coolent not returning to radiator

[2g_TalonTSI]

Ok ive got a 98 tsi and im having a problem with the cooling system. my car overheats every few days if i dont fill it with coolant. the problem is that it overflows into the overflow bottle when it gets hot but when it cools it wont suck it back into the radiator. i changed the rad. cap and the thermostat but it didnt help very much. my cooling fan DOES kick on. and there is pressure in the system because when i take off the rad. cap it pops when letting out the air. it doesnt overheat during idle so i dont think its the water pump and im not letting out white smoke and my spark plugs arent tinted green so i dont think its a head gasket. could it be a bad overflow bottle letting it suck back in air instead of coolant?

 

[19Eclipse90]

It doesn't suck coolant back into the radiator because there is no coolant left in the overflow?

It sounds like you are perfectly aware of the overflow's purpose, so I won't delve into that unless needed. Though on that note, it seems highly unlikely that the overflow bottle would be the cause of all this simply because it is only a bottle holding a liquid. It has no seals or things of that sort. If the hose connected to the overflow cap running inside the bottle is missing or split and allows air in, that would keep coolant from returning. But my first guess is that air is in the system and you have yet to get it out.

 

[68442]

Hows the seal on your overflow reservoir? On mine the cap is always popping off, going to move it and find a better bottle. You could always hook up a mighty vac to the overflow hose and see if you can pull vacuum or see if its leaking.

 

[19Eclipse90]

Sorry, but that post directly contradicts what I said so I feel like I must justify myself. If the overflow is set up correctly, there will be fluid in it and the hose running from the cap into the fluid. With the hose running straight to the fluid, that "closes" the system meaning anything outside of the hose in the bottle does not matter. The cap connects the hose inside the tank to the hose running to the thermostat housing. Whether or not the cap seals around the bottle is irrelevant and as far as I know there are no seals on the overflow cap.

 

[68442]

Yes I believe you are correct, main thing is the bottle is lower than the thermostat housing and no rips in the hose etc to impede the suction back.

 

[66ss]

just to rule it out id check for a bad head gasket....easy way to do this is start the car with the rad cap off, if it shoots coolant a foot in the air u have a bad head gasket, alil coolant may trickle out on start up thats fine, but if it shots out like its under pressure that no'a good

 

[LiquidX]

I know it was stated already, but did you check for cracks or even replace the hose that goes into the overflow bottle? What pressure rating is on the rad cap and how well does it seal?

You said it's new but when I had an issue like this before it was my rad cap not making a solid seal which would push coolant into the overflow bottle. If you can squeeze the upper pipe and hear/feel water rushing through the line that connects to the overflow bottle then the cap is the culprit as it's not sealing the system and coolant can get to the overfill hole.

Also, what color is the coolant anyway?

 

[mcneilmg]

Ok ive got a 98 tsi and im having a problem with the cooling system. my car overheats every few days if i dont fill it with coolant. the problem is that it overflows into the overflow bottle when it gets hot but when it cools it wont suck it back into the radiator. i changed the rad. cap and the thermostat but it didnt help very much. my cooling fan DOES kick on. and there is pressure in the system because when i take off the rad. cap it pops when letting out the air. it doesnt overheat during idle so i dont think its the water pump and im not letting out white smoke and my spark plugs arent tinted green so i dont think its a head gasket. could it be a bad overflow bottle letting it suck back in air instead of coolant?

Make sure your radiator cap is functioning properly and to do this is with a cooling system pressure tester...maybe your local mechanic. Make sure your hose is not kinked going to your overflow and if there is a check valve make sure thats functioning. Check your lower and upper hose for weaknes. To check out the head situation get a pressure tester.... pump it up to 15 psi and wait for a drop in pressure. Hope this helped

Make sure your radiator cap is functioning properly and to do this is with a cooling system pressure tester...maybe your local mechanic. Make sure your hose is not kinked going to your overflow and if there is a check valve make sure thats functioning. Check your lower and upper hose for weaknes. To check out the head situation get a pressure tester.... pump it up to 15 psi and wait for a drop in pressure. Hope this helped

Spark plugs will mainly appear white with a cooling issue

 

[JusMX141]

Head gasket. When it fails it will begin to push coolant away from the engine from the combustion pressurizing the cooling system.

 

[2g_TalonTSI]

i dont have air in the system ive burped it everytime i fill it up and it pushs the air out like normal so that rules out head gasket and my plugs are normal color. i did notice bubbles coming out of the line that right as it connects to the overflow bottle so im going to replace that line. the coolant is green. and yea i will have to get the cap checked to see if that helps at all.i had a 16psi cap on it and when i went to pick up another one i checked to see what psi it should be at and it came up with a 13psi cap so i changed to that and it still didn fix anything. i hope i have answered to everyone on here!! i do need help on this haha

 

[pur97tsifwd]

You need to figure out why its getting hot and sending fluid to your overflow there is a little hole under the water pump check and see if fluid is coming out if it is your water pump needs replaced. Also make sure your radiator is free of debris and the fins are straight. Also make sure your heat shields are on your manifold that helps keep heat away from the radiator.

 

[JusMX141]

i dont have air in the system ive burped it everytime i fill it up and it pushs the air out like normal so that rules out head gasket and my plugs are normal color.

Obviously you do have air entering the system somewhere if you're burping air out everytime you're refilling the system.

It's not like the coolant that is getting pushed into the recovery tank is getting replaced with more coolant....hell if your car produces coolant, park the damn thing and sell the coolant for profit.

 

[2g_TalonTSI]

ok well i think i figured it out...someone switched my overflow line with the line that runs into the bottle so it would leak coolent out around the edge of the bottle then suck in air from the bottle instead of the coolant. so i switched the lines back to where they should be now i just have to wait and see what happens!!