Overheating at High Speed (revs) and uphill

[jeDi13]

My Civic ES is also in a similar situation. I recently had its radiator water drained (found out that the previous owner did not put coolant with it) and replaced with a premix coolant. After a couple of week's use, temperature remains normal. Until one night, I decided to gun the vehicle along EDSA SB from Guadalupe to Ayala Ave just for the heck of it. I floored the gas pedal, and the RPM needle went past 5.5K RPM during the downshift to 2nd gear coming from 1.8K RPM * 3rd gear. I sustained the flooring up to 3 seconds only. After driving it for about 3 kms and upon reaching Ayala Ave, I noticed that the temp needle is already at the 3/4 mark. I immediately went to Shell Edsa McKinley and stopped the engine for about 15 mins. Popped up the hood and found that the water reservoir was full and there's no more water in radiator. After filling it up with tap water, I headed back home without a problem.

I used the vehicle again the next day. Temp was normal during the whole travel along Katipunan to C5 with moderate traffic until I reached Bagong Ilong flyover when the temp needle started to go to 3/4 again. Went to the side of the road and stopped the engine for 10 mins. Went to Petron McKinley for a water refill and didn't had any problems again.

After that incident, I decided to drain-replace the water for a few times using distilled water. Used the vehicle after every procedure so that water would circulate. On 4th drain, I decided to add premix coolant. So far, no more rising temp. However, I only had short trips (20 kms in light traffic compared to 20 kms from Katipunan to C5 in moderate traffic) so I can't really say that problem is over.

Any comments on the reason of the rising temp on the two separate occasions? Now I'm starting to think that flooring the pedal was foolish. By the way, both fans are working (just don't know if at normal speed). The water pump's fine too, according to a mechanic as he observed the water in the radiator with the cap taken off while I was revving the engine.