I heard some weird rattling noises coming from the 98 today, out of nowhere...

It did not seem consistent with the speed I was travelling, nor the engine revs, then and after a few minutes, it went away.

I also noticed a bit of clunky noises when turning into a carpark (left turn).

really odd. Car is running just fine, no problems. I'm thinking exhaust rattle or something like that?

What makes it weirder is that once I got home, put the car in the garage and I swear I could hear some hissing and groaning noise from the front somewhere, I can't figure out where. Now, I understand the normal coolant heating overflow process, but I've had this car out on much hotter days without issues.

Any ideas what might be going on...?

I'm fairly sure I used to hear a milder version of the rattling noise a while back, only in noticeable in neutral when stopped at the lights - only today it was very predominant, even my wife could hear it, so I'm not imagining it Chris !   

much noisier today, much more regular.

You wanna hear something really weird?......How about a Justin Bieber CD with the volume at 180 db.....

 

that's not weird, that's torture!!