2001 Honda Civic LX 1.7L (not VTEC), MT, 90500 miles. This car has developed a mysterious problem this fall and winter of increasing in temperature on the freeway (i.E. Driven at ~2700 to 3000 rpm at speeds of 60-70 mph). The problem is most noticeable when placing a load on the motor, e.G. Driving uphill in rolling Missouri terrain. Turning the heater on helps alleviate the problem and sends the gauge back to 2/5th's where the engine has always run steadily the previous 90000 miles, including uphill in the summer at speed with the A/C on. I do this when the temperature approaches 3/4 on the guage, or near the top of the temp " icon" on the guage. The ambient temperatures encountered with this problem have been 30-60 deg F so far. I have already replaced the thermostat as a cheap precaution. A radiator flush and fill was performed by a nationwide brand name auto care center at 77000 miles. The current coolant mix has protection down to 20 deg F, meaning with more water it should provide better heat transfer (I think; the relatively high freezing point is a separate problem and will also need to be addressed). Lower and upper hoses are both hot. No sweet smelll or white smoke in exhaust. No coolant loss has been noted, and no appearance of oil or bubbles in coolant when run with the engine warm. Any help/advice would be greatly appreciated, as I am worried about this car overheating in hotter summer months.
Wednesday, January 3rd, 2007 AT 9:25 PM