket on my way to work out of the garage. They tend to need replaced more often then standard packs. Geuine ones seem to do this also. I believe they just cant handle the heat cycles, that's where their are so many revisions of the older part.

 

Follow up - haven't done the walnut blast yet (all parts arriving for next weekend), but did have a chance to get the cheap borescope out and look inside the cylinders.

Here's what I found:


Cylinder 1



Cylinder 2



Cylinder 3



Cylinder 4


It seems like there's carbon build-up but it doesn't seem horrible. I'm curious to see the intake valves once I get around to taking the intake manifold off.

Has anyone done a "piston soak" to clean the deposits shown above? I'm curious as to the correct procedure for it – in terms of what position to crank the cylinders to


Also, cylinder 2 looked different to me. I know the photo quality is pretty bad so it's hard to tell, but wondering if there's anything obvious to someone else as to why C2 has the lowest compression.

 

That looks like either coolant or oil in cylinder 2. Run a small hose in and try to suck the liquid out so you can see what it is.

 

Thanks @DenisMcG . It could be leftover oil when I did the wet compression test - but strange that seems like theres so much in there when I did the same to all the others. will post another photo when I get a chance

 

Yeah, cylinder 2 look likes it’s drowning, but #3 looks like it’s at the top of the bore. Cylinder 2 might just be too close to the camera.

 

Ok, not sure how I missed this but I definitely have a head gasket leak. I did the head gasket test with blue liquid over the coolant tank, and it didn't turn yellow - but somehow I missed this!


oil and coolant mixing on inner rim of crankcase

notice glob of milky white on left side of the valve cover. Makes me think leak is on the left side

inside throttle body, same milky wide substance on the outside of the throttle plate

inside oil cap


The coolant leak is not huge, so hopefully I can seal it up with a head gasket sealer. I want to try the K-Seal product which doesn't have sodium silicate.



Anyway I already took the intake manifold off already (getting the wiring harnesses all off is a little bit of a pain). I'm going to go ahead with the walnut blasting on the intake valves. I'll also clean up the intake manifold - will post pictures of them – there's a LOT of carbon

 

I also have a lot of oil leaking around the throttle body. The wires around there are covered in gunk. It rained recently so the pictures might show some water - but you can see the oil here:





video:


Obviously I'm dealing with several issues but wanted to know if there's anything I should go ahead and replace now that I already have the intake manifold off, and am getting the valve cover off as well. What about the turbo - is there any way to easily check for coking or clear those lines?


Thanks

 

On the turbo lines they usually dont get coking. Its most of the time before the intake/ PCV, and valve cover. Oil will build up on the intercooler, you can pop it off and clean it out. I checked my main lines on the intake and it had a little oil but they dont seem to collect.