From time to time my car is running hot at idle only, not into the red on the temp gauge but hotter than normal.

I know the fan does come on, but sometimes seems a little late.

Should I just replace the thermo switch on the thermo housing or

Replace the coolant temp sensor, or is that only for the ECU readings.

By the way does anyone know the socket size for the thermo switch on the thermostat housing? Which way do I turn?

 

Have you tried bleeding the system properly? Righty tighty, lefty loosey! Temp sensor is only for your ecu and the indication on your cluster

 

Oxygen sensor socket is what i have used on an EG

 

Yes tried to bleed, it was ok for like 2 weeks, doing it again, just not all the time, it is random.

 

Not the same size as a spark plug socket would it be?

 

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Your car has three temp sensors:
-2-wire thermo switch on thermostat housing; controls the radiator fan
-2-wire ECT sensor below distributor; sends coolant temp signal to ECU
-1-wire temp sending unit below distributor; sends coolant temp signal to cluster gauge

With respect to engine overheating, you only need to concern yourself with the thermo switch.

Have you already replaced the thermostat?

Does the lower radiator hose remain cool when the engine is hot?

 

Did not replace thermostat yet, I was thinking it is mechanical and it fail open or closed right? Plus the temp only goes up at idle not driving if it was a bad thermostat wouldn't it get hot when driving?

I have not checked the the lower rad hose. is it supposed to stay cool?

 

Is the motor losing coolant? If you're losing coolant and the cooling system is getting exhaust gas in it, there's you problem.

Otherwise you're just not bleeding it right. Fill the radiator with the car cold, squeeze the hoses to get air out, start the car and keep adding coolant. You have to get ALL the air out.

 

No losing of coolant. Do you add coolant as it is running?

Last time I bleed it for like 25 mins.

 

Your view of thermostat failure is oversimplified. Also consider gradations of failure between stuck fully open or stuck fully closed.

When the engine is fully warmed up, when the thermostat is open and coolant is allowed to circulate through the radiator, the lower radiator hose should feel hot, though not as hot as the upper radiator hose.

 

Ron big favor do you have a diagram to replace the thermo switch?

Do you know the socket size by any chance?

 

srsly?

what would a diagram even show? just locate the switch and take it out, it's not that hard.

 

Because it has the mm size on it, and I need to go get the socket

 

How often do two of these sensors go bad at one time? I have been having a problem and I am leaning towards replacing both of the 2 wire temp sensors: the ECT switch and ECT sensor. I have intermittent radiator fan problems, where it turns off for no reason after I am driving for a very long time, on the highway for example, and then have to stop and get stuck in stop and go traffic. The car will slowly start overheating because the fan turns off. I have to shut off the car and restart when the traffic moves, etc. It gets annoying. Also, sometimes my car doesn't start... it just sits there when I turn the key and does not even crank at all. I have heard that the ECT sensor can cause bad startup problems, and the first problem with the fan turning off sounds like the thermo switch could fix it. I have replaced the fan relay in the underhood fuse box with OEM from the dealership, and it did not fix the problem. It seemed to fix it for a month or so, though. Any thoughts? I just don't want to replace both of them without knowing which will fix the problem, because they are not that cheap from the dealer.

 

How often? Don't think that data will be readily available do you?
Cars that are pushing 20 years probably need to have everything replaced about this time. Something to consider.

 

No, I didn't expect hard data to be available. It was just used as an introduction to my story. A bit of a brain picker, to be exact. Well you are right, but still, I want to avoid replacing many things at one time. My body is definitely pushing 21 years old actually, but my engine is a 96 with pretty low miles from HMO so I am not quick to believe everything should be replaced right about now.

 

Preventative maintenance. That's all I'm suggesting. And 96 was a ways back. In one short month it'll be 17 years. Even if it was from HMO.

 

I understand. I typically am the first to practice preventive maintenance, but right now I am living on a tight budget. Almost everything else on my engine is within a year old. I would just like a little more opinion on this matter before I buy both sensor/switches. I am just not sure it could be the ECT when it is not throwing an ECU fault code for it. And also when it does start after those no starts, it has no problem running. But there are separate times when there is a hard start.. so I guess its possible.

 

i having issue with coolant system, i replace coolant and thermostat already bleed the air out. but when on the city and stop lights the temperature of the car goes up, the coolant fan comes on but it seems minuts past and then againg like it takes awhile it to come. what could be the proble. what i been reading civic have this issue.

 

Please create your own thread with all the relevant car information.

Please do not necrobump 6 year old threads. Instead add the URL to this thread to your thread as reference.