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Old Feb 27, 2011 | 12:13 PM
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Default Cooling system problems

I'm having some strange issues with the cooling system on my '99 trans am. I can top the radiator off one day and it'll be low enough to trigger the low coolant light when I start it up on the following day. I can't find any external leaks, not even on the front or rear crossover tubes, I've already used a pressure tester. I've already replaced the cap and the radiator

It does push the excess coolant into the overflow container when it heats up, but it doesn't seem to be sucking it back into the radiator as it cools off. Every time I top off the radiator and drive it, it pushes more water into the overflow to the point where it's blowing water out of the overflow. Also, when I remove the cap after the car is cooled off, the overflow container erupts like a geyser.

Anyone have an idea why the cooling system isn't sucking the water back from the overflow container?
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Old Feb 27, 2011 | 02:14 PM
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Well its sounds like you have air in the system,possible headgasket...
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Old Feb 27, 2011 | 04:15 PM
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crud and dirt in the over flow tank preventing it from flowing back?
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Old Feb 27, 2011 | 05:10 PM
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ive experienced this as well as others have too.. check to make sure the pipe that goes from the crossoverpipe and the pipe that goes to the overflow arent switched..meaning the hose from the crossover should be on the bottom, and the overflow should be on the top fitting on the radiator. did the exact same thing to me, and was boiling out of the resevoir
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Old Feb 27, 2011 | 05:48 PM
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also the hose that runs under the battery is a spot that loves to leak...pull the battery and check it out.
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Old Mar 2, 2011 | 07:04 PM
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Thanks for the replies. I actually swapped the overflow tank and hose from my '95 camaro with the one in my trans am since they seemed to be the same. I've driven it for a few days and noticed it's still filling up my overflow tank without suckin any back in.

99hugger, I did a compression check a few weeks ago, all cylinders were within 10%.

Jayz, I've never actually touched those hoses, but they were on correctly. I haven't done any tinkering on this car, any money I have for mods goes to my '95

If the water pump was seeping just a little in the weep hole, could this cause enough of an air leak that on cool down it's sucking air instead of coolant?
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Old Mar 2, 2011 | 07:21 PM
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Yep i had the same trouble and it was the water pump gaskets. GM has updated ones.
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Old Mar 2, 2011 | 07:59 PM
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it could be leaking through the weep hole under the water pump but if u have air in the system its going to block the flow of coolant and **** out to the overflow there is a small bleader screw on top of or near the thermostat that u should open when idling the car and when there is a solid stream of coolant coming out u should b good another thing to check is when the car is cold take off radiatior cap and start the car and look inside of radiator there should b a steady stream of coolant flowing through the small hose going into top of the radiator just a question have u overheated the car at all?????
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Old Mar 5, 2011 | 01:57 PM
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Originally Posted by O2Form
Yep i had the same trouble and it was the water pump gaskets. GM has updated ones.
Thanks, with 170k miles on the car and the original water pump, it may be worth replacing it just to take a blind shot at fixing the problem.

it could be leaking through the weep hole under the water pump but if u have air in the system its going to block the flow of coolant and **** out to the overflow there is a small bleader screw on top of or near the thermostat that u should open when idling the car and when there is a solid stream of coolant coming out u should b good another thing to check is when the car is cold take off radiatior cap and start the car and look inside of radiator there should b a steady stream of coolant flowing through the small hose going into top of the radiator just a question have u overheated the car at all?????
I did have some problems with the car overheating a few months ago due to a giant air bubble that seemed to be behind the thermostat. I replaced the radiator because it was pretty corroded and I haven't had the overheating problem since. I just never fixed the problem with it not sucking water back from the overflow.

I do have a steady stream of water coming from the top of the hose ever since I replaced the radiator. I'm thinking of replacing the water pump just to take a blind shot at it.
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Old Mar 5, 2011 | 02:37 PM
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My water pump was ok but the gaskets wooooood leak as the engine was warming up then stop once it got warm. GM has updated gaskets.
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Old Mar 5, 2011 | 05:01 PM
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anybody got a PN on the new style gaskets?
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Old Mar 12, 2011 | 07:17 AM
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what year is your car 02form? My car had the metal gaskets already on it, not the paper ones. Was the paper gaskets that got updated or does GM have different versions of the metal ones?

I replaced my waterpump a few days ago and the old one had signs of dried coolant that had been running down from under the pulley and also from above the water pump. It didnt look like anything had been leaking from the old gaskets.

Though I still have the problem with it not sucking water back from the overflow tank
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