ArkansasCherokee

I'm not very mechanically inclined, but I've been learning more ever since I bought my 93 Cherokee Country. I noticed it overheated over the weekend and it was blowing cold through the vents. I replaced the thermostat and it's still doing it. A couple years ago I replaced the water pump and thermostat so I'm hoping it's not the pump again. Could it be just a clogged coolant system? The fluid looks pretty dirty and I know I haven't flushed it since I bought it nearly 3 years ago. I've heard that I can run simple tap water from my garden hose through it and it should help remove any gunk that has built up. Any suggestions would be greatly appreciated. I don't wish to be blindsided by a mechanic.

dans98xj

I would flush it. Are the hoses that go to the heater core getting hot when it is running? It could be a clogged heater core causing it to overheat. I would also look at the harmonic balance pulley, I have seen them come off an just spin, it happened to my neighbors WJ 4.0 last winter.

ArkansasCherokee

I just replaced the harmonic balancer about a month ago. Or rather I had a professional do it. I noticed it was about to go out.

Firestorm500

Prestone makes an inexpensive kit so that you can flush and back flush with a garden hose. Make sure to pay particular attention to the heater core.

Then fill with 50/50 coolant. You may have to add a little to the overflow bottle until the air gets worked out. This usually takes about 2-3 hot/cold cycles.

If it still overheats, you've got more serious issues than dirty coolant. Actually, dirty coolant alone doesn't cause overheating. If your coolant is actually circulating, it's not going to be a blockage or bad water pump. Even if the heater core is blocked, that won't cause overheating.

A cracked head or blown head gasket will.

gotsnowboards

My problem was clogged radiator. So bad flushing wouldn't help. New radiator with a lower temperature thermostat in Las Vegas, Nevada sure helps.

Firestorm500

Well that's a common fallacy that a lower temp thermostat is better.

Factory MOPAR 195 degree thermostat is best even if you live on the surface of the sun.

gotsnowboards

It works for me and I'm not quite on the surface of the sun.(close though)
I also wired up a manual electric fan too. That helps when I hit it hard.

Firestorm500

You're developing less power and hurting your already abysmal gas mileage with a cold thermostat.

I've been out there in the summer.

gotsnowboards

Eh my Prius doesn't get that good of mileage anyways.

djb383

What/where is the info that says a 195 stat is better than a 180? It's my understanding Chrysler offered a 180 stat thru their dealership parts depts, at least at one time.

All the performance aftermarket stuff (mostly non-XJ that I've seen) offer cooler stats than OE stock claiming better performance. Most of the Ronnie racers out there run cooler stats.

We've been running a 180 for 4 years now in our XJ......it runs like a top, performs well and gets good mpgs.....mid teens city/20+ hwy. Maybe I need to change my thinking but not until I see more solid/sound evidence that hotter is better for all-around good performance. I do understand that a hotter running motor runs a little cleaner exhaust but....most everything I've read also says that extra heat also costs a little in performance.

I also understand there is some give and take on this but I also know that nowhere in the FSM does it say one MUST run a 195 stat or that 210 IS normal operating temp. It does say "do not run without a t-stat".

Firestorm500

I guess the AMC/Jeep/Renault and Chrysler engineers should ask for their money back on their engineering degrees.

Plainly, they didn't know what the heck they were doing when they designed and tested these engines and vehicles.

gotsnowboards

That's helpful. Seemed like a reasonable question. I think if you enlightened us some people would have said, "oh maybe I should switch back to the higher degree." I'm curious besides mileage as to the point of the higher degree t-stat.

Firestorm500

Part of it is emissions related. Many people pooh-pooh this, but at least our air is cleaner than a lot of other countries that don't use emission controls. A cold engine is inefficient in getting as much power as it can out of a unit of gasoline.

The heater works better too. Springtime is coming, but we have seen an inordinate amount of posts saying "I'm freezing!" this cold winter.

red4dr

i think we have all run across things that make us want to find the jeep engineers and kick them in the *****! haha

gotsnowboards

My problem is even with the lower thermostats just driving on the road I'm running 210 and a little below. It gets higher when I hit trails.