98 Civic ex mostly stock.
I have been seeing temps near 200° for coolant, with a new OEM thermostat installed.
the thermostat is opening, as both upper and lower radiator hoses get hot.
I’ve tested the cooling fan functionality by jumping with a paper clip, and it runs as expected.
The relay clicks as expected, testing with voltage across the pins.
seems like the ECU is not commanding the fan to turn on (I’d expect anything over 170°?)

thoughts?

 

It turns on somewhere between 197 and 203 degrees at factory settings.

 

ok, good to know. I expected it to be much lower than that. Thanks.

 

Operating temperature is above 177 degrees F.

 

From my experience the fan kicks on at 205F. Rev up the engine in Park or Still and see if the temps rise to 205 and see if the fan starts running. Coolant fan switch could be bad if fan doesn't come on.

 

also, its cold outside, your radiator may not even be getting up to temp to turn on the fan. I havent heard my fan turn on since November

 

I wasn’t aware of a cooling fan switch. Is this one of the sensors? I’ve already replaced both of the cooling system sensors with OEM parts. I believe I’ve just been leary of the temps while driving, and probably over-cautious, but as the engine is running lean, and I haven’t been able to figure out why, it’s making things much hotter than they should be.

 

The sensor/switch you jumped with the paper clip is the coolant fan switch that is on the thermostat housing. If you replaced it and it still isn't turning on the fan there could be an issue with the switch or you have air gaps in the system which could be caused by other issues in the cooling system such as a leak or burning coolant which is common of a head gasket issue. Are you blowing coolant out of the reserve reservoir/tank?

 

ok, thanks for the clarification. I recently replaced the t-stat (OEM Honda), upper and lower radiator hoses, radiator. Unfortunately, the lower hose (Gates) seems to be leaking at the bottom of the radiator. I’ve now got replacement OEM clamps, as I didn’t realize they are one-time-use, and apparently not putting quite enough pressure on that lower hose.
the reservoir tank is not over filling, it’s working as expected, but I am losing a small amount of coolant, due to the leak at the bottom hose. I believe with the testing I’ve done, the components are functioning correctly, and I was just worried about overheating, due to the lean condition I’ve seen on the plugs, and poor engine performance. I appreciate all the feedback about expected behavior of the fan, and cooling system. Once I have a day off I’ll get the replacement OEM Honda lower hose and clamps in place, and hopefully have the leak addressed and the system sealed as it should be.