Cameron58

1999 Jeep Cherokee Sport, 6 cyl,4L, automatic with air

I have a leaking rad and am going to replace it. I ordered one from Radiator Barn and should have it in a few days. So, I want to do a flush before installing the new rad. I bought one of those kits where you cut one of the heater hoses, put on a T to connect the two ends, connect water hose to the top of the T, and flush. Do I really need this? Can't I just drain the rad, leave the drain open, stick the hose in the filler opening for the rad, run water in, run the car with heater on to flush the core, let the dirty water drain out through the rad drain? And maybe this is a dumb question, but should I flush with the old rad in place or after I install the new one? Thanks.

x91evo

fyi ,
doing a radiator flush on a cherokee is going to take more than one flush to properly clean it. Or a really really long flush haha.
Our motors like to let a bunch of crap build up inside of them!

DFlintstone

DJB is the cool (ing) guy. If he doesn't find you PM him. >>https://www.cherokeeforum.com/search...archid=4165233

I might treat the heater core and the rad separately myself.

Cameron58

Approx. how long is a "really, really" long flush? Not a problem. I'll just start the water running and go have a beer. But, how long in your experience will the water have to run? I know it's different for each car depending on how gunked up it is, but just in general, how long? Thanks.

Cameron58

Thanks for the response. That link doesn't work. Is his user name DJB?

I really don't need to flush the rad since I'm replacing it, but I need to flush everything else. How do I treat the core and the rad seperately?

Cameron58

Can I just remove the old rad, stick the water hose into the radiator hose that connects to the right side of the rad, let the water and gunk run out the radiator hose that connects to the left side of the rad, and let it go until the water runs clear? This will flush the core too, right?

HudsonN

Nope. The heater core isn't connected to the radiator via the upper and lower radiator hoses. The heater core is fed directly from the thermostat housing hose(s).

I don't understand why you'd want to flush with your radiator in. You're putting in a new radiator correct? Pull the old one out, then flush it out. Do not flush once you put the new one in or you're going to put all that gunk in your new radiator.

Flush the heater core by putting a garden hose into one of the heater core hoses and letting it gun until the water that comes out the other hose is clean. Then put the hose in the one that it was just draining from and keep putting it in until the water coming out of the other hose is clean. This is known as a "reverse flush".

Some guys even pour CLR down the hoses and let it sit in the heater core to "un-gunk" it.

Also flush the upper and lower radiator hoses the same way. Clean everything out.

djb383

Remove the old rad, remove the heater hoses from the t-stat cover and water pump. Stick a garden hose in one heater hose and flush. Then stick the garden hose in the heater hose nipple on the stat cover and flush. Do a good flush BEFORE installing the new rad. Keep the antifreeze/coolant fresh.

FWIW, the CLR website says "Do not use in a automotive cooling system". I would include that to mean the heater core.

DFlintstone

Yep, DJB383. And whoops! You are right, bad link.

Some of us were thinking CLR might be a desperate last shot in an, (isolated) plugged, heater core short of changing it. I suppose you might dissolve something nearly through and find out next week that didn't work so well after all!