simandang

My friend was behind me tonight and noticed my car was smoking a lot when driving in manual mode aggressively. It was 75 degrees and the car was properly warmed up. He said the smoke was black/grayish.

Only mods car car has the secondary cat and resonator delete. The car is a 2013 and warranty just ended.

The car car was at two dealerships before the warranty ending at 49k and everything was in good shape. They did replace a leaking transmission pan and did the full transmission service.

Should i I be concerned? My friends also have C63s and were really concerned.

Usually white smoke is coolant right ? So black should be oil at high RPM should be some blow by which for a big motor is a normal?

MTV10

White smoke means coolant.... Check your coolant level.

Ludedude

Yep. Check it and also check the oil for coolant (foamy, chocolate milk looking, nasty) and the coolant for oil as well. Coolant burning off is usually a sign of a head gasket (best case) or something else amiss. You should also do a compression and leak down test as well for more clues.

hachiroku

at times it can take A WHILE of driving to burn off any residual moisture in your exhaust. i wouldn't jump to conclusions until you've witnessed the smoke after your car has been driven steady state for 45min-1hr.

til then, monitor your coolant and oil levels.

Savage-wp

Keep an eye on your coolant. White smoke is water vapour.
Yours is a 2013, so you shouldn't have the headbolts issue.

Alex.currie44

The underlying assumption is that being a 2013 you should not have head gasket issues but water in the cylinders = head gasket leak. Oil that looks like coffee with cream = head gasket as it had oil in it.
Contrary to one opinion it can happen at low temps. It does not take more than a few minutes to clear the steam on start up which is totally different that white smoke.
I would suggest that at 75F you would not even see initial steam condensation

jptaylor

I agree, any residual moisture/condensation in the system burns off before the cold start idle even drops back down...if you had been doing some spirited driving for quite some time then you should have had no white smoke under heavy acceleration(and white smoke is NOT water, it is antifreeze, water turns to steam not smoke)...under those circumstances it would be relatively commonplace to see maybe a little blue or black smoke when you get on it hard as all engines have some amount of blowby...if you did indeed have white smoke from exhaust then it IS coolant and there is only one way to introduce coolant into your exhaust and that is through your combustion chamber, meaning that it entered your head, meaning that you have a compromise in that sealing system somewhere...could it be a head gasket? most definitely, but it could also come from a few other places. Head bolt for example..not saying that you have the god awful m156 head bolt failure issue but you could have a head bolt that has loosened over time(these thing DO happen) and coolant is wicking up the threads and past the bolt head and only presents itself when there is high coolant system pressure....

....and as for the compression test i would actually hold off on that until i knew more about the issue...as in i would first do a cooling system pressure test as a base line, if the cooling system is tight as a drum then you can rest a little easier as the head gaskets ARE PART OF THE COOLANT SEALING SYSTEM....dont panic just yet, be smart and do or have some exploratory diagnostic work done so youll either ease your mind that everything is good or potentially find and fix an issue before it becomes catastrophic.


...also, after the engine has been running longer that 10min after a cold start(enough time to burn off any condensation in the system), shut the engine down and remove the oil fill cap...look at the underside of the fill cap, should just be dark fluid colored. If it looks like chocolate milk on the bottom of the cap you may want to have someone start digging sooner than later

Alex.currie44

For the record, your antifreeze while primarily ethylene glycol,does have water in it along additives to prevent corrosion of the cooling system to control ph and neutralize the various acids formed when EG oxidizes which need the water to go into solution. Chemically, the steam you refer to is 2 parts Hydrogen and 1 part Oxygen which of course we know is H20 - water!

As to your head bolt theory it still comes down to the head gasket failure letting steam into the cylinder,

jptaylor

ok, I'll play along,

Under no, zip, nada, ZERO circumstances can water ever be smoke, EVER!!!!! If you have smoke coming from the exhaust it is a fluid OTHER than water burning off.

...and as to the back to the head gasket issue, just because you have coolant in the oil does not mean 100% that you have head gasket failure. coolant can enter the oiling system in several ways other than past a breached head gasket.

Alex.currie44

You ever seen a head gasket blow my friend? When it goes the rapid expansion of the aqueos phase is quite astounding and of course when EG burns it gives off smoke. I get your point re it being more steam than "smoke" but it sure looks like it and to some degree it is smoke as the EG burns.
You will have to explain to me how coolant gets into the oil other than a crack in the head or the block.

jptaylor

the threads on our head bolts protrude into the coolant passages, so like i said, if the head bolt loosened coolant could come up the threads , underneath the bolt head and out into the head where it mixes with oil and is returned to the pan.

...and yes, i have seen multiple head gaskets blow, but a head gasket blowing is an immediate and catastrophic mechanical condition which will an m156 to a screeching halt which is NOT what the OP said happened....he just had a little white smoke visible from behind while giving it the beans.

and as far as whether or not my statement about coolant getting into the system via the head bolt threads is just a theory, I just had to replace my headbolts because i was BOILING white smoke from the exhaust. But guess what, head gaskets were fine, didnt even change them out....i had head bolt failure where the bolt head cracked just enough to allow the coolant to come up the threads and enter the head via that exact path. So again, just because you have coolant in your oil does NOT mean 100% that you have head gasket issues

Alex.currie44

I don't care where the coolant came to and whether your head gaskets "were fine". The fact is to get into the cylinder the coolant has to pass under or over the head gasket to get into the cylinder so if the bolt failed compression on the gasket was lost around the cylinder bore and into the cylinder it went. Semantics maybe but in the end it got by the gasket one way or another.

As to the other you just made another statement but did not answer the question.
How does coolant get into the oil if not by means of a failure of the head gasket or a crack in the head or block which allows coolant into the oil system. I am interested to know.

jptaylor

what part are you not understanding? do you know how the oiling system of an internal combustion engine works? If you leave a head bolt completely out of our engine, just the open threaded hole, and lets just say that the head gasket held fine under those conditions, the open threaded hole does NOT just bottom out blindly into the block but is open on the other end INSIDE OF A COOLANT PASSAGE....At this point coolant would travel up through the open hole onto the top of the head(WHERE OIL IS CONSTANTLY BEING SUPPLIED), mix with the oil, and then drain back to the oil pan to be recirculated with the oil.....Oil also lubricates the cylinders so the pistons dont seize in their bores...the piston rings to a good job of keeping most of the OIL from blowing by but even still there is going to be some oil that gets past the rings...but now you have COOLANT IN YOUR OIL which is being used to lubricate the cylinders...piston rings do NOT do a good job of keeping water/coolant from blowing by so you get WHITE SMOKE FROM THE EXHAUST even though your head gaskets are perfectly fine....

....if you open your oil fill cap as soon as the engine is turned off and you have steam coming from the cap then chances are coolant is entering your head in this manner as if it were a head gasket issue the coolant would be entering the cylinder, not the top of the head.....

Ludedude

Y'all are also ignoring the elephant in the room...not a gasket or bolt (not likely as it's a FL car) failure at all but a crack somewhere in the head or the block. This is all speculation though until we hear anything back from the OP and get his/her findings.

simandang

hey all sorry for the delay

Before getting the oil changed, I started the car after cold start and let it idle for 10 min and looked at the cap and it looked dark and no chocolate milk or milky residue. For peace of mind I had the oil changed yesterday and everything looked good and the coolant levels are perfect no leaks anywhere.

So last night we went out again and once again under heavy acceleration there is slight smoke but it is BLACK and NOT white according to two different people behind my car.

Does this black smoke indicate a oil leak somewhere? I am smelling oil smell from inside the car sometimes after spirited driving.

I have to say before the first episode of this smoking the car has sat around for a long time and not been driven aggressive at all. In fact I just started using M mode less than 800 miles ago.

jptaylor

If it is just a puff of black smoke only when you matte the throttle and it downshifts and jumps that is not that big of a deal, as I said earlier ALL engines have a little bit of blow by....if it is pretty constant then it may be that the valve stems are leaking oil by or something similar

Alex.currie44

I think I suggested that but it is apparently it is a head bolt.

jptaylor

No one said what it was or wasn't ....what I DID hear someone say though was that after you threw out big words at someone in an attempt to sound more knowledgeable than you are and also just to be an *** you got checked, but instead of manning up about it you decided to again be a smart ***....when you are done Googling how an internal combustion engine works please jump back in the fray(damn I feel like I just had a BLKRKT moment, all Thread Gangsta and ****)