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96 LT1 over heating issue

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Old Jan 4, 2011 | 07:41 AM
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Default 96 LT1 over heating issue

I recently flushed my heater core, after i was done i filled up the radiator and bleed the system per the instructions in my owners manual.

For the last two days, when i go out to my car in the morning and check my radiator level before i start it up the fluid is low. Ill fill up the radiator and bleed the system again This morning i didn't check the level thinking that since i haven't had any heating issues that everything would be ok. I started up my car to warm it up and went inside for about 10 min. When i came out, my car temp gauge was nearly pegged at 260 and my check gauge light was on. I turned off the car and felt the radiator cap and it was cold. I slowly start to twist it open and fluid started to come out, so i know the radiator was full. I opened up the bleeder valves and a good amount of air came out (more air came out from the top bleeder). Once the system was bled i started up the car and the temps went down to normal.

So what could be causing air to keep getting into my cooling system? Or is there normally alot of air in the system after a heater core flush that requires the system to be filled up and bled several times? Thanks
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Old Jan 4, 2011 | 01:21 PM
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You have coolant going into the engine due to either a cracked head, or (more likely) a blown head gasket.

(Ask me how I know...)

Pull the heads; you'll find your problem.

Sorry.
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Old Jan 4, 2011 | 04:37 PM
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Would there be any other clues as to if it is a cracked head? Is there a test i can performe to verify? Thanks,
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Old Jan 4, 2011 | 08:52 PM
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Check your oil-see if it's colored like oil should be, or is it milky/discolored? I went through the same thing you did, only my problem was the t-stat wasn't opening and that was the cause of my overheating. The coolant was lower in my car the next day because after I parked it, the car would vomit the super-hot coolant. I'd recommend looking into the oil first, then the t-stat and bleeding. Bleeding LT1's isn't as easy as you would think it is-I sure as hell didn't get all the air out on the first attempt...
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Old Jan 5, 2011 | 07:19 AM
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Curious, is there any amount of water coming out the weep hole on the water pump?
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Old Jan 5, 2011 | 02:23 PM
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Originally Posted by frack
Curious, is there any amount of water coming out the weep hole on the water pump?
I got under the car to check it out and saw no water comming out from the weep hole. I did notice some radiator fluid on the front of the engine and collecting at the oil pan. I cleaned it up and will check it out again later to see if there is more there. I want to rule out the fluid being there as a result of me bleeding the system.
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Old Jan 5, 2011 | 02:26 PM
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Originally Posted by myk
Check your oil-see if it's colored like oil should be, or is it milky/discolored? I went through the same thing you did, only my problem was the t-stat wasn't opening and that was the cause of my overheating. The coolant was lower in my car the next day because after I parked it, the car would vomit the super-hot coolant. I'd recommend looking into the oil first, then the t-stat and bleeding. Bleeding LT1's isn't as easy as you would think it is-I sure as hell didn't get all the air out on the first attempt...
I had an LT1 once that did that, Had milky brown gunk built up under the oil fill cap and everyonce in a while it would vomit coolant from the over flow tank.

However with this LT1 i don't see any of that. Ill get a new T-Stat just to rule that out.
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Old Jan 5, 2011 | 02:37 PM
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Ok so this morning I went out and before i started my car i checked the level of the radiator. It was a little low but not much until i opened up the bleeder valve. The lower bleeder valve had no air in it. However the upper bleeder had alot of air and as it bled the air out the radiator fluid went down about and inch and a half. I filled the radiator up and bled the system again. never had an over heating problem this morning. Still a mystery as where the fluid is going and air is coming from
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