Cherokee gets hot at highway speed

My 89 with the closed system gets hot at highway speed. It also will get warmer at stop lights. I have replaced radiator(shop told me it was not flowing well enough), new antifreeze and flush, thermostat, pressure cap, and have not changed any symptoms. It did quit getting hot over the winter though. I have read many threads that say someone replaced everything in the cooling system then the engine and no luck. I have not seen anything posted about the air conditioner condenser being full enough of junk to block air flow just enough to limit propper cooling. I am thinking of taking radiator out and washing condenser from back and just thought I would ask if anyone had tried this for those cherokees that get hot without a logical explination. Thanks

Did you replace your viscous fan hub? Does your aux fan come on with A/C and with high temp? Is you bottle in good shape (not cracked)? Did you replace hoses, the bottom or return hose should have a spring in it.?

I second what SJX said to replace. The fan clutch does get over looked and if it over 5 eyars old you have a good chance it is bad. Do not even try to test it, most test give false results, just replace.

If you have a second vehicle remove the mechanical fan and take it to the part store. You can remove the fan so you only have to carry the clutch. Compare your fan clutch to the new one. If they are the same height from where it attaches to the engine to the plane where the fan attaches then get it. There are some aftermarket clutches which are too tall and require you to tilt the radiator to install - avoid those.

Sounds like you may of damaged the thermostat, install a new one and buy it at the dealer.

You may not have all the air out of the engine, here is a good site on how to burp the engine http://www.olypen.com/craigh/cooling.htm

Also the plastic cooling pressure bottle can be bad or had a bad "radiator cap" on it. You can get a new bottle form quadratec.com for $20, might be worth it. I'd go by your dealer and pick up a cap, I apid $5 a few years ago but they may of gone up.

I think I'd replace the fan clutch, make sure the electric fan is plugged in, pull the temp sensor to make sure the air is out of the block and install a new "radiator" cap on the pressure bottle. See if that fixed the problem, if it does not then take it back to the shop which put in the radiator, there is an implied warranty once they changed the radiator.

I agree on the need for a spring in the lower radiator hose. Did you get new hoses when they installed the radiator? If you have to buy a lower hose get it at the dealer. It very nice, has the spring and anti-chafe installed. I paid $22 if I recall for the lower and $16 for the upper.

But change the fan clutch and radiator cap then if the problem continues take it to the shop. How they react will help you determine if you continue to be a customer. My XJ running hot like describe is a valid reason to take it back.

I have had the same type of problems. One time I had to replace the water pump and that fixed it. The next time I had to back fush my cooling system. If your oil happens to be old it can do this as well.

Thanks guys, I am sure I will find the problem. I appreciate all the input.

I´ve back washed my radiator (through the fins). Was amazing how much dust, crude and pollen came out on occasion. I do a bit of dirt roading (dust) and mud roading. I periodically remove the grill and shine a strong flash light from the back of the radiator to the front. Because it looks clean from the front, doesn´t mean it´s clean all the way through.
Carefull with the high pressure washers, if you flatten the fins, it´s not gonna help with the air flow.
washing through the fins of the radiator probably isn´t gonna solve your problem, but every little bit helps.
One thing that has givin me grief, is pin hole leaks. A very small leak, that is hardly noticeable, usually just a stain, that doesn´t even drip. Every time the system goes through a cool down cycle, it can pull a little air in through the pin hole leak. It adds up over weeks/months and causes, air block cooling problems, that often sneak up on you.