Santa Fe 2002 232K miles. Car losing coolant, especially in summer if A/C is ON. No water in the oil. No apparent leaks. No white smoke from the exhaust. Freezing plugs are OK. New water pump and hea

Pressure test system for external leaks , head gasket or cracked head can produce this symptom. Due to high catalytic converter temps , antifreeze / coolant vaporizes and goes undetected

Remove spark plugs look for traces of green, blue/ red coolant or what looks like very white porcelain colored tips on the plugs usually sign of coolant entering combustion chambers

I've already done that. No visual traces of coolant on spark plugs. Thanks

Leave pressure test on overnite , next day check each cylinder for liquid do not crank engine over while plugs are out , no fluid on next day rules out cracked head only . Head gaskets fail after engine temp rises over 212 degrees or associated boiling point of coolant. Don't be fooled 50-50 delusion is not good enough anymore 70-30 retain 265-270 degrees boiling point

you can purchase a combustion leak test kit for around 45 bucks and there are several youtube vids on how to do it (easy). it is a pretty conclusive test for a bad head gasket.

they sell a color dye that glows with black light to show leaks. sounds like bad head gasket or crack in radiator.

If it is radiator crack why A/C is involved? Coolant goes heavily if A/C is on, mostly in summer time.

Coolant overflow system leak? As the engine coolant heats up, the expansion causes coolant to flow into the overflow container. When the engine cools off, coolant flows back into the radiator. If there is a crack in the line to the overflow container or in the container, there will not be a vacuum to pull coolant back into the radiator.

Just checked everything. No visible leaks.

Thanks for your suggestion

The ac condenser is in front of the radiator, it raises actual engine temp, also pulls 8 to 10 H. P. on engine that requires engine to work harder and hotter.

I've seen head warpage as little as .002 - 003 thousandths of a inch to cause engines to use coolant and eventually run hot

About A/C that is unerstood. Engine is really getting hotter if A/C is ON. But the temparature not rising on the coolant temp gauge on the dashboard. According to the second part your aswer I have a warped endine head, is that correct? By the way, I've replaced the head gasket already. No changes. So the replacement of the engine block head seems to me the only solution. Am I correct? Thanks

If you see no apparent leak its the most reasonable assumption, I would think try removing the thermostat Adding blue devil , it's a special sealer and follow its instructions. It's a liquid glass additive that may prolong the agony of a head removal. Beware though! It can cause heater core problems. Like stopped up core no heat . Like the sign says, enter at your own risk!!!

I do not ever recommend any additives that claim to solve leak problems of any kind in any vehicle system. The do NOT ever work and ALWAYS cause other problems in the systems. May as well stand in front of a fan and piss into it, it's the same result you will get for throwing $$ away on leak fix products and then have to pull it apart and fix it right anyway ! I would suggest you leave the thermostat out and run it that way to see if it makes any difference at all. Best/safest guess is a crack in the block or head, warped head or bad head gasket. Best to pull the heads, have them checked and re-machined at a good machine shop and they will check them for cracks at the same time. You can check the head mating section of the block yourself with a decent metal straight edge and a feeler gauge or by shining a light behind the straight edge as you check it. If you see light thru gaps between the edge and any part of the gap, there is your warpage.