Posted this over in the W211 section but upon suggestion from another member I have now posted here; forgive me for double posting elsewhere.

I bought my 2007 E63 in June this year and absolutely LOVE it. It's in incredible condition, been an ex-wedding car and in superb condition.

However...today driving on the highway and overtaking I noticed some mild hesitation throughout the revs. Didn't think much of it as it was so slight that I thought maybe my mind was playing tricks.
A little later I was just cruising along and suddenly the car was surging and felt like it was misfiring. It had a lack of power and was reluctant to accelerate. At this point I looked in my rear view mirror and saw CLOUDS OF SMOKE (blue oil smoke) billowing out behind the car out of my tailpipes. I instantly looked at the dash and saw a yellow engine light (the one behind where the clock is). I then quickly cycled through my computer display and saw the oil temp was 135 degrees celsius!!! (275F). The hesitation/misfiring/surging/lack of power as well as the smoke was still continuing at this point, so I slowed right down and pulled over where it somewhat shuddered to a slow and rough idle, with smoke still billowing out. I honestly thought that is it, the engine is toast and I have blown one of the piston rings.

Trouble was, I was miles from anywhere in the middle of the NT (if anyone knows Australia, this is not a good place to break down) with no phone reception. I thought perhaps I can limp it to a nearby town (Adelaide River) and then call for a tow truck there.
I got out, checked the oil level - it was down a bit so threw in a little over 1L and got it back up to the max F mark. I checked under the car for any leaks - none at all. Engine filler cap looked fine as did the dipstick, albeit with a burning smell - no froth or milkiness indicating any coolant/head gasket issues - and the coolant temps were still rock solid normal.

I got back in it, started it up - it shuddered to a start, the dashlights dimming as it turned over - and with clouds of smoke, and no check engine light or warning messages at all. In any other situation I would've stopped, but if I'd left the car there, it probably would be days before anyone could come out and pick it up - and who knows if it would have even been still there in one piece.

Started driving it, and the smoke continued as did the shuddering/misfiring/lack of power when I pulled away, however it rapidly improved. I sat it at 95km/h, as that way the engine oil temp stayed around 129-130 degrees and no more - if I sped up faster (i.e. 130km/h) they climbed, so I sat it at 95km/h and kept the engine oil temp at 129-130 and stable. No more smoke (that I could see) and the misfiring/lack of power seemed to have improved a lot (note: I was afraid to put the foot down and test it out - I drove it very gently - however it was very smooth as always sitting on cruise).

I made it the 120kms into Darwin, and got it into a carpark. The drive in to the city I had some traffic lights where I was stopped and pulling away - no smoke, no real power issues that I could feel however I was driving it VERY gently. Once parked up in Darwin I checked the oil - the level was great and it hadn't used any since I topped it up. Had it idling and stood at the exhaust - no smoke. Got in and gave it some big revs - revved very cleanly and no smoke. Kept turning it on and off and it was starting well and turning over well as the engine fired up each time.

I have since started it up and taken it for very short drives after letting it sit for a few hours; it lets out a large cloud of smoke upon startup, that dissipates quickly. It drives completely normally...besides the cloud on startup, and the oil temps running high (120-ish) even at very sedate, low-speed driving. Engine oil level is good (after the 1L I put in before) and coolant levels and temps are still perfect; zero sludge or any milkiness in the coolant whatsoever.

So....have I done something catastrophic to this engine??

Or is it something such as a crankcase breather valve self-destructing or something to that effect, explaining all the sudden oil being burned off out the exhaust and the misfiring...which has now dramatically improved to being practically normal again?
I have had engines go on me before, and once they go...they tend to stay that way. Hence why I am perplexed as to how it genuinely seemed completely terminal...and yet now seems to be normal again (except for the cloud on start up and the very high oil temps - that is unchanged).

Any ideas?

 

The first thing I would do is pull the plugs and then start taking the intake manifold off and cleaning the oil in it.

What cylinders were misfiring? If its 3 and 4 its probably from oil build up because those are the closest to the pcv valve and the most oil would be in that area in the manifold.

The only thing I font like is the oil temp hitting 275. I beat the living crap out of my car and never saw over 245.

I would clean intake and put new plugs and fresh oil and go from there.

After you are up and running and if it runs good run s few cans of gas treatment because all your cylinders are probably black right now.

 

Definitely sounds PCV related. Run the codes.

 

The normal water temp with high oil temp is a mystery though...

 

It is due for new oil in 500kms...I am thinking that perhaps with all the ageing oil that got dumped into the combustion chambers that it heated it right up and potentially cooked the oil, breaking it down. Hence the high temps?

I started the car this morning after sitting all night. Started immediately and zero smoke! That's a good sign...

Took it for a short drive and then sat it idling for 20 mins and the oil temp reached 102C before shutting it off. FYI, ambient temp here today is 36C. For all intents and purposes, it seems to be fine.

Not taking any chances though, and it's getting towed to the mechanic tomorrow.

 

Will be asking the mechanic to do exactly that first thing.

Are PCVs known to fail suddenly like this?

 

Thanks for the tips, mate. Guessing the misfiring came from the plugs being smothered in oil!!! They are new plugs so I'm hoping they can clean up OK. Definitely time for a new intake filter and a manifold clean; the car has done 128000kms and this is now a good excuse to do it.

Would you recommend an engine flush too?

 

I would buy 2 cans of bg44k and run them back to back. here is a thread with my results with it,

https://mbworld.org/forums/c63-amg-w...my-engine.html

 

Well, $3400 later and the car is back, all in good order. Engine is fine, oil level is perfect now and not using any. Compression is fine. And the PCV valve inspected and apparently that is fine too (I thought it could have ruptured leading to the oil burning off in the engine). Its nice to have the car back.

Turns out the radiator had four small holes on the side that had water coming out like a sprinkler...and straight into the air intake. The mechanic believes that the smoke and misfiring was from the water vaporising in the engine and out the exhaust. I disagree as it was definitely oil smoke and that can be confirmed by the burnt oil and the drop in oil level. However the mechanic believes it would have given codes if it had oil through the motor like I suspect.

I can't really explain how oil went into the engine, except that it may have something to do with the engine going into limp mode when the oil temp hit 135C right at that moment - I was doing 130km/h on the highway and going into limp mode obviously cut fuel and retarded timing etc causing the misfiring which then in turn potentially led to perhaps oil venting back from the crankcase - however that is just an assumption. It definitely "gulped" down some oil at that point, and it doesn't seem to indicate any real reason or lasting damage (thank god) that can explain it.

 

Should have inspected the engine oil filter for metal. I've seen part of the piston ring land break off causing oil burning but top of piston is fine allowing proper compression at low load.