I have recently purchased a 2006 Mercedes Benz ML500 W164 with approx 215K KM/130K miles on it.
A few days ago I was showing it to a friend who after a drive inspected the engine and mentioned he thought it was a little hot in there when I opened up the engine bay.
I've never had any sort of engine overheating warning and today I was keeping an eye on the temp gauge and it didn't really go over 84-85 degrees celcius.
However, yesterday after I got an oil change done with 0w40 synthetic Mobil 1 oil and today I also noticed it just seems extremely hot in the engine bay like the metal components in on either side which lay a little lower and are slightly brown in color from being so hot in particular when I sprayed those with a hose today released quite a large amount of steam and sizzle noise when they came in contact with water. Also in front of the plastic cover those metal components and the large rubber hose get quite hot as well. I know water starts to steam around 80C but boils at 100C so that metal down there had to have been at least 110C in temperature to turn water to steam like it did so quickly.
When I decided to hose it down with cold water quite a substantial amount of steam came from the engine.
Should I be worried?? I know engines are supposed to run hot and this is a big V8 but should they be producing this much steam when contacting water? I am a bit paranoid now as I purchased the car as a family vehicle and now sort of hesitant to drive it and feel more comfortable driving my chevy malibu.
Edit: After some research I believe that really hot metal component on either side of the engine that sits lower is called a "catalytic converter". And it was probably the hottest (released the most steam when sprayed with a hose).