As i have mentioned in other threads, i did my coolant change around 80k miles and the coolant itself looked brand new with not a drop of sediment in it. The radiator core when looking in through the radiator cap looked brand new. I flushed my heater core from the hoses both ways and not a spec of debris came out.

Even though i had bought a flushing chemical i opted not to use it because their was nothing to flush. I cannot imagine that if my cooling system was spotless at 80k that at even 100k it would be in rough shape and require flushing. I would suggest not even bothering to flush it if when you drain it you see no sediment and your radiator is clean. Save your time and money.

Just make sure when you refill the system you use distilled water. It's super cheap and eliminates any issues with mineral deposits.

 

Okay, I'm honestly nothing close to a mechanic so pictures would be greatly helpful. No idea what the heater core even looks like although a mechanic flushed the heater core and showed me the flakes that were clogging it while I looked over his shoulder. Of course, being 5'7", I didn't see much. Could someone post some photos or even a link to a youtube video. (I'll go look on YouTube myself and if I find it, I'll retract this message) Thanks!

 

The heater core is nothing more than a small radiator that sits under your dash. Hot coolant flows through it and your fan blows the hot air into the cabin for heat. The coolant goes in and out through two hoses that go through the firewall. The other end of the hoses connect to the block. You flush it by disconnecting the hoses at the block and holding a tapered hose nozzle to each hose as water runs out the other.

Here is a thread where I flushed mine. It's a Dakota with a 4.7L, but you get the idea. If you are not using pre-mixed coolant, be sure to use distilled water 50/50 when adding the coolant. Tap water is the biggest reason why heater cores clog.

https://dodgeforum.com/forum/2nd-gen...ore-flush.html