Hey everyone. I've tried searching before asking, but coming up short. 06 HHR with the 2.2. Car runs great, and then will randomly start to hesitate and sound like it's missing. Besides checking all of the obvious things, when I pull off the coil set, the spark plug hole/well on what I believe is cylinder 1(closest to driver side) is full of coolant - that's BEFORE taking the plug out. I vacuum and use paper towels to dry it out before pulling the plug out and the end of the plug is bone dry. I've put that plug back in as well as trying new ones, and the car will run like new for quite a while and then same thing, plug "well" fills up with coolant and misfires on that cylinder. I've replaced the coil set/pack, valve cover gasket, plugs, flushed the coolant system, nothing fixes the issue. I'm also not seeing any common hints at a head gasket - water in oil or visa versa. I'm lost, maybe it is a head gasket or cracked head? Just looking for advice before I start throwing a bunch of money at it.

 

Welcome
You need to pressure test the cooling system. Find the leak and repair. My guess is a hose leaking.

Edit. Cyl. #1 is closest to passenger side. #4, drivers side.

 

#1 is at the "front" of the engine; i.e.: where the serpentine belt is, passenger side.
I can't think of a way coolant could collect there from the inside of the engine. Maybe you have a hose spurting. Is the spark plug tight? Any CheckEngineLight?

 

See how the spark plug lives down in the head , just oil around there. But might have a coolant jacket in there somewhere

 

Guess they’re not coming back.

One and done.

 

Anybody out there? Figure it out? Be nice to know for future reference