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Discussion Starter · #1 ·
Has anyone else had issues with them not cooling well at idle? Mine works great for driving and brief sitting in traffic but leave it running in the 100* Texas heat and it starts boiling over.

Thermostat is 190, I know about the 160* but don't think that will help with the overall cooking. The SPAL fans are set to come on at 190 and off at 185. It does have steam tubes from both sides that flow into the radiator replacement right next to the filler neck.

It does t have A/C yet but does have an internal and external trans cooler. I am going to add A/C and know that this is going to compound the issues.

Anyone think of solutions? I have read the Dewitts are good radiators and I searched the group for similar issues, but didn't find much.
 

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1963 Nova SS and 1965 Nova
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Running 50/50 antifreeze and water? You might try a 180 or 160 t-stat but also experiment with the mixture of coolant and water. During the summer months something like 70% water and 30% coolant may work better for you. When troubleshooting cooling system issues it can really only be a couple of things. Not enough coolant flow or not enough airflow. Smaller dual fans are usually better than a single fan. Have a high flow water pump or stock? How are the hoses? Could the low side be collapsing? How accurate is your gauge? And what pressure cap are you running? All of these items come into play.
 

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Discussion Starter · #5 · (Edited)
Running 50/50 antifreeze and water? You might try a 180 or 160 t-stat but also experiment with the mixture of coolant and water. During the summer months something like 70% water and 30% coolant may work better for you. When troubleshooting cooling system issues it can really only be a couple of things. Not enough coolant flow or not enough airflow. Smaller dual fans are usually better than a single fan. Have a high flow water pump or stock? How are the hoses? Could the low side be collapsing? How accurate is your gauge? And what pressure cap are you running? All of these items come into play.
Brand new hoses, high flow pump, the dual spal fans that come with the radiator, gauges are very accurate through FAST 2.0 and it starts boiling over just above 232*, I will check pressure cap rating.
 

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With a 190° thermostat which is correct for an LS efi engine, you shouldn't have your fans come on at 190° and off at 185°. The fans would come on at running temperature and have a very hard time coming off at a temperature lower than the engine thermostat. A setting of 200° on and 195° is reasonable. How did you burb the system. Best way for the LS engines is one of the funnels like these ones. I would verify the temperatures with an infrared gun. 212° boiling doesn't make sense with the rad cap that should raise the boiling point.
 

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Discussion Starter · #11 ·
With a 190° thermostat which is correct for an LS efi engine, you shouldn't have your fans come on at 190° and off at 185°. The fans would come on at running temperature and have a very hard time coming off at a temperature lower than the engine thermostat. A setting of 200° on and 195° is reasonable. How did you burb the system. Best way for the LS engines is one of the funnels like these ones. I would verify the temperatures with an infrared gun. 212° boiling doesn't make sense with the rad cap that should raise the boiling point.
I started it and broke the steam vent loose until only liquid came out and closed it, once up to temp I cracked it opened again and did the same thing.

It has over 2000 miles since rebuild and initial burping so all of the air should have made it way to the top, and been released with the most recent bleeding, I would think.
 

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I would definitely buy or borrow one of the funnels that will ensure full purge of air. I've tried without doing it that way and could never get all the air out of engine.
 

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Discussion Starter · #14 · (Edited)
I bought it in May in PA drove it 2000 miles back to Central Texas and no issues. That was in moderate traffic and it would get up to 210 or so but no more. I drive it in 100 plus heat last week and stopped with the engine running for about 15 minutes and the hood up, some friends were giving it the once over, and noticed coolant on the concrete. Started driving and it cooled right back down.
 

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It may be a case of too much coolant in the system. Those top and bottom tank rads needs some room for the coolant to expand. What you see coming out may be excess coolant and not boiling over. On a conventional radiator in these cars, you don't fill the radiator to the top. You need to leave the level lower when cold so that there is room for expansion. You may indeed have all the air out but too much coolant.

I think I run 195° thermostats on both my LS cars and both run under 200° which is what the factory designed the engines to run at.
 

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If it stays cool at highway speeds but overheats while idling it would tend to point towards the fan(s) more than anything else. If it were a water flow issue or insufficient radiator it would probably be hot at highway speeds too.
 
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