Leaking heater cores are pretty common. You are most likely getting condensation dripping from the drain tube but if the heater core was leaking coolant, there is going to be a lot in there yet that hasn't fully washed out. If the level is going down in the reservoir, check other places for a leak such as the bottom of the radiator.

Before you do any repairs, use a digital voltmeter to measure the acidity of the coolant. Place one meter probe on ground and the other one in the coolant. Acidic coolant will generally give a reading of six to eight volts, but even two volts is too much. Flush the cooling system and refill it with new antifreeze when repairs are done. Leaving the old coolant in there will cause another failed heater core in often less than a year.

Answered by caradiodoc (expert)
17,277 answers provided

FOUND THIS "TYPICAL" DIAGRAM OF YOUR RIG IN MITCHELL I

THIS ONE SHOWS TWO HOSES TO THE HEATER CORE, THEY DON'T SEEM TO "TEE" INTO ANYTHING ELSE.

IS YOURS SET UP LIKE THE 1ST DIAGRAM?

I'M SPECULATING THE RED LINE I DREW ON THIS 2ND DIAGRAM DEPICTS THE WAY YOU BYPASSED THE CORE???

OTHER THAN A/C CONDENSATE OR RESIDUAL RADIATOR JUICE STILL REMAINING IN THE CORE, I JUST CAN'T SEE IT LEAKING COOLANT FROM THE COOLING SYSTEM

THE MEDIC

Answered by CJ MEDEVAC (expert)
6,800 answers provided