Overheating 1987 Cherokee

I have replaced the Radiator , the thermostat, and the radiator cap. When on the freeway, runs @ excellent temp.(180-200). When idle or in traffic, runs very hot and overheats with fluid leaking out under cap. Please help. Could a stronger waterpump fix it?

:2cents:

Is the water pump good? Is the thermostate good? Is the cap good? with what you wrote it sounds like something in there is not working right. I would check the termostate again. I have bought bad ones in the past. you can check it by putting it in boiling water. I would also check the water pump but I think you should be looking closer at the thermostate.

Your fan clutch is worn and needs to be replaced. Your electric fan, relay, and temp sensor might need to be replaced as well if the electric fan cant cool the temp down by itself.

You might also need a new o2 sensor. A faulty o2 sensor could be causing the engine to run hotter than normal if the sensor makes the engine run too lean.

My 88 worked that way. Turned out to be poor filling of fluid in the system. if not, water pump is my guess.
It amazed me that I had to remove the upper hose to fill the system with coolant. THe clue was the heater was not blasting heat out when the temp showed nearly red-line.

:2cents:
20 years working for jeep....

Lots of jeeps in with wrong thermostats,,I,E. Original one has bleeder ball in it, aftermarkets do not most of the time..

2nd, as Cmei said filling incorrectly...1990 and prior you must not loosen cap on radiator, ever ! Fill through bottle only.Then comes tricky part..when system seems full run engine and be very carefull and sqeeze what hoses you can to burp out air through the bottle ( have cap off and someone with antifreeze ready to pour it in ). always keep fluid at the half mark in bottle.Most people are amazed just how much air you can get out of that shitty Renault airtight cooling system....
Let us know how you come out....

Snidelywhplsh .Esquire :smokin: