Inconsistent overheating on 2001 Mustang GT

Whenever I'm out driving nothing happens, but as soon as I'm parked for a few minutes the temperature gauge starts rising noticeably. Start driving off again and it cools down again.

Bad water pump? Clogged cooling system? Don't think it's the fans, but I'd have to check again. I have noticed some smoke coming from the area between the back of the intake manifold and the firewall so there's presumably a leak, but nothing's ever hitting the ground. While this is happening, I have noticed an odd 'pepperjack cheese' smell that goes away when the car cools down.

God I hate this car.

My guess is thermostat. It's broken or sticking and the increased pressure from driving around forces more coolant past it and increases airflow enough to compensate for the restriction. 

Sounds like the fan to me.  Impeller on the pump,  t stat. All possibility's. 

I have also noticed my A/C's been very weak and kinda crappy/warm. Not sure if that helps simplify the problem down

My guess is the CCRM (constant control relay module) that controls the fans (and ac!) 

I've had this happen with just a bad radiator cap.  When it no longer held pressure it would do exactly what you describe.

How are your coolant fluid levels?  Are you loosing coolant?  But, not dripping coolant onto the ground?  

I have also replaced the radiator cap recently as well as the radiator itself (water pump too - all of this has been done within the last 5k miles).

When the car does overheat, I loose coolant in minor amounts - but yes, none of it hits the ground

In reply to Dootz :

That's normal if the engine is shut off.

Engine running, check fans.  Most don't tun on till around 200+F.  So again, could be normal

In reply to iceracer :

Switch the ac on with the ignition on/car off.... 

Fans should come on. 

In reply to Dootz :

Have you burped the system? It could have air trapped air in the system. 

I did burp the system before (and there were definitely air bubbles), but the issue remained (just a slight improvement)

Dootz said:

God I hate this car.

I had a 2001 Mustang GT. Beautiful, reliable car. Ran 13s in the quarter-mile 100% stock, and would do 155 mph (indicated) on a long-enough stretch of highway.

Drove it for almost 7 years, and the only thing that ever broke was the stupid little idle air motor.

How are you measuring the temps to know it is overheating?  

I would +1 the advice to check the fans based on your symptoms. Sounds like a bad CCRM could be responsible for all your symptoms.

In addition, check the back passenger side of your intake where the heater hose connects in from the firewall - those are known to crack. 

Did you fill up the coolant passage on the back of the intake before putting on the heater hose? That’s the coolant fill procedure from the factory service manual. I’ve never seen it on any other car, so I wanted to mention it. I had good luck using that method to start and then putting the from two wheels up on ramps.

I'm also betting fan.

Air bubbles in the coolant most of the times is from a weak head gasket.

Sounds like a fan issue.  Since your car is new and doesn't have a fan clutch, I vote CCRM too.  Ever since Ford started using them on the 94s, I've always kept a spare around.  

Found fan to be shattered :/

So we all were right, at lest most of us.

  curious as to how it got shattered

Beats me - the propellers are all connected to another, but they're all broken off the center spinning mount as a whole

Very strange

Intake manifold/thermostat housing likes to break on these motors so I would check that first thing.

If that isn't it...

Just LS swap it and call it a day.

Had a similar issue with a V6 dodge shadow.  Farted around with everything until i noticed half my radiator fins were missing never leaked just would start getting hot.. fans were running etc.  Swapped to a different radiator never had another issue.