Changed thermostat on 1990 toyota 4 runner v 6 still willnot reach operating temp.
Took coolant block off i n back of motor ,cleaned it out replaced sensors,,replaced thermostat, still willnot reach operating temp for transmission to shift into overdrive.pull on side of road cut off,let sit few minutes ,ok reach normal, few miles down road starts cooling off ,kicks out of o.d. again
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the fan will come on when the coolant temp reaches a preset temperature normally around 85 C
by passing the cooling temp sensor to have the fan running all of the time is a pointless exercise as if the thermostat is not open there is no coolant to cool and if the thermostat is fully open then the fans will be running anyway
what you should be thinking about is finding out why the vehicle is overheating when under load
have the fault codes read first
possible reasons are
at converter blocked
radiator cores blocked
transmission over heating and putting he radiator under stress coolant temp sensor faulty or relay faulty or fuses blown
it could be you have an air lock in the cooling system
remove the rad cap from the rad, start the engine and let it run until the coolant drops (add to fill it back up) or until the coolant boils out of the rad spout.
maybe pull the heat sensor. -replace it OR clean it off, reinstall it.
P0128 - Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature)
This means that the engine's PCM detected that the engine has not reached the required temperature level within a specified amount of time after starting the engine. The intent of the P0128 code is to indicate a faulty thermostat. Similar codes: P0125
In determining the engine did not reach a "normal" temperature, it takes into account the length of time the vehicle has been running, the intake air temperature (IAT) sensor reading, the engine coolant temperature (ECT) sensor reading, and the speed of the vehicle.
Symptoms: You will likely not notice any drivability problems other than the MIL illumination.
Causes: A code P0128 may mean that one or more of the following has happened: * Low engine coolant level * Leaking or stuck open thermostat * Faulty cooling fan (running too much) * Faulty coolant temperature (ECT) sensor * Faulty intake air temperature (IAT) sensor
Possible Solutions: Past experience indicates that the most likely solution is to replace the thermostat. However here are some suggestions on troubleshooting and repairing a P0128 OBD-II code: * Verify coolant strength & level * Verify proper cooling fan operation (check if it's running more than it should). Replace if necessary. * Verify proper engine coolant temperature (ECT) sensor operation, replace if necessary. * Verify proper intake air temperature (IAT) sensor operation, replace if necessary. * If the above items check out good, replace the thermostat * If Nissan vehicle, check for Technical Service Bulletins (TSBs), as the ECM may need to be reprogrammed to correct the P0128 code
Because you have done so many repairs already I would most likely say that the gauge is defective. I would use a manual temp probe and probe the coolant temp after the car has reached operating temp. Coolant will be between 180- 230 degrees. If coolant temp checks out and you can see coolant moving in radiator and the vehicle does not overheat then you will need either a gauge or a coolant sensor. To locate the sensor it should either be mounted in the thermostat goose neck housing or the intake manifold.
The "probable cause" is the "thermostat" is stuck open, not allowing the engine to reach operating temp (190-195f) . As for the sensors, obviously its working, but if its corroded, its leaking and needs to be replaced. Better hope the plug is ok or you will need to replace that also. Replace the thermostat. Stay away from autozone.
more than likely the thermostat has stuck open. Or opening to soon not allowing the car to reach normal operating temperature. I would start by replacing the thermostat. Clearing the code and running a drive cycle and see if the code comes back. if the code does not return problem solved. if it does return replace the coolant temp sensor.
t's a cooling system
malfunction code. Either the car took too long to reach operating temp
(like a stuck thermostat) or is getting bad readings from the temp
sensor. It's the same unit as for the gauge but a different part sends
a signal to the ECM, so the gauge ma read fine.It means more than likely your Coolant Temperature Sensor (CTS) is faulty and reading an incorrect temp. As noted by a few above, replace with the new "green top" version of the sensor, clear the code, and you should be set. You shouldn't need anything else unless the thermostat is sticking open...
U are talking about two different sending units, one is the Engine Coolant Temp sensor, the other is the temp guage sender, sounds like you have a bad thermostat, if the engine doesn't reach the proper operating temp it will set a code for the engine coolant temp sensor, and the guage will not move or move very little, replace your thermostat and both problems will go away.
Hi micro0711, the fan (which I assume is electric) works off of 3 corresponding pieces of equipment: the rad,the thermostat and the coolant temp sensor so if you have a 180 deg thermostat the coolant would circulate through the engine and generate heat once the coolant temp reaches approx 180 deg the thermostat opens the coolant temp sensor signals the fan to engage removing the heat from the radiator cooling surface maintaining a safe operating temp. If you find your temp is rising check to be certain there is power to the fan and also that the thermostsat is operating,hope this helps good luck