[Wilder One]

2014 with 110,000 miles on it. This happens when the car is off and has been sitting at least 30 minutes. There's a loud pop (like a muffled balloon pop) then smoke condensation comes out from under the hood. Lasts a few minutes and then is gone. There is no distinctive smell to it, oil, fuel, freon, coolant, etc. The first time it happened I thought it was on fire, but there was no burning smell. I can't find where its coming from, there is no visible signs of moisture, etc in the engine. It keeps happening every week or so... No issues overheating. The last time this happened, the car sat outside in 27 degree weather for an hour while we ate dinner. When I opened the door, heard the loud pop and smoke came out. Car was a little hard to start afterwards, but no issues driving it.

Car does not have airmatic system. Had the coolant system flush, thermo housing and water pump replaced recently. Replaced charcoal canister recently as well.

 

[tonylinc]

Wow, that is a wild one. I at first thought it was the Airmatic until I saw you say it doesn't have Airmatic. Mine with 192K miles is perfect. Once in a while I hear it let a little air out, like those semi trucks letting off a little extra air from their brake systems now and then. But no problems. To find your gremlin, you might have to drive it one day, park it, open the hood, pull up a lawn chair and watch and wait a while and hope to be looking when it does its thing?

 

[amusa]

I would check the spark plugs.

 

[bobby735]

Sounds like "heat soak "... (engine gets hotter once it's shut down).. The problem is catching when it does it.. and where it's coming from... I'm thinking,.. dust the entire engine compartment with some like chalk dust.. or a piece of cardboard over the whole compartment to try to catch a stain,.. or a camera under the hood with a DVR... or like Tony said,.. lawn chair with the hood up... My guess is it's coolant even though you can't smell it.. But then again,.. I'm just guessing... Good luck, ..be sure to let us know what's the out come...

PS,.. I'm over here because I'm thing of replacing the wife's w163 with a newer ML.. and what to aspect in the way of problems..