Don't mean to be a pest. I just hope you make sure the valve isn't your problem.

 

Where would the valve be? It's a 2000 not a 99, is there still a valve on 2000? Anyway the heat works now, I used prestone radiator flush, the one that says on the bottle "perfect for neglected cooling systems" I found it fitting since the last owner CLEARLY neglected the **** out of anything that had to do with coolant. So anyway, I let that fester in the heating core for like an HOUR and then blew out **** with 100 PSI of air, just like the video showed. It worked, but now the heat comes on and off in my Jeep, not sure why? I think it might just have some air bubbles in it or something? Why would the heat come and go? Also my temp gauge is acting weird, itll go up past idle temp or down, but stay constant, I think it might just be the temp gauge not actually the thermostat or coolant. Anywho, just thought I'd let everyone know that my problem is (half) fixed and I have heat in my Jeep (good heat for only half of the time, no heat r little heat for the other half of the time). Thanks everyone for the help and suggestions!!

 

Ya Know...it may not have a valve. Every car and truck I've owned, including my two Jeeps have one, but I may have seen somewhere Jeep went to just an air flapper deal at some point. It may be your heat is controlled by a vent opened by a vac. diaphragm. Thanks for the info, glad you got at least some heat.

 

The "heater control valve" was on the XJ from 84-96, then discontinued.

 

Why is my heat not constant? Is that just air bubbles? Does anyone know? It was so great yesterday and now today it's kind of poop again

 

Is your thermostat OK? I'm not clear on what you mean by "idle temp...".
You want a 195 degree thermostat. Once the engine is warmed up, it should run at 195 (just under 100C), and stay there. The upper rad hose should stay cold until the engine is fully warmed up.

 

I just changed my thermostat, my temp gauge sometimes reads maybe 20 degrees under or over idle temp (195F for you, 97ish C for me) and I'm not sure why, my t-stat is brand new. I think its just my temperature sensor. I have been having troubls with my cooling system, when I changed my thermostat no coolant came pouring out of the engine ( I just bought this TJ ) and when I went to add coolant andn burp it after I changed my thermostat I added a LOT into the top of the radiator (the fill cap) and then all of a sudden it started bubbling (like air bubbles) and spewing out of the top violently, I've never had that happen before and I have done this on my cherokee quite easily. And on top of that, I then drove it to the car wash, and when I parked at the car wash, there was steam coming from the fill cap and on top of THAT, my heat isnt constant. WHATS GOING ON?

 

Does anyone have any ideas?

 

I say the cooling system is air locked, has a air pocket stuck in it. Best way I have found to fix this is to take heater hose off at core attachment and hold it up higher than engine a bit. Then fill till it runs out hose. Quickly reattach hose and top off radiator. Have heard of a coolant funnel? It attaches to radiator so u can fill it.

 

Yep, sounds like you had/have air in it. When it was "spewing out of the top violently", probably coolant was hitting hot metal and flashing to steam. I haven't tried B Smith's idea, sounds as good as any. Do avoid adding cold water to a hot engine, not good, even for a 4.0!

 

Thanks guys for the feedback, I will definitely try the heater hose idea and my stupid drain plug will have to be replaced like NOW as well, then I should be set for winter! I will follow your guys' ideas and hope for the best! thanks again!

 

I couldnt get the heater hose off the heater core so I just filled by the rad cap and still the same thing happened, it spewed out violently. So I said **** it and filled it and then just went driving. Everything is fine an dandy now, I will fill in the rest tomorrow when its cold. To fix the draincock I just put on an extra rubber washer and screwed it back in lol but it works, now I have heat and no leaks, ready for the winter!!! Thanks for the help from everyone who posted replies, I finally feel good about owning this Jeep!!

 

Glad ya got heat.