'98 Civic EX overheating
#1
'98 Civic EX overheating
Ok, so I've been dealing with this issue for a couple of weeks, which is brought me here. It seems to only overheat from a standstill, though if it's hot enough out, it will do it on a long drive as well. There are no leaks, no white smoke, and no sputtering, so I've pretty much ruled out a bad head gasket. However, I have replaced the hoses, the radiator, and the thermostat and still it overheats. Coolant is topped and I've bled the system to the best of my ability (though whether running the engine on an incline with the radiator cap off is the proper way or not, I leave you to decide). I have noticed that the cooling fan does not seem to come on until the engine is almost in the red. Tonight, I swapped the cooling fan relay with the A/C fan relay and the A/C fan still comes on when it's supposed to, so I think the relay is ok.
As I said, there are no leaks and I'm not losing coolant, so I don't think the water pump is at fault. Also, the coolant coming out of the engine leaves the hose hot to the touch, while the one coming out of the radiator is pretty cool, so I'm confident there is proper flow.
The only thing I haven't checked (and I have purchased the part) is the fan temp switch in the thermostat housing. That's my next step and if that doesn't work, I'm nearly out of ideas. Could it be the coolant temp sensor, or the ECT sender? How likely is that and is there an easy way to test?
This is making me crazy, but for a first project, I'm learning a lot about our cars, so that's good.
As I said, there are no leaks and I'm not losing coolant, so I don't think the water pump is at fault. Also, the coolant coming out of the engine leaves the hose hot to the touch, while the one coming out of the radiator is pretty cool, so I'm confident there is proper flow.
The only thing I haven't checked (and I have purchased the part) is the fan temp switch in the thermostat housing. That's my next step and if that doesn't work, I'm nearly out of ideas. Could it be the coolant temp sensor, or the ECT sender? How likely is that and is there an easy way to test?
This is making me crazy, but for a first project, I'm learning a lot about our cars, so that's good.
Last edited by Ruenin; 08-18-2009 at 03:06 PM.
#2
ya i would bet that its the temp switch. but then again with cooling systems they are a pain. could be a million things (literally) have you checked for power and ground? could maybe be a bad wire connection somewhere. but i would almost bet that its the temp swtich.
#3
I just ran the temp up to about 80% and the fan never came on. I assume that it's either the fan switch or the fan motor. I just took the radiator out to replace it. I seriously hope I don't have to do that again, lol.
#5
I would find the root problem, I had a similar problem where mine would redline then go back down and gauge would not register anything steadily. It turned out the the Temp sending unit (8 dollars at autozone) was bad. Is it actually overheating and shutting off? could the guage just be bad? Not sure just trying to help trust me bro I know how frustrating cooling systems are!
#7
Car has never shut down from overheating. I just shut it off before it gets too dangerous. Anyone know what size the bolt is on the fan sensor? I tried 18mm and it was too small. Looks like 20-22mm but I can't tell for sure. I suppose I could take the thermostat housing off again to get to it....
#8
Don't modify the wiring. The system works great stock as long as all the parts are OK. Find the problem and fix it right. The fan motor life will be shortened by running it all the time, and it is a rather expensive part.
Unplug the temp switch and put a jumper in the plug. The fan should now come on as soon as you turn the key on and run all the time. If the fan doesn't work, troubleshoot the circuit (fan motor, relay, and fuse)
If the fan does come on and run, test drive with the jumper in place to see if there is any overheating. If it doesn't overheat, replace the thermal switch. If it does overheat, verify that the fan did indeed stay running.
Unplug the temp switch and put a jumper in the plug. The fan should now come on as soon as you turn the key on and run all the time. If the fan doesn't work, troubleshoot the circuit (fan motor, relay, and fuse)
If the fan does come on and run, test drive with the jumper in place to see if there is any overheating. If it doesn't overheat, replace the thermal switch. If it does overheat, verify that the fan did indeed stay running.
#9
I would not follow his advice.
#10
I'm gonna try that just to see if the fan motor still works. At least that way I know that it's either the fan or the fan switch. I still think it could be the coolant temp sensor or the ECT sender. Either way, I'm sure it will be the last possible thing I can replace just to make sure I spend as much time and money on it as possible, lol.