Heater core problem F150

Ford dealership is having problems with heater core repair. 2002 Ford F150 Supercrew. Problem is antifreeze (or early on just smell) in the cabin. 4 heater core replacements in 2 years. A hose (?) replaced. Electrolysis kit replaced. 4th heater core replacment finished yesterday. I know that I need to let the dripped antifreeze work out of the system, but I am smelling mild antifreeze this AM. Usually gets worse over 2-3 days then I have to take it in. Anyone know what might be being missed here?

Whatever device your truck uses to regulate the flow to the heater core may be leaking.

Did it get on the carpet? Can you access the core from the cabin? I had a core leak and I put baking soda on the carpet and let it soak it up then vacuumed it up and repeated until it was gone. If it is in the core housing and you can access it then squirt solvent and soak it up with a rag. I don’t understand the number of cores that are being replaced. The system must be over pressurizing and blowing out the cheap cores. Has the radiator cap been replaced?

Just where is the leak ?
That is the un-answered piece of the puzzle.
Have the o-rings been replaced in the hose end fitting that clips to the tubes at the heater core ?
Has a leak detector dye been used to determine the leak ?
They could be ‘‘pissin in the wind’’ replacing cores when the leak is elsewhere .

– I’ve seen a pin hole leak either in a tube , hose , or fitting that sprays a hairline thin, barely visible, only under pressure stream, off to ‘‘over there’’ and the diag tends to focus on wher the DRIP is and not following back to the source
– or –
they could be damaging each core with improper installation. I’ve seen it happen as the person attempts to attach the hoses , they tend to wiggle it or twist it on and THAT action cracks the weld where the tube meets the core.

Are you sure it is antifreeze? my 2k had a tsb about oil leaking from the head gasket due to millings and imperfections. No recall so we rigged an oil drip diversion onto the manifold so I could make long mile drives without watery eyes and the windows open.

Thank you for all of these comments. I will verify the o-rings. I will ask about installation. I don’t know if dye has been used. Will ask. . Radiator cap not replaced. So if the cap were defective and pressure ran up, it could blow out the core?
So far I have used the dealership and they have been helpful but still trouble. As a second opinion, who would you go to?