Hi all, been a while!

Used to have a '97 DX coupe, but somebody hit it while it was parked outside of my place and it got written off. Long story short I found a good deal on a '98 DX hatch with only 96k miles on it! Only thing that needed replacing was the axles and the temp gauge sending unit. I also noticed the cooling fan wasn't coming on as it should, but did not see any signs of a bad head gasket. (Heater gets hot, no chocolate pudding in the oil, no gunk in the coolant, etc.)

So I bought the fan switch and the ECT sending unit, drained the coolant, installed the parts, and refilled with new coolant. Now the cooling fan comes on as expected and the temp gauge works, but it fluctuates between 1/2 and 3/4. (Yes I bled the cooling system by parking on an incline, squeezing the rad hoses and adding coolant until no more bubbles came out and the cooling fan came on twice.)

So I think I have 2 or 3 possibilities; 1 is the thermostat is not opening when it should and the engine is getting a bit warmer than normal, 2 is the new temp sending unit is bad, (possible because it's not from Honda) and 3 is head gasket.

The thing that I find strange is that the cooling fan only comes on periodically even when the temp sensor starts going toward 3/4. Would it not run all the time until the temp got back down to normal if it was actually overheating?

Any suggestions?

 

The first step is to park on level ground, wait until the engine is cold, then check that the radiator is staying completely full.

Replacing the thermostat anyway should be strongly considered.

 

Ok, if the radiator is not staying completely full, what does that mean?

I am planning on replacing the thermostat this weekend.

 

Radiator not staying full means either a bad cap (going to the reservoir - doubtful), you are leaking, or burning.

I would replace the Tstat as MK suggested and go from there.

 

Ok thanks guys. I will check the rad when I get home.

 

Checked rad, it was completely full up into the neck for the cap.

Does that just leave thermostat then?

 

The other thing that seems strange to me is that the temp gauge rises almost immediately after I start driving. It seems unlikely that the engine can get to operating temp in anywhere near a min or so from start-up.

Thermostat? Sensor? Gauge?

What is the normal operating temp range for the coolant?

 

i do not think the engine is capable of getting to operating temp that fast as you said, regardless if the tstat is staying closed thus i would check the sensors first.

Also consider rebleeding the system and triple checking that it is completely bled of air because that would make it heat up that fast according to the sensor and is a critical part of working with the cooling system.

 

run the car on level ground and check and feel the top radiator hose and see if it there if the top radiator hose is boiling hot and then touch the bottom radiator hose and see if it is cold to the touch this would be a dead give away that the thermostat is stuck closed run the car til it reaches operating temp and fan comes on

 

I have tried doing the bleed procedure 3 times after I refilled everything. (Heater on full hot, parked on incline, squeeze rad hoses until no bubbles come out until engine warms up.) Can't get any bubbles to come out, so I'm pretty sure there is no air in the system unless it's trapped somewhere and can't get out. Are there any bolts or anything I can loosen off to check for air pockets?