Pontiac Repair: 2002 Grand Am overheating, intake manifold gasket, coolant systems

Question
QUESTION: Hello,
A friend's '99 Grand Am had a 2002 3.4 liter F.I. V-6 with 50,000 miles on it installed in 2003. This October it started overheating. He replaced thermostat and water pump, discovered intake manifold gasket leak, replaced those gaskets per GM procedure and with recommended GM parts, sealants, etc. There are now no visible external leaks. After all that, car still overheats (From cold, and with 50/50 glycol water mix, warms to 200 in driveway with no indication of trouble, but only makes it a block to a mile under normal driving conditions before temp shoots to 240 and reservoir cap valve opens.  Dexcool was removed and system was flushed at first sign of overheating.  GM 3.4 air bleed procedure has been done after every repair and overheating event.) No oil showing in coolant, no coolant showing in oil, no white or otherwise abnormal exhaust.
Question 1:  Which way is the spring end of the thermostat supposed to face in this engine's thermostat housing, toward the block or toward the radiator?
Question 2: I think the next step should be replacement of the reservoir cap.
Question 3: I've read online that the reservoirs for these coolant systems had a problem with roughness in the plastic of the filler neck. Is that repairable or is reservoir replacement required?  
What other possibilities can we check out?  Thanks very much for your advice, your time is greatly appreciated.

ANSWER: Hi Norman:

well a few things these engines are hard to bleed the air out of as you already noted. The thermostat can only go in one way. the spring faces the hot water in the engine. If this has had a history of overheating then my guess is it has some sort of a mechanical issiue like a headgasket leaking or a cracked head,block etc...  there is a product you can but at the parts store that you add to the cooling system and if there is exhaust gases getting into the cooling system the product changes color and that way you know if you have that kind of an issue or not. Another thing when this gets hot does the electric cooling fan run? If not then you need to look at that too. As far as the overflow bottle being the issue I doubt it it has been fine for 9 years and now an issue crops up with a bad plastic casting?? I don't think it's the overflow cap either it may leak but it also is purging off the excessive pressure from overheating. Good luck :)

---------- FOLLOW-UP ----------

QUESTION: Hi Todd,

In answer to your question on the fans, here's how they seem to run: Engine cold = no fans, engine warm to normal = low fans, engine overheated = full high fans.  I don't know if that's normal, I'd appreciate your letting me know.

We've been told two air bleed procedures, one says with engine cold, leave reservoir cap off, open bleed screw, bleed until coolant stream from bleed valve is continuous, close, start engine, wait for heat in upper radiator hose, add coolant mix if needed to bring level to or just over full cold mark of reservoir, install reservoir cap.  The other procedure says with coolant level at or just over cold full mark, engine warm and running, and reservoir cap on, open bleed screw until bleed stream is continuous, wait five minutes, repeat air bleed, repeat until air is gone. Please advise how you would bleed the system in our situation.

Thanks very much for the idea on the chemical to test for exhaust in the coolant, we'll do that next.  

Answer
either one of those proceedures will work to bleed out the air. I usually do this leave the bleeder open fully fill the overflow tank up about 3/4 of the way untill the air is gone and just water out of the bleeder. close the bleeder start the engine and run it up arounf 1,000 rpm's and keep an eye on the over flow if it goes down add a bit more. I make sure the hvac is on vent and hot and wait to see if there is hot air out of the vents. when it starts to feel warm i lower the rpm's down to idle and then crack open the bleeder again untill just coolant flows out.. then close the bleeder top off the coolant and put the cap on and let it run and idel and make sure it doesn't overheat. The fans seem to be working correctly.