8th Generation Honda Civic Forum banner
1 - 5 of 5 Posts

·
Registered
2007 Honda Civic Coupe EX
Joined
·
41 Posts
Discussion Starter · #1 ·
During the prime of summer, my temperature reaches, stays, and never went over operating temperature (9 Bars). But during the nights of summer and now going into fall season, it started to go down from 1-3 bars. But it would go back up at a stop/idle or when I accelerate into the higher rpm's and accelerating for sometime.

I have also read threads that this is normal and sometimes this can be due to a broken or stuck open thermostat. Do you think this would have any negative effect for constant flux in temperature even if it has not overheated? Also, is it worth replacing/ fixing the thermostat as this continues. I personally do not think it should not be a problem but I just want a second opinion for this being my first car and still learning about the basic common knowledge.
 

·
Super Moderator
Joined
·
2,448 Posts
Replacing the thermostat is easy. Youtube it, plus, it's cheap insurance. The fluctuation in temp (below the boiling temp) is fine, but realize the engine has to run at operating temp which apparently your motor isn't doing from time to time. See if replacing the stat helps.
 

·
Registered
Joined
·
52 Posts
This is exactly what happened to me: noticed 1-2 bars going down when driving out of the city. It was clearly a stuck open thermostat, at least I was glad it didn't get stuck closed.
Changed the thermostat and the fluid as well since it was never changed anyways. Issue solved, mileage also improved. VERY IMPORTANT: Make sure you mount the thermostat with the small notch facing upwards (you will see in videos what I mean: this ensures small air bubbles can go out even when the thermostat is closed).

Since I didn't find any technical details about the fluid, I couldn't not get any aftermarket replacement and be satisfied with this so I just went with original fluid(Honda Long Life Antifreeze/Coolant Type 2 (P/N OL999-9001)) . Make sure to fill the system up, put the radiator cap LOOSLEY and wait until the fan comes up twice. Top up the coolant in the radiator again and then securely tighten the cap. This is how you make sure you got as many air bubbles out of the system as always.
 

·
Registered
2007 Honda Civic Coupe EX
Joined
·
41 Posts
Discussion Starter · #4 ·
Even though this thread is old, I just don't feel like making a new one.

I still have not replaced my thermostat but I did change my coolant. It still fluctuates but as long as it doesn't overheat right?

My question is that is it okay to keep driving it cool long-term? I rather not go through the trouble of replacing it unless it didn't get up to operating temp at all. It still reaches if I drive for at least 8-10 minutes. I really see it being a problem in the winter if I just wanted to heat up my car at idle because it doesn't warm up until I drive. I also change the oil every 3.5-4k just to avoid condensation from the car being cool at times. Comments would be greatly appreciated!
 

·
Super Moderator
Joined
·
2,448 Posts
Changing the thermostat is relatively easy to do in our cars. I would totally do it. Having the engine running "cool" isn't a good idea. Running rich all the time isn't good for the engine. Get OEM parts if ya can.
 
1 - 5 of 5 Posts
Top