Hello everyone.
I have a 1997 Civic Coupe with the D16Y8 and 5spd manual which I have been restoring for the last couple of months.
The engine runs great. No coolant or oil loss after a couple of hundred miles, even did some top speed and hard acceleration.
At first the temp gauge didn't move at all so I found out the 1 wire sensor below the distributor was bad and replaced it with an aftermarket one. However, the temperature gauge is reading very high, even gets to the H mark if I let it idle or do some uphill roads. The fan turns on when the gauge is reading a tick above 3/4 and will turn off a bit later but the gauge keeps on rising. With a thermometer I have checked multiple times each hose, radiator, block, head, thermostat housinf etc and the car im pretty confident the engine is not overheating. The fan is coming on around 90-95 Celcius which seems about right. So far I have changed: Thermostat, coolant (bled correctly multiple times), timing kit (not the water pump because it is OEM and brand new, good impellers and bearings and the coolant flow looks good), OEM radiator cap. I also changed cluster because the fuel gauge was bad but this temp gauge issue is the same. My guess at first was that maybe I got a bad temp sender since it was aftermarket, so I ordered another one from febi (oem Denso is about 100€ so I tried to avoid buying it). With this one from febi I have the same problem. I even wired up a wire directly from the sensor to the cluster (it works with ground), same thing all over again.
My current theory is that these aftermarket sensors are garbage and I have reached out to a friend to try his oem temp sender, but until I can do that im stuck with this. No obd2 port, car is Eudm but I do have a Hondash coming so I can watch live data through the 3 pin diagnostic port.
Does anyone have any guess about this issue and experience with these aftermarket temp senders? I do notice that when I turn my lights on the needle jumps a tick or so. Bad ground maybe? (again, I checked and cleaned every ground I could find in the engine bay and interior)
Please help me guys, I want a somewhat reliable temp gauge and I hate those aftermarket gauges.
Thanks.

 

Update. Tried the OEM temp sending sensor and the issue is solved.

Lesson learned. Always go OEM with these sensors

 

Amen brother. Preach it.