I know there is a thread but it did not help. I have been working on cars for 30 years so I have some idea of what I am doing but this one has got me stumped. The jeep in question is a 91 4 cyl. all stock. After about 10 minutes of driving it red lines. I have replaced the water pump it was just over a year old but changed it anyway (was under warenty). I took both hoses off at the radiator and hooked a water hose to the top hose and ran water though until it was clear water runing through. Then I hooked the water to the bottom and ran water through to make sure there was unobstructed flow. I remove the therostat, the frist thing i did thinking it was not opening, put it in a pan of the stove it is opening all the way. when i take the top hose off and fill the radiator and engine with water and turn the the jeep on the water comes out of the top hose in a surge flow not a constant. Thought maybe then the radiator was bad. so i filled a bucket with water took the bottom hose off put in the bucket still surge flow with by passing the radiator. bottom line it is still getting hot. any idias
Still could be a major part of the radiator is clogged. When its running, all you have to do is put your hands on the radiator fins, if you feel cooler spots, and then say warmer spots in random areas, then its clogged. I have a 3 row all steel core I managed to clog up with stupid stop leak. It looked ok if you opened the cap for a visual..open it up...and gobs of black tar like substance ws clogging it up.
Also are you sure its not the temp sensor is not bad?
I have had two different cars in the past that had so much corrosion in the water jacket of the engine that they would run hot, but neither one ever overheated. One of them would actually boil the water in the jacket after I turned the engine off and I tried everything to fix it. I replaced the radiator, pump, thermostat, etc.
Anyway, the way I fixed them was with muratic acid. If you're interested I will post the procedure.
Had the same EXACT thing happen to me; it was a blown head gasket between cyl #4 and the water jacket. I wasn't getting any water in the oil, and hardly any noticable white smoke on startup. I was loosing about 1/4 gallon every week to two weeks. What makes me say the head gasket is when you said about the backflow out the radiator.