With Fall and Winter in the horizon, I was considering flushing my heater core at a later date. Besides, after cleaning out the overflow bottle and the new rad, I was in need of some new clean coolant. Because I have just replaced my rad, I really dont want to do a full system flush because I dont want any gunk building in my rad. Is it ok to just pull off the two heater core hoses from the t-stat housing and engine and plug a hose into one and have the other in a bucket? I was also just considering replacing to two hoses after I flushed it anyway. I dont want another snowy winter with medium heat lol. The 4.0 runs at 210.. its about time my heater worked with that heat.

 

That is how I've always did it. Just make sure that you are back flushing it to get all the gunk out.

 

Go for it, but don't use a pressure washer or anything crazy like that.

 

Lol, God I can only imagine. Coolant gunk flying out the end like noone's biz, blowing holes in the core. I was just thinking a hose fitting that goes into a tube to slide in the hose. Water from the hose shouldnt hurt the heater core should it? Also, which hose do I need to hook the hose to for a back flush?

 

Your '91 may have one of those heater core water flow control valves which could be an issue. Any how, our '98 doesn't have that valve so I just disconnected the 5/8" heater hose at the water pump and the 3/4" heater hose at the t-stat housing, stuck the garden hose attachment into the 5/8" hose, stuck the 3/4" hose in a catch bucket and turned on the faucet. Works good and doesn't flush crud from the core into the head/block or rad.

 

If my Jeep has one of those control valves, does that mean I cant do the garden hose flush?

 

Also, where did you get that little attatchment? I really want one. Lol, CherokeeForum is like a bunch of kids that get together and have toys that every other kid sees and wants. Gotta love it.

 

I would think most hardware stores, maybe even an auto parts store has the garden hose attachment. Maybe just temporarily bypass the valve with some 5/8" and 3/4" heater hose to do the core flush. Can't get enough toys, right?

 

So I take it this valve is fairly easy to get to. Thanks for the help!

 

I believe it's under the hood, close to the heater core/fire wall, passenger side. Maybe someone will post a pic.