Hi Folks,
I have an '08 MCSm with 55,000 miles, and I'm experiencing what I think is engine knock, but I'm not sure. Only on hot days, usually uphill, I'll get a ticking sound that's mild at low rpm and mid throttle, but at higher revs and full throttle, it'll be a loud ticking accompanied by a cloud of smoke out the exhaust and a momentary lapse in power. That's what my wife filmed here:
Is this engine knock? Could it be something else? I'm using 91 Octane Shell gas, and don't get any CEL.

 

I saw a blue cloud of smoke coming out of the tail pipe, not a good thing! If you're hearing knocking with blue smoke...

I also heard multiple pinging.

 

Sounds more like knocking, but there is more going on.
It's too late to start running 93+ octane and expect an improvement, but it wont hurt.

Have you inspected/cleaned carbon deposits off your intake valves?
How do your spark plugs look (I assume they are original)?
Do all 4 look the same across 4 cylinders?
Any sign of spark arching on the coils (you will be pulling them out to inspect the plugs)?

If it's not the fire (coil, plugs) and not the fuel (go 93 and re-test) and not the air (unlikely), then it must be issues with the combustion chamber. Those are the most expensive kind of issues...

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Take it in for a carbon cleaning & a diagnosis from a shop that knows these cars. Continuing to drive with spark knock will kill your engine.

 

I have reason to believe that you're knocking is the result of burning oil causing your octane level to plummet, in your video I'm hearing multiple knocks followed by blue smoke out the tailpipe. The question is how the oil is getting into your engines combustion chambers, valves seals and piston rings come to mind. You need a leakdown test in all cylinders!

 

Thanks for the suggestions, guys.
I ordered new spark plugs and the special socket yesterday, so I will pull the plugs and take a look soon.
My boss also thinks it's burning oil, which would account for the smoke and knocking. I do have to add a lot of oil, about 1/2 a quart every 3rd fill-up or so.
I don't think any stations near me carry 93 octane - it's usually 87, 89, or 91/92.
My mechanic is out sick this week, but I'll be visiting him early next week to get it checked out.

 

I have found that stop and go city driving eats up more oil than freeway driving, I have monitored long trips to my brothers house and found I lose a lot less oil on the freeway. Look at it like this, your engine is constantly receiving fresh clean oil from time to time. Add to this a walnut blasting every 30k-50k miles and things are that bad.

 

My 09 MCSa has the exact same problem as the one in the video and the symtoms are the same, the only difference is mine is a 40k car and I got a bigger cloud of smoke. :(

 

With these Mini Coopers miles doesn't seem to make much difference, you can have problems early on in its lifetime. I doubt many have gone 80k without problems far and few.

 

made an appointment with the dealer for next week, they said i can still drive it, but dont push it too hard.

 

Sadly if your experience is anything like mine it is the beginning of the end. Mini started out that way and kept getting worse. The dealer always said nothing was wrong. Once it was out of warranty they acknowledged a problem and speculated anything from carbon on the valves to block inclusions. After an ineffective cleaning of the valves I pulled the plugs and discovered the electrodes in the #3 cylinder were completely gone (not sure how Mini missed this one). When I took it back to the dealer they told me they were not entirely sure what went wrong but that I needed a new engine(Approx $9000). I have since stopped going to the dealer and now go to a local Mini only shop who also tells me that I need an engine but is at least able to tell me a plausible reason. According to him the steel between the ring grooves is too thin (according to Mahle) and will break and allow oil into the cylinders causing misfires and ultimately the plug problem I am seeing. Anyway the car still "runs" but I pump a lot of oil through it and give it a new #3 plug every couple of thousand miles. At the end of the day the whole engine needs to come out and I am not yet ready to spend $6000 (mini only shop).
Sorry for the bad news. On the plus side when I need a smoke screen I can lay down a cloud that would make James Bond proud

Sincerely,
John

 

Hvnt fix mine yet, but i hope the cpo warranty will do its job to protect my wallet......

 

Here is a video of mine knocking. We had an AFR meter in and it was 13.9:1, knock hit right at 16PSI of boost. Mine only knocks maybe once a week, I usually can't reproduce it after. Smoke was black and not at all white/blue. After this thread and the other knocking one I will check my spark plugs...

 

Last weekend my boss helped me do a leakdown test. All 4 cylinders were reading ~0%, so it's definitely not a piston ring issue.

I replaced the spark plugs with the same model of NGK Iridium plugs. here's a picture of two of the old plugs next to one of the new:

The one lowest in the pic has darkened threads, but other than that everything looks fine. One plug had a tiny bit of black soot on the electrode but that was easily blown off. My boss said they look like it's running lean.

I've noticed a bit of knocking since then, but I've modified my driving habits to spend less time at low revs/high load, and this seems to have helped a lot.

At some point I think I'll pull the intercooler to check for oil buildup, and maybe take a look at the intake valves. Question: If the valves are covered in carbon, would this be a cause of knocking? How exactly?

 

At what rpm are you getting knocking?

It would be only part of the problem, carbon on the intake valves, intake runners and in the combustion chambers. It's most likely carbon buildup in the combustion chambers, intake valves, intake runners. This carbon when hot will cause pre-ignition igniting the gas before the spark plug fires which is the knock you hear, also carbon is great at absorbing fuel like a sponge.

My suggestion is you're do for a walnut blasting of the intake runners, valves and a few bottles of BG 44K. The BG 44K is the most effective way to clean your combustion chambers short of removing the head to blast the carbon away. My engine used to knock/pre-ignition even when it was cold outside, after 5 bottles of BG 44K it only knock/pre-ignition when temps are 88+ degrees with a dry heat. A few more bottles should do the trick, my pistons aren't all black anymore, they're starting to look like silver aluminum color. When using the BG 44K you need to drive for quite awhile, otherwise stop and go traffic won't clean up your cylinders as much as driving for prolong periods of time.

 

generally between 2,000 and 3,500 RPM.
I haven't been driving the car lately as I'm working on a plasti-dip mod, but if it's still a problem next week I'll look into the walnut shell blasting.

 

That's where my Mini knocks, 2500-3500 RPM. Well the knocking is caused by excess heat in the combustion chambers, carbon deposits after a while get HOT igniting the gas before the spark plug fires. I would recommend the carbon blasting and a few bottles of BG 44K, I'm going to be using BG 44K in every other gas tank this summer. Since our tanks are only 13.2 gallons you can use half of the bottle of BG 44K, so one can used for two tanks. You can find BG 44K on eBay or your local BG service center.

 

Mine was back finally, compression test results was quite low. They pull the head and all cylinders were scored.

 

Most instances of piston & cylinder scoring can be traced to lack of oil, use of improper oil fuel mixture, foreign particles in cylinder, or excessive carbon build-up in the cylinders. What were you compression readings?

So if an N14 had readings of 155 psi across all cylinders would you assume that your engine is free from cylinder scoring?

 

I'm not too sure, but the dealer tells me that normal should be in the 170s, but mine was doing 120-150, and the secret menu in the tach (14.00) might be able to store the fault code?!?! I use to have 2 codes, no CEL. But it use to burn the top 1/3 of the dipstick in 2 days, mpg struggle to get above 27 with 70% freeway trips.

 

My oil burns at a very linear rate, more of a gradual from the top of the dipstick measuring points, 170 seems a little bit high for a turbocharged engine. No one I'm aware of has measured even close to that, highest I have seen is the 160's. My high compression Datsun 2.0 liter was 180 brand new, my Toyota 1.6 liter was also 180, given these are naturally aspirated engines. The base coopers I know are 180 for normal compression.

 

My car has gotten somewhat better with the new spark plugs and revised driving habits, but I've noticed one thing that's concerning since getting a Bluetooth OBD2 reader to monitor engine stats: The coolant temperature is ~225°F. This seems really high to me - it's above the boiling point of water! My wife's Prius runs at ~190°F.
Is this normal for our engines?
I've noticed that if I run the interior fan at full blast, the coolant temp will drop to ~180°F, and this does help with the knocking.

 

These temperatures are normal. And yes by running the AC at MAX it will lower the coolant temp.

 

Yes, it is above the boiling point. But, it's a closed system under pressure. From what I've read, those temps are normal..

 

Okay, here's another question about knocking: Aren't these cars supposed to have a knock sensor that retards the timing? I remember reading about that on my mom's '94 Volvo that took premium. I figured by now that would just be standard equipment on all cars. I accidentally filled up with 87 octane last week, and now the car knocks every time I drive home. It's imossible to drive in a manner that avoids it entirely. Surely something must be wrong? Could my knock sensor be failing?