2007 Jeep Compass Coolant issues

2007 JEEP COMPASS
171,000 MILES • 2.4L • 4 CYL • 4WD • AUTOMATIC
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FRED912
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Coolant in the rad is disappearing with no signs of external leaks. Reservoir is full. Engine runs hot.
Oct 9, 2015 at 4:45 PM
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CARADIODOC
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All of those symptoms point to a leaking cylinder head gasket. There's two tests that can verify that. One is to perform a chemical test at the radiator. That involves drawing air from the radiator, while the engine is running, through a glass cylinder with two chambers partially-filled with a special dark blue liquid. If combustion gases are present, the liquid will turn bright yellow.

The second test is to add a small bottle of dark purple dye to the coolant, then search a day later with a black light. The dye will show up as a bright yellow stain that you can follow back to the source. If the head gasket is leaking, the dye will be found inside the tail pipe. Auto parts stores will have the dye, and those that rent or borrow tools should have the black light.
Oct 9, 2015 at 5:28 PM