When i bought my cherokee i didnt notice a radiator leak, couple days later i did. I replaced the radiator and found all kinds of nasty brown copperish colored gunk. flushed the system and thought i was good, i was wrong. Now that its getting cold been running my heater. I dont have good heat at all. Does anyone have any ideas of a way to really clean the whole syst? Any help would be great.

Yea, find the two hoses that go into it. With a garden hose hold the end in your hand to force water through. Go back and forth both ways. Best not to clamp it to house pressure as that might blow it.

Some say CLR is too strong. One guy posted that he put some in, (just his core), for 1/2 hr, then flushed it well. I don't know but that didn't sound unreasonable.