QuestionI have a 2000 Nissan Frontier with an intermittent overheating issue. Sometimes it will show overheat, other times it will not show any issues no matter how many miles I drive. The engine has 160 miles, I have owned the truck since it was new. I got it with about 15 miles on the odometer.
After having done the work that I have listed below and it after having strange issues with it; I became curious as to whether it was overheating or if I might have an instrumentation problem. The problem has been so perplexing that a mechanic friend was also not sure what to make of it.
Usually if I get on the highway, all is fine. When I get off of the highway, and start onto the back roads, it will start to show overheating. The overheating is always preceded by the engine idle rising before the temp rises. If I stop to take a look, there is no apparent steam coming out or extra coolant in the resivoir. I have replaced the thermostat with a OEM unit, flushed the engine, checked the belt, watched the fan spinning. When I changed the thermostat and flushed the system, I did a thorough cleaning and ran the engine for quite a while with the top hose unhooked with a water hose inserted and the water running until it was coming out of the top radiator opening in a steady stream. I continued to run the engine until there were no more suds or cleaner in the system. I kept a close eye on the coolant gauge while I was doing this.
I have checked the oil thinking that there might be a head gasket issue, but the oil is clean and there is no steam or water coming out of the tail pipe. I have checked the coolant level when the engine is cold and it is good. Under most conditioons, the engine is running really well, it has a steady idle and the gas consumption is normal. The coolant level is not dropping, it is steady. The antifreeze mix is around 50/50. Sometimes when it shows to be overheating, the gauge will suddenly drop to the normal temp, quicker than the thermostat opening to let cool water in. The gauge will go up or down fast or creep up or down. It makes no sense in how it is operating. I have bought but not installed the sensor that goes from the coolant system to the on-board computer. I am also going to open the thermostat housing again to make sure that I have the jiggle pin on the thermostat is pointing up.
The truck was wrecked 3 years ago and the radiator was replaced at that time with a brand new unit.
I originally had a thermostat that would no longer let the engine heat up. In the winter, the truck cab was cold. All the problems started after I replaced the thermostat with a non-OEM unit. That's when I changed to an OEM unit. The problem is not quite as bad with the OEM unit, but it it still there and still perplexing me.
Help!!
AnswerJohn,
A couple of things here. First, if the heater does not work then it is either plugged or has trapped air. I would think trapped air if it were me. I would loosen one of the hoses at the firewall and let the air escape and see if that corrects the problem. On the intermittent overheating problem I would check to see what the true temperature of the engine is with a thermometer or a hand held one that you can point to verify the actual temperature. Also, check the fan to make sure it is operating properly. It is probably not a head gasket unless you are consuming coolant.
