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Coolant does not return to radiator

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Old Sep 7, 2007 | 07:03 PM
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Default Coolant does not return to radiator

First post... I know. I'm not an Ls1 guy, but haven't been able to convince my buddy to post, so I'll ask a question for him.

99SS, built motor turbo etc, 44k on chassis. He purchased the car modded, so I cannot say it the radiator that came in it was stock. That radiator burst a few months ago and he replaced it with a new one. FWIW, the new one has what appears to be ports for a transmission cooler which he does not use.

It appears that his coolant will not return from the coolant overflow bottle. He NEVER has to add coolant, but he does have to transfer it from the overflow, back into the radiator. Most every time he drives the car he begins by transfering coolant from the overflow into the rad to top it off. If he doesn't do this, the low coolant light will come on. He has tried numerous caps (18psi I believe), zip tieing the lines, etc. It doesn't disappear, and in several months of dealing with this, he has not actually added extra water from the tap or anything.

So if it's not disappearing.... why is it not returning from the overflow bottle after the car cools down? Is this a manifestation of in proper burping? He has tried that numerous times according to what he has read on here with no change.

TIA

-Chris
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Old Sep 10, 2007 | 02:05 PM
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Originally Posted by carx7
First post... I know. I'm not an Ls1 guy, but haven't been able to convince my buddy to post, so I'll ask a question for him.

99SS, built motor turbo etc, 44k on chassis. He purchased the car modded, so I cannot say it the radiator that came in it was stock. That radiator burst a few months ago and he replaced it with a new one. FWIW, the new one has what appears to be ports for a transmission cooler which he does not use.

It appears that his coolant will not return from the coolant overflow bottle. He NEVER has to add coolant, but he does have to transfer it from the overflow, back into the radiator. Most every time he drives the car he begins by transfering coolant from the overflow into the rad to top it off. If he doesn't do this, the low coolant light will come on. He has tried numerous caps (18psi I believe), zip tieing the lines, etc. It doesn't disappear, and in several months of dealing with this, he has not actually added extra water from the tap or anything.

So if it's not disappearing.... why is it not returning from the overflow bottle after the car cools down? Is this a manifestation of in proper burping? He has tried that numerous times according to what he has read on here with no change.

TIA

-Chris
He has a vacuum leak in the system. That's really all it can be. He needs to double and triple check all of his lines in his cooling system. That'd be the only reason for that not happening. The overflow principle works on vacuum.

From what I underlined, I'd say the devil lies somewhere in those details. He's probably overlooking something really small.
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