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Discussion Starter #1
i feel like i'm beating my head against a brick wall. i keep loosing coolant in my 2003 1.8L, but i can't see where it's going! i fill the reservoir, drive the car, and after a while the coolant light turns on and gives me the warning beeps. I pull over, and let it cool enough to open the reservoir cap, which is then empty, but coolant starts gushing back into it, and it overflows.

My heater core is currently bypassed. i've checked every hose i can see for cracks, wear, and leaks, and see nothing. When i run the car in the driveway until the light turns on, i check and there is no fluid on the ground. i'm not getting any kind of odd-looking exhaust.

i flushed the system twice today, and the water in the system came out clean. i filled it back up, and burped it each time. After driving it for about 20 minutes, the light came back on. i'm getting ready to drive the damned thing off a cliff. Any suggestions would be great...
 

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Do you have misfires when you start the car the 1st time in a day?
Any steam from the exhaust?
Did you bleed the system with the tank raised?

The options are either an air bubble in the engine or an internal leak (head gasket, cracked head). I would do everything to rule out an air bubble before testing for an internal leak.
 

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So it goes from full to an empty overflow tank in 20 miles? Sad to say that sounds like a bad head. You could try to have a shop check for exhaust gases in the coolant. If that comes back positive it's the head for sure. If negative, it still might be the head but I don't know how to prove that.

Was the car ever seriously over-heated or driven for any distance after the STOP message come on?
 

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Discussion Starter #5
The car has only overheated once, and i didn't even let the needle peg the side. It just barely got into the red. And, that only happened yesterday. The issue has been going on for months.

The oil is not milky, nor bubbly.

i bled the system with the reservoir raised.

No steam, smoke, or anything out of the exhaust aside from the normal hot air. No sweet smell to the exhaust. No cloud of any kind.

i'm guessing my next step is to take it to a shop and have them do a leak down test to check for exhaust gasses in my coolant (although i'd expect a white cloud from my exhaust if that were happening...and milky oil), but no shops around me will check it for free, and i'm flat broke, so it'll have to wait until i can afford to get the tester from Harbor Freight, or something.
 

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Since it is only a 1.8T, pull the thermostat and observe what it does when dropped into a pan of water just off the boil. It's free and at least you can rule out that part.
 
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Have you ruled out the infamous coolant temperature flange at the back of the engine?
 

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Have you ruled out the infamous coolant temperature flange at the back of the engine?
That just seems like alot from that flange right? (Unless it just went) But he doesn't smell anything. Only reason I noticed mine was the smell. Coolant level barely changed.

The heater core bypass is in my mind howd you do it?

Just wondering cause of how you have to pull out the heater core hose to bleed air.
 

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Discussion Starter #9
Update: Aside from topping it off again after the reservoir emptied, i drove it around for about an hour yesterday, and had no issues. My wife drove it this morning for about 20 minutes, and the same thing happened again.

The thermostat was recently replaced, as was the housing. Would a bad thermostat cause it to suddenly, and repeatedly lose all fluid in the reservoir?

The heater core was bypassed with a 1:1 connector and some clamps. The inlet and outlet hoses are simply joined together with the connector. When i bled the system, i pulled the heater core hose with the tiny hole back enough to stay connected, but allow me to stick a toothpick through to make sure it was unobstructed. When bleeding the system, i watched the hole for fluid coming out.

i can't really see, or get to the flange at the back of the engine to check it, but if i was losing fluid there, wouldn't there be a puddle on the ground?
 

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A defective thermostat would allow the coolant to boil, but it should show up on the gauge. It's possible that coolant leaking from the flange would hit the exhaust and evaporate, but it does have sweet smell to it.
 

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I suggest you first replace the thermostat. Make sure it is installed the correct way around.
As PZ mentioned, it should show on the gauge, but it would go up fast and might not be noticed.
 

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If you can’t get it to leak while idling in place, there won’t be a puddle. The leak stops when the engine cools and coolant pressure drops.
One diagnostic tool is the diaper. Attach some white paper towels around possible leak sites, and check them for pink coolant after you’ve suffered a loss of coolant accident.
 

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Discussion Starter #13 (Edited)
Took it to a shop and they did a pressure test. It was leaking from around the upper radiator hose connector. Replaced the radiator, and it seems okay now. Will have to test drive it a bit to be sure though. The really weird thing is that while i had the front end apart, i used some degreaser to clean things up a bit. Now when i start/stop the car, there is a grinding noise. Sometimes it's quiet, sometimes it's really loud and i can feel it through the steering wheel/pedals. i think it's the tensioner pulley, but i don't have a stethoscope, and the broomstick it's always accurate...

This part
100807


Edit: It sounds a LOT worse when i close the hood of the car...

Final Edit: It turns out the radiator support bar was rubbing against one of the pulleys. Fixed that, and everything is fine now. Thanks for all your help!
 

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I'm glad it was just the radiator and not the head. My car had a bad radiator which led to a warped head. It acted a lot like yours after it was over-heated a few times. I was always amazed at how fast the temp gauge could move when it got hot. Happy motoring!
 

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i feel like i'm beating my head against a brick wall. i keep loosing coolant in my 2003 1.8L, but i can't see where it's going! i fill the reservoir, drive the car, and after a while the coolant light turns on and gives me the warning beeps. I pull over, and let it cool enough to open the reservoir cap, which is then empty, but coolant starts gushing back into it, and it overflows.

My heater core is currently bypassed. i've checked every hose i can see for cracks, wear, and leaks, and see nothing. When i run the car in the driveway until the light turns on, i check and there is no fluid on the ground. i'm not getting any kind of odd-looking exhaust.

i flushed the system twice today, and the water in the system came out clean. i filled it back up, and burped it each time. After driving it for about 20 minutes, the light came back on. i'm getting ready to drive the damned thing off a cliff. Any suggestions would be great...
Check your oil ..... is it milky brown ?
 
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