IceScraper

I just picked up a 2009 ML63 two weeks ago. Managed to get some items sorted out. Replaced the coolant reservoir cap with a new one because the old wasn't sealing anymore. Thinking this was the source of our leak, (coolant evaporated).

But I still have this persistent coolant leak every couple of days I'll get a message to top up coolant level. So of course, I do, and then again I get the message a few days later.
It's coming from somewhere, (please don't let it be headbolts) but from where I have no clue. We don't see anything dripping out of the bottom of the engine bay or really from anywhere. I don't have any puddles in my driveway. The only thing is you can smell the coolant after you shut it down and park it. Exhaust seems fine doesn't overall smoke or anything abnormal, (it smokes slightly, but it is winter).

What have I got myself into? Coming out of trouble free Lexus. I knew there would be things being a Mercedes, but seriously? I am having the dealer I bought it from look at it tomorrow.

I need to have a shop pressure test the coolant system. The one I visited today was pretty sure it was headbolts but couldn't get their pressure valve to seal on the coolant reservoir to perform the test. Let's hope its faulty reservoir tank or cracked line somewhere.

Fingers Crossed

Solo wing

I once saw an SL63 (M156) with the head bolt issue, however, the coolant wasn't going into combustion chamber or into the oil. The coolant was leaking between the engine block and the engine heads beneath the intake manifold, so it was an external head gasket leak due to the head bolts.

Good luck.

IceScraper

Thanks for the info. Oil doesn't seem contaminated with coolant either. I do keep smelling coolant whenever I drive it for extended trips to and from these mechanics shops. I'm afraid of driving the car now considering some of the things I've read about possibly hydro-locking the engine. I do also have a small weeping oil leak coming from valve cover gasket on the right side of the engine. I have an estimate in my hand for almost 3k, (950 for parts and 1800 labor) from a knowledgeable mechanic in my area to do the head bolts and replace all the gaskets while we are in there.

Oh yeah, also the transmission pan is rusting and could use changing down the line. Should I go ahead do other preventative maintenance while we have everything apart? To be honest, I haven't done much research on the cam's phasers yet, only briefly skimmed over it.