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My wife has a 2005 PT Cruiser that she loves. Its got 113000km on it . Very low mileage.
I fill the overflow bottle to full cold . 1- 3 weeks later its empty, but the radiator remains full. Ive topped the bottle up 2 or 3 times. Same thing. I decided to leave it and monitor it to see if the rad goes any lower . After 6 months still nothing in the bottle but the rad remains full. Ive had it into a garage. They put dye in the antifreeze and ran a light over it a week later , no leaks. Oil is clean and nothing coming out exhaust. Any ideas or suggestions. Any help or advice would be greatly appreciated.
 

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Welcome to Allpar. Coolant leaks can be intermittent. At 16 years old, it should have had at least one coolant service so far. Is it the correct HOAT coolant in a 50/50 mixture with soft or distilled water meeting Chrysler MS-9769?

A failing head gasket will usually push coolant into the bottle. Coolant may never enter the crankcase and mix with oil or be visible out the tailpipe. Testing coolant for CO2 (combustion gases) content is an accurate indicator of a failing head gasket.

Simply unseating and reseating a radiator cap may seal a leak, especially if there is scum floating on top of the coolant.
External engine leaks may evaporate before reaching the ground. Chalky witness streaks may be left behind.


 
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Discussion Starter · #3 ·
Welcome to Allpar. Coolant leaks can be intermittent. At 16 years old, it should have had at least one coolant service so far. Is it the correct HOAT coolant in a 50/50 mixture with soft or distilled water meeting Chrysler MS-9769?

A failing head gasket will usually push coolant into the bottle. Coolant may never enter the crankcase and mix with oil or be visible out the tailpipe. Testing coolant for CO2 (combustion gases) content is an accurate indicator of a failing head gasket.

Simply unseating and reseating a radiator cap may seal a leak, especially if there is scum floating on top of the coolant.
External engine leaks may evaporate before reaching the ground. Chalky witness streaks may be left behind.


Thats the thing. Its not pushing it to the overflow bottle. The overflow bottle empties a few days after i top ot off but the rad never goes down. Temp goes to 3:00 0'clock on the guages and never moves. Its always been like that. It has never overheated. There is die in the system so im taking it in after work to see if they can find any leak.
 

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That shows that the radiator cap is working correctly. As the engine warms and expands, it will push coolant into the overflow bottle. As it cools and contracts after shutting it off, the radiator will draw coolant back in from the overflow bottle.
If it has to replenish lost coolant, the coolant level in the overflow reservoir will drop, but the radiator will remain full.
Some of the water content of the coolant is lost to evaporation and will drop the level in the reservoir over time, but not to the degree you are describing. It does sound like a leak somewhere.
 
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. . . My wife has a 2005 PT Cruiser that she loves. Its got 113000km on it . Very low mileage. I fill the overflow bottle to full cold . 1- 3 weeks later its empty, but the radiator remains full. Ive topped the bottle up 2 or 3 times. . . .
Maybe the plastic container tank has a crack such that it only opens under heat from the engine compartment while running? Remove the tank, add boiling water and check for leaks. Check hose connection at nipple under the tank. See attached image.

Coolant Recovery Container.gif
 

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Do you ever smell hot coolant outside the car after driving awhile?
 

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Maybe the plastic container tank has a crack such that it only opens under heat from the engine compartment while running? Remove the tank, add boiling water and check for leaks. Check hose connection at nipple under the tank. See attached image.

View attachment 81682
Good point. Those hoses do fail eventually and the PT has a hot engine bay.
 

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Adding additional dye was a good idea. All antifreeze does have some dye (that's the color in it), but leak will be easier to spot with more dye. I don't recall that anyone had mentioned checking the A/C condensor drain for dye to see if the heater core was leaking.
 

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Adding additional dye was a good idea. All antifreeze does have some dye (that's the color in it), but leak will be easier to spot with more dye. I don't recall that anyone had mentioned checking the A/C condensor drain for dye to see if the heater core was leaking.
I would think you'd smell the coolant and a wet spot on the floor if it was the heater core?? Water pump weep hole??? Only leaking under pressure???
 

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Leak in the hoses under the hood only under full temperature/while going down road? Seems like this would be evident after hot shutdown. Might not be a bad idea to ID all under hood water hoses and replace them.
 

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Leak in the hoses under the hood only under full temperature/while going down road? Seems like this would be evident after hot shutdown. Might not be a bad idea to ID all under hood water hoses and replace them.
I just went through a slow loss of coolant in my 04 PT. The source wasn't evident until recently when I could see coolant sprayed around the engine compartment after a long drive the other day. It was the 5/8" hose (4" in length) from the water pump to the metal tubing leading to the heater core. This is located in the front of the engine, under the lower intake manifold. It is very difficult to see.
 
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