New heater core filling up with sludge in Jeep XJ

Was the Cooling system Reverse- flushed completely before adding coolant? How long does it take before it clogs up again? Get some answers to these questions and I might be able to help you better.

Yes it was drained and reverse flushed with a hose. Then chemical cleaner was added, ran that through, and then flushed again after a while per instructions then finally the coolant was added. I don't have an exact time span of when it clogs it. It was blowing out 140f air but now it's much lower, below 120f, and it's really cold lately in the North East so that doesn't help.

Bars leak was used a few years ago when I had a bad heater core. I thought the bars leak would've been flushed out by now. Do you think it's still in the radiator and clogging up my heater core? The water runs clean even when flushing with hose. Except when driving for a while, maybe few days, it'll start to clog again.

I do not see any oil in the tank, so that's 1 down. Nothing else is leaking from the engine bay, so that's 2 down. Guess I need a proper flush from a pro shop.

Ok thank you tennisshoes and finlander for the answers. Last thing, if I have a bad head gasket, would that affect the heater core or heating system at all?

Ok. So it sounds like although that's a serious issue in itself, it wouldn't cause clogging or oil or rust etc to enter the coolant > radiator > heater core.

Just wanted to rule that out. (otherwise I could reverse flush til I'm blue in the face and it won't help)

the heater may be ok , when its flushed if water flows rather full ,your ok and go to heater controls or a fresh thermostat

Some engines have drains near bottom of block left over from casting and have threaded drain plug that can be taken out to allow some of the thick stuff completely out of the engine, The bars leak is also designed to stick to gaskets which also means it sticks to hose's too, I would pull them off to see if the inner walls of hoses are gunked up and if so replace them before power flushing to avoid more sludge introduced to places in the cooling system & remove overflow/fill and clean it out & do the same for thermostat & housing & have the radiator rodded out, I fthe gunk is stuck to plastic side bowls on radiator remove them and clean and reinstall or replace.