2003 suburban leaking antifreeze. not running hot but i add antifreeze to reservoir about twice a week. leaking at front of engine near center-passenger side.

you have to figure out where the leak is first and u cam add water while running just dont do it when car is hot

The engine can burn alot of coolant before you see any smoke.
And having a cooling leak in the engine could cause it to run hot at times.
If you are adding coolant every week and don't see any leaks, the engine has to be burning it. Most of the time it is a blown head gasket and cracked head or block.

The one definite thing you need to do is to run the engine 'till it begins to leak, turn it off and carefully examine everything and find the source. Obviously, I can't see it but the start of any repair involves identifying what needs to be replaced by looking. Antifreeze will run down to where it can drip off the car onto the ground. Make sure you find the actual source which most often is much higher up on the engine than the point where you actually see the drip. When hot, the coolant is under pressure so before attempting the actual repair wait for it to cool down or you can get burned.

you have most likely blown a head gasket. need to have it inspected and dye tested to make sure. if it is the head gaskets make sure the head is inspected for a crack. hope this helps

You may need to "burp" the system and get the air out. When car has completely cooled, take radiator a off, start car, let it warm up (but not overheat) and see if level drops. Add coolant/water mix to top it off. Never run straight antifreeze. At most a 50/50 mix of distilled water and antifreeze.
Air can get trapped in areas of the system when its been drained. Just monitor that temp and don't risk damaging the engine by overheating.

Through the expansion tank filler, you will need to drain some fluid off first.

DO NOT RUN THE CAR WITH NO WATER,water has to be present in the reservoir to enable the output of heat from the heaters. switch the engine off put water in the reservoir/antifreeze look at the bottom of your engine, see if there is a leak, ifnot fill water on to correct level, close cap, turn engine on, check for leak under the engine, if not when engine reaches optimum temperature, your car should give out heat. after an hour check level of water in reservoir. if it has totally depleted or decreased by a significant amount then, go straight to the mechanic and tell him your observations, it could be your HEAD GASKET, if it is then start saving

check the condition of the reserve tank and the hose from the reserve tank to the radiator for leaks if no leaks there have the Radiator cap presure tested . also this could be a air lock in the engine if the radiator is new with the engine running and the heater on hot observe the fluid level in the radiator with the cap off if it drops as it warms add more coolant this will purge the air .

I guess the burning question is , where is the coolant going.
Is this a 4.3 engine? How many miles does the vehicle have?
Has the intake gasket been changed?
I'm guessing a can of "Bars Leak" may cure your problem.
Let me know.
Regards,

you need to have a pressure check don on the radiator. this will pinpoint the leak if you dont see any leaks externally it could be a head gasket or a manifold gasket but the simplest thing to check is the thermostat. it may stuck in the close position and not letting you antifreeze circulate