Could it be the relay? My AP2 is at 7-8 bars after being fully warmed up. Is this too high?

 

i believe 7-bars on the temperature gauge is norm for the AP2 (equivilant to 3 on the AP1).

the cooling fan should ONLY turn on if the thermostat is wide open which will only occur if you are sitting at idle for a long period of time.

 

I had a faulty radiator temp. sensor in an old Civic, when the car would start to overheat I would turn the AC on to kick on both fans.

Here is what I know:

00-03 AP1 cars use a radiator fan switch which controls the radiator fan relay. The switch is set to fully close at 199 F. Thermostat fully opens at 194F.

I'm pretty sure that's how it works up until MY 2005.

***I think this info is correct, I would love for someone to tell me if I am wrong***

On 2006+ cars, the ECM controls the radiator fan via input from the Engine Coolant Temp sensor located on the radiator. However, from looking at the wiring diagram, I am unsure how the radiator and condenser cooling fans are controlled independently.

Hopefully that helps and hopefully someone can help me out.

 

After switching to an aftermarket radiator, my fans would never turn on unless I was using the A/C, after some testing I realized the coolant in the radiator never got hot enough at standing idle to hit 199 F needed to trip the fans.

 

So perhaps everything is normal? Here's the thing though. Even at 7-8 bars, after driving the car hard steam would leak out of the coolant overflow tank. Perhaps this is also because I ran straight distilled water with water wetter. I thought this was okay in SoCal I put in a 70/30 mix as of yesterday, but I haven't driven the car hard enough to see if the problem persists.

 

on my scangauge i see that cooling fan comes on at 96 degr celcius.
on rolling it's rare that it gets that hot.
but in trafic or just idling it's definitely does.
so if your fan doesn't come on at idling it's probably not OK.
temp gauge stays on 7-8 bars for very wide temp range.

 

hMm... if there is steam coming out of the overflow tank i think thats a problem. are you consistently losing coolant? steam = coolant boiling.

 

The radiator will drain extra fluid to the overflow tank, then suck it back in during the heating / cooling cycle. That's normal operation. Running straight distilled water with water wetter in theory will allow for better heat transfer but yeah, the boiling point sucks and you'd need a higher bar radiator cap. I believe anti-freeze raises the boiling point, lowers the freezing point, and is an anti-corrosive. The trade off is that the thermal efficiency of the liquid is lowered.

 

I can confirm that after adding the 70/30 mix that my temps stay down. It appears that at the stock cooling system pressure, straight distilled water gets hot enough to boil. I might have to purchase a higher bar radiator cap to help aide in keeping the coolant in liquid form. Has anybody else ran straight distilled water, but had no issues?

Still not sure why the fans won't come on though. Times like this make me wish I had a coolant temp sensor.

 

FYI if you run straight water you'll get galvanic corrosion where the copper starts eating the aluminum. I don't think there's that much copper in the engine but if there is, yeah you'll screw a lot of crap up over time.