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Discussion Starter #1
I have a 70 302 coupe and have been having overheating issues. I have done the following:
1) new radiator
2) new heater core
3) new water pump
4) new thermostat 195* then a 160*. 160* is still in it.
5) new lower hose
6) new temp gauge
7) checked and confirmed correct timing
8) burped system several times.
As i did all of the above, the temp has came down. I can drive the car on backroads and temp will do ok. But when I drive it on hwy at speeds up to 70-75mph it will go up to 215*. I'm wondering if the 160* thermostat is letting the water flow thru the system to fast and not having time to cool down in the radiator. Even with engine temp getting up to 215* the radiator temp got as high as 195*. I have a temp gauge in the radiator cap. The engine will run 10-15* hotter than the radiator, which that is to be expected. I'm leaning on the thermostat needs to be changed back to the original 195*. What do you guys think ?
 

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Welcome to ALLFORDMUSTANGS!
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BTW, that’s a really bad$ss car. Absolutely love the body lines on this model.
 

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215F is a little hot but not overheating. If you are running 50% water, 50% antifreeze and it isn't boiling over, then there isn't anything wrong. Doing a real good coolant flush using a chemical that you leave in for 200 miles then flush three to four times with fresh water should lower that a little. Has to be done when the weather is above freezing and not too hot either.

You should use the 195 degree thermostat, not the 160. Ideal coolant temperature is 200F, and you want to get there as soon as possible so the engine oil gets in its ideal range. Oil temperature will lag behind the coolant initially, then pass it by 10-15F. Ideal oil temperature is 212F.
 

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195 - 215 is not hot.
I would also recommend that you power flush the block.
This is done my using compressed air with your garden hose to loosen and remove most of the scale inside your block.
There are many tutorials on YouTube to help you do this.
 

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A thermostat only controls minimum engine operating temp. Your temps are not high. I personally like a 180* thermostat.

On a side note, engine timing lean carb fuel mixtures can also cause higher running temps.
 

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Water going too quickly through the radiator to cool is largely a myth. Fluid speed actually helps with cooling, since it is mass past surface area that cools. To that point, pressure in the system is necessary to prevent steam bubbles, because bubbles in the coolant reduce the mass available to absorb heat. Having a thermostat helps build pressure by adding a restriction in the cooling system. Racers sometimes remove the thermostat to reduce horsepower losses from driving the water pump against the thermostat. Naturally, that's a bad idea for a street car where not that much heat is generated.

That said, how new is your radiator? It's possible that in the short time you've owned it, it's been plugged with junk from the engine.

Another possibility is that it's just hot where you live. If it's 95 degrees outside, then it's not unusual to see higher engine temps, even while cruising. Also, check to make sure your lower hose isn't collapsing. You may need to put a spring in the hose to keep it from collapsing at elevated rpms as the pump sucks it closed. To check, just rev the engine up while parked and watch the hose.
 
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Discussion Starter #7
I finally have the car running at a steady 205* at any speed. I changed the thermostat back to a 190* and cut my upper and lower hoses to get some of the bend out of them to get a better flow. I put in a new gauge and a new temp sensor, I can run the car at 75mph or 110mph and it never gets over 205*. It has stayed steady for the last few days, so I am satisfied I have it fixed. Thanks for the input.
 
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