I have a 02, 4.7lt engine, I have replaced the thermostat (twice), and water pump, and had a back flush done at the dealer along with a pressure test on the cooling system. I am losing a small amount of pressure and having to add coolant every couple of days depending on the weather. I put on about 60 miles per day driving. The dealer was unable to locate any place were the leak is coming from even with the pressure test.
The heater core is not leaking from overflow, I have plenty of heat when using the heater. There is no liquid or foaming in the oil (even changed the oil into a bucket to make sure) the exhaust is not white and does not have any odor of antifreeze in the system. And when the engine is running there is no odor of antifreeze coming from the engine. However it does seem to leak worse when the A/C is being used when it is hot outside, versus just rolling down the windows for some good old fashion 2/55 A/C.
Can anyone give me some direction to go on for locating the leak I am at a loss on where to look next? thank you for any help you can give.

 

id start with a block tester. You may not see the symptons of a blown head gasket or cracked block, doesnt mean its not there. as far as loosing coolant faster with ac off vs on, no connection. for S&S go ahead and replace your radiator cap. $3.00 sadly our daks are cursed with plastic radiator housings. VERY common for them to leak, infact I just put a new radiator in my 01 just over a month ago. Not as much fun when you have added coolers for the tower package in front of the condenser. Anywho back to topic on hand. Id start with new radiator cap and then do a block test on it.

 

I’ve been wanting to go with a custom all aluminum rad I hate those plastic ones had a few just crack open on me and always in the worst place at the worst time.

 

Thank you for the help, I will get a block test done and replace the cap as well. once that is done if I am still having problems I will be back for some additional help.
And for the record I hate the plastic housing in the Radiator as well. Im on the second one and they bite big time.