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Discussion Starter #1
Just finished installing TW heads, GT40 upper/lower, TB, MAF, etc…. on my 91GT. I started the car with the radiator full and the cap off, after setting the timing, TPS sensor, and idle, the car ran smoothly but continued to get hotter. When coolant started running out the radiator I put the cap on. The top hose then pressurized but was very cool. The temp reached 250° and stayed at that point for one to two minutes, I then shut the car off. While the car was running the coolant overflow container filled and was burbling(air) over.

I’m assuming I need to get the air out of the coolant system, what is the best way to do this?
 

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I fill the system with one of the heater hoses disconnected. When the coolant starts to flow out the hose quickly reconnect it. Has always worked for me.
 

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make sure there is no air trapped in the engine,if you didn`t bleed it ,then there is no coolant underneath the thermostat to heat it up and it stays closed and overheating occurs.just by filling the rad you can`t get all the air out.I usually do it by loosening a plug or the sensor for temp on the intake until all the air is out!
 

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Discussion Starter #4
CobraII, I will try the coolant sensor on the lower intake, do you do this while the car is running or engine off?

Thanks
 

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Not to be a smart-ass, but the thermostat isn't in backwards is it? The top hose should not be cool after the car comes up to temp. Maybe I'm missing something here.
On my last install I drilled two small holes in the t-stat housing to let air bleed into the top hose by itself. This is a little cleaner than opening a bleed somewhere in the heating system or the block. Good luck.
 

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Yes you can do it while it is runnnning,but it is not necessary.you see when you fill your rad,the thermostat is closed (everything is cold)then the coolant goes in the engine thru the bottom hose and makes it way up until the air pressure trapped in the engine builds up and stops the flow ,the rad is full to the rim but if you have air trapped you`ll see when you open a plug or loosen a sensor ,air will come out and the level will go down in the rad .when it is bled,then plug it back.one last thing make sure that the filler neck of the rad is the highest point of the system I saw a rad installed very low in the engine compartement and the water passages of the intake were higher than the neck,but I don`t think this would be an issue in your case.
Good luck
 

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I have always just drilled a small bleeder hole in the thermostat near the top to let air escape. Works well when its allready apart though
 
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