LT1-LT4 Modifications 1993-97 Gen II Small Block V8

cooling problem please help

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Old Sep 9, 2007 | 05:10 PM
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Default cooling problem please help

I recently finished a complete tear down and rebuild on my 1996 z28, after minor problem after problem I have everything ironed out except I now have a cooling problem. My thermostat is opening, and my fans are coming on. My car will run at normal temp. but the overflow tank will puke out coolant, thinking I overfilled the system I let it go, and ran the car to temp again, this time to have the car overheat. Myself, another long time f-body owner, and a friend who is A.S.E certified G.M tech burped the system, so an air bubble seems unlikely. This is all that is keeping me from enjoying a car I purchased five months ago and have not been able to drive, so any advise would be appreciated.
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Old Sep 9, 2007 | 05:27 PM
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What temp is "over heating" to you? Some people say that even though it's normal.
You guys using the bleeder screws to bleed the system or just squeeze the pluming?
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Old Sep 9, 2007 | 05:29 PM
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check the integrity of your coolant lines, you'll know if they need replaced if they are collapsed(spelling?). Your Thermo maybe is the failsafe position it (fully open) for the price its the cheapest place to start, first make sure your fans come on, like I said the thermostat, and check the hose.
I'm not sure weither these cars have a second thermo with the coolant lines.

I have a 180 stat and I run 185-195 I don't think I have ever reached 199+ though oh yeah even maye you shoud try and bleed it so more (people aren't perfect it could still have air i nthe system too, do you know where your bleeders is its hard to explain but someone will prob post that Help! pic that someone asked about b4

Last edited by Fbodynightmare; Sep 9, 2007 at 05:35 PM.
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Old Sep 9, 2007 | 05:52 PM
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The temp went up to 260, and we used the bleeder screws. I have the 185 thermo in the vehicle. And thanks for any help you can give.
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Old Sep 9, 2007 | 07:01 PM
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Try getting the front of the car up in the air so the bleeder screws are the highest point in the system and bleed it again.
Did you get all the hoses on and in the right places?
Is the water pump circulating the coolant?
Are the head bolts tightened down fully? check the oil for water contamination.

Sara Lou
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Old Sep 10, 2007 | 09:19 AM
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check your radiator cap.
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Old Sep 10, 2007 | 09:59 PM
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Default still havin trouble??

[QUOTE=Fbodynightmare]check the integrity of your coolant lines, you'll know if they need replaced if they are collapsed(spelling?). Your Thermo maybe is the failsafe position it (fully open) for the price its the cheapest place to start, first make sure your fans come on, like I said the thermostat, and check the hose.
I'm not sure weither these cars have a second thermo with the coolant lines.
And check your cap


What have you done to fix this snice you last posted?
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Old Sep 10, 2007 | 10:20 PM
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I don't want to alarm you, but I had a friend with a 1997 formula that had a similar problem, believe it or not it was air in the system, he could never get it out of the system and engine would overheat...... it resulted being a cracked cylinder head, almost between the valves... when the piston would go up as fuel and spark ignited.... it would "pump" air through that little crack, creating an air gap that would not allow coolant to travel by the blocks water jackets, producing an overheat situation. It may be hard to believe, but the oil never got milky or anything. I hope its not your case. Good luck solving the problem.
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Old Sep 15, 2007 | 10:54 AM
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sewell z28's Avatar
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Thanks for all your help, the problem was a combination of small things. First my radiator cap had gone bad. Second I had a line that was not tight. And last and probably the one that will make you laugh, the coolant overflow line and the water pump return line were swaped. I guess it goes to show no matter how many times you do something you can still make a bone head mistake. Final got to drive the car, and I love it. Ported heads,intake, lt4 hot cam, long tubes, cai, 58mm NOS throttle body, tubular everything, a realy fun daily driver. Thanks again.
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