run hot on idle

[kip younger]

I finally got to the point of breaking in my engine (350); ran it for 25 minutes, at 1800rpm. RAN GREAT! No problems. No leaks. Temp stayed right at 185, until I brought it off the high idle. While I was messing with the idle mix screws on the front of the carb, the temp jumped right up. I shut it off at 210. This only took a minute or two to move up that fast. I checked the oil and its about 1/2 quart low, but I did not wait to see if more would drain down into the pan after turning off the engine. When the block was done at the machine shop, it was already bored out to 40 over, and the machinist took it to 60 over. Someone did say it could have heat issues at 60 over - but I did not think this type of spike is what they were speaking of. The radiator is fairly new, but it is whatever the original was - single or double core? Do I need a bigger radiator? I thought that I had let the car run enough prior to breaking it in, to "burp" the radiator. The timing is about 9 - 10 advanced. I do not have electric fans on the radiator, but the engine fan seemed fine at the higher rpm. Any thoughts?????? thanks - kip

[gmjunkie]

Originally Posted by kip younger

I finally got to the point of breaking in my engine (350); ran it for 25 minutes, at 1800rpm. RAN GREAT! No problems. No leaks. Temp stayed right at 185, until I brought it off the high idle. While I was messing with the idle mix screws on the front of the carb, the temp jumped right up. I shut it off at 210. This only took a minute or two to move up that fast. I checked the oil and its about 1/2 quart low, but I did not wait to see if more would drain down into the pan after turning off the engine. When the block was done at the machine shop, it was already bored out to 40 over, and the machinist took it to 60 over. Someone did say it could have heat issues at 60 over - but I did not think this type of spike is what they were speaking of. The radiator is fairly new, but it is whatever the original was - single or double core? Do I need a bigger radiator? I thought that I had let the car run enough prior to breaking it in, to "burp" the radiator. The timing is about 9 - 10 advanced. I do not have electric fans on the radiator, but the engine fan seemed fine at the higher rpm. Any thoughts?????? thanks - kip

Check the Fan Clutch!! Will it wiggle,How much drag dose it have when you try to turn it??

[kip younger]

there is no wiggle, and there seems to be a steady drag on the fan... it almost acted as if it stopped getting water into the block when the idle slowed down... but it ran fine at the higher rpm?????

[Lady N]

My when is iddle runs 210 to 220 it seems ok, down the road is 190 , but like gm junkie said check your fan clutch again specially is your a/c is not cooling well when is on idle mode. c3 are hot by nature anyhow.

[Rich Z]

I think sitting at idle with no air movement through the radiator, minimal movement of fluid through the cooling system, and the engine still generating significant heat may be a natural recipe for overheating.........