memsiej

Bought a beater Cherokee- blows luke warm air when at full blast even after running for 30 minutes. I know it's due for a radiator flush. Will this help with the heater?

fijicorey25

Maybe. The best thing to do is a heater core flush. Start here:

https://www.google.com/webhp?sourcei...rokeeforum.com

Fred/N0AZZ

Do both then replace the thermostat and a new radiator cap.

robertj

I would also add that a 195 degree Mopar thermostat would be best.

Dumajones

I would go with everything those three gents said right there ^^^^^^^^

'00 XJ

If the heater core is going south, be careful. They can make a real mess when they go. On some vehicles they spray coolant or dump it into the passenger compartment, bad if it gets in your lungs.

memsiej

Happened to my last vehicle, a 92 Sonoma. Leaked all over the passenger side.

'00 XJ

Yikes, me too. Shocking when it happens. What a drag.

Charlie Foxtrot

A little info about the jeep might help. What engine? Is it closed or open loop system? How old (what year) is the jeep & how many miles on it? What's the coolant look like? Is it full? Have you tried bleeding the system? What's the temp at the t-stat housing after it's been running 15-20 minutes? (use IR gun aimed at the housing) While the engine is running whats the temp of the two heater hoses? Is one a lot colder than the other? Is your heater valve opening? Is the valve broken internally? There is a lot more to heater & cooling system problems & figuring out where the problem lies. Let's take a professional approach to the issue, and try gathering some info, then we can do a little bit of testing & then we can make a good recommendation on how to proceed.

BillyBoy

I'm thinking a flush and change of the entire system should be a part of everyone's maintenance routine. Every once in a while anyway. ..

What I've learned through my experience is flushing the whole system is better than just the heater box. The reason I say this is that if someone added stop leak, or you have some sludge buildup in your heater box, that might be stopping some leaks. It's not uncommon to hear guys flushing it out and then having to rip apart the dash for a heater box change out. I'd rather increase the life of my engine, and slowly let that stuff flush out by changing the whole systems fluid. Also, it should gradually increase the heat as it cleans.

Good luck.

ANZAC

I have a 99 XJ with lukewarm heat.

I haven't flushed the heater core yet (no leaks inside for the record), but I also saw mention that the heater hose outlet from the water pump can gunk up at the water pump housing.

Cooling system works fine, so I am not inclined to touch the thermostat, but I have 111,000 miles so thinking maybe I should change out the water pump and heater outlet fitting at the same time.

Thoughts?

rgr4475

If you're going to change the water pump, change the thermostat too while you are there. Mopar 195 degree. No reason not to.

ANZAC

Oh, just remembered I replaced it when I replaced the hoses and radiator.

Anyway, back to the heater core and water pump...?