Recently bought this 2007 PT Cruiser for a pretty decent price. Checked under the hood, all around the car and test drove it like I stole it and everything checked out for the most part. Obviously with it being used, I anticipated it probably needing a few things tended to. After driving it the next day for quite some time I parked outside a walmart and noticed this bubbling noise coming from under the hood and before even getting it opened up to check it out I was greeted by a rather uncomforting streaming puddle of coolant. Coolant was leaking out of the reservoir tank. I replaced the thermostat, the radiator cap, drained then flushed the coolant system filling it up with the HOAT approved coolant these Pts require, changed a faulty camshaft sensor, had a random misfire from bad spark plugs so replaced those, noticed the PCV vacuum hose looked rotted with cracks starting on both ends so obviously replaced that, rotors were rusted and thin so bought new ones and replaced those + pads... There is a significant difference in the way she drives now as opposed to before... Except after driving for awhile I think I jinxed myself bc I made a remark about how there wasn't any indication of overheating or bubbling from reservoir when turning car off then suddenly the temp gauge starts to slowly creep up to the third line.. Still no bubbling, but noticed the reservoir tank seems to fill pretty quick even before car warms to 50% and it seems to drain exceptionally slow back into radiator after cooling... What could be causing this??? Car only overheats if I've been driving sporadically where I've gassed rpms to about 3000 continuously or have been driving at highway speeds for long stretches... No signs of a cracked or blown gasket, no coolant in oil or oil in coolant, no obvious leaks under car, no white smoke from exhaust and the temp gauge hasn't ever gotten beyond the third line.... But I always pull over and sit for a good while to be safe if it does... Oh yeah and I forgot to mention, if the temp gauge has started to rise(which specifically only happens when at an idle after those previously mentioned conditions) if I begin driving again, the guage drops back to 50%...
Thanks for any ideas!!

 

There can be many different causes of overheating. Are the fans kicking in when they should? They don't operate all the time, but are supposed to kick in under certain conditions determined by the computer.

Is the outside of the radiator clean and allowing good air flow through it?

Has the cooling system been properly bled of air? (It ought to bleed itself after several warm-up and cool-down cycles).

Proper mix of anti-freeze and water?

Proper temperature thermostat properly installed (not put in backwards) and tested to make sure it's functional?

Proper pressure cap?

Functioning water pump?

 

does the fan come on? does it come on when the ac is on?

 

I'll check the outside of radiator to see if its cleaned. I'll go ahead and replace water pump just in case too. Everything else is good.