I have a 2000 Honda Civic si with a full gsr swap ( b18c). When driving for awhile the temp gauge rises a bit but never reaches the H. Then it comes back down... I checked to see if the motor is hot and it seems to be running cool. I also have terrible gas mileage, the car seems to also run alittle rich blowing black smoke when you accelerate hard. Is it possible for the problem to be the coolant temp sensor or maybe the coolant temp sending unit? I’ve also replaced the radiator, and thermostat. Please help.

 

I think it’s the gauge. They had problems.

 

Yeah that’s what I was thinking, because I can turn it off for a few minutes and then drive again without overheating. Should I think about getting an aftermarket temp gauge and mount it somewhere in the car?

 

I would suggest investigating your gauge, the wire going to your gauge and the sensor provider your gauge the data.

 

Turn key OFF.

Unplug the 1-wire temp sensor under the distributor.

Ground the wire in the disconnected plug to the engine.

Turn key to ON(II).

Does temp gauge needle slowly rise all the way to HOT?

 

I’ll definitely try that when I get off work, also when first starting it acts like it’s getting to much fuel and kinda feels like it’s flooded. Then after a few seconds clears up and idles fine. Any ideas?

 

Focus on the temp sending unit test first. The car may have more than one problem.

 

good point

 

Make sure that you only turn the key on for just long enough to verify proper operation. I’ve read that it can be damaging to the temp gauge to leave it pegged out for too long.