92 Cherokee Runs Hot

[cmbraith]

Hello Everyone! So, a couple weeks ago I decided to flush my coolant system. The electric fan had stopped working, and so I decided that I would get a new one, and go ahead and flush the radiator/coolant system while I was at it. So, I did. I bought the prestone flush 'n fill kit, and flushed it. Since I live in a desert that reaches 110F quite regularly, I decided to install a thermostat rated at 160F, instead of the stock 195F. While I waited for the new electric cooling fan to come, I drove around w/out one on. I had been doing so for a while anyway, and the jeep was only running slightly warmer than usual.
After the installation of the new thermostat, and the flush the Jeep would get really hot after 10 minutes or so of driving around in 100+ degree heat. When I received the new fan, I installed it and expected things to improve - which they did. The Jeep doesn't get hot unless I've driven 30 minutes or so, and it's stop and go. It's fine on the freeway. I also replaced the heater control valve, as it was leaking.

Here's what I think it may be:

The cooler thermostat doesn't let the coolant sit in the radiator for very long, and diminishes the cooling capabilities of the radiator

When I refilled the coolant system, I accidentally put too much antifreeze, making the ratio about 7 parts antifreeze to 3 parts water.

That's all I can think of. The head gasket is fine.. I haven't noticed any change in the engine, and the oil is not milky at all. No visible leaks anywhere either. Let me know what you think! I'm kinda stumped.

 

[kreatos909]

it may be that you used to much of the flush kit and possibly fried the radiator. did you check your cap to make sure its holding the pressure. did you Burp the system?

 

[MudderChuck]

I've talked with guys using a 180 thermostat and things seem to be fine. Others have said their gas mileage drops after installing a 160, especially in the winter or cool evenings.
I only use distilled water 50/50 mix (or whatever the owners manual recommends). Or test it with a coolant tester to -22F (it gets cold here).
Takes awhile for all the air to work it's way out of the system after a refill. The radiator cap holds pressure to a certain point, then spits air and coolant into the recovery bottle. When the motor is stopped and cools down, the special cap (with a valve) lets the coolant be sucked from the recovery bottle back into the radiator. As your engine purges the air from your recent flush and refill, the coolant level in your recovery bottle should drop when the motor is cold, you may have to add some coolant.
Low speed overheating is often a weak fan clutch.
If you haven't been using distilled water, the inside of your radiator may be (is likely) partially blocked by deposits. Flushing can help, but over the years it builds up to the point the only real solution is a new radiator. It's often bad by the outlet, you can actually look in the radiator outlet (drivers side) with a flashlight and see deposits or use a dental mirror for a real look.
I've reused coolant before, ran it into a clean catch pan, filtered it through a rag or coffee filter. Coolant testers are cheap, drain the coolant, filter it and mix with water using the coolant tester to spec. Remix what you have left over to spec and save it for next time.

 

[cmbraith]

The Jeep is 18 years old, and has been in a desert since it was born -- running in some pretty brutal heat for that long can take it's toll on the cooling system. I burped the system by filling it up through the upper radiator hose, and took the Coolant Temperature sensor out of the back of the engine block. I filled it up until I saw a steady stream of fluid, and than put everything back on. So, I'm doubtful there is any air in the system. Also, my system is the closed system that does not employ a pressurized bottle, so the air pocket problem is not as bothersome as it is with earlier models.

I figure the radiator has a lot of deposits that won't come out with simple flushing. It's old. Now it's starting to cool off here, so I figure I'll wait until next spring to get a new radiator, If I need to. My Jeep has slowly started running cooler, and cooler. It's still 100+ heat here, but it's not getting nearly as hot as it was.

Sometimes, they just need a little time to adjust to things, eh?

Thanks everyone!