A 1997 Honda Mile 3.0L sedan, using V6 engine, mileage has reached more than 20 million km, the recent vehicle in the process of running, the engine has a coolant temperature is too high or even "boil" failure. Due to the driver's negligence, the vehicle in the case of high temperature engine also continue to drive, eventually leading to the vehicle flame and can not continue to drive.
    Dragged back to the factory, the maintenance staff intuitively checked and found the rear of the engine warm water pipe rupture, resulting in a large number of coolant loss, causing the engine coolant temperature is too high, at the same time found that the radiator water pipe is also aging leakage phenomenon. When we want to replace its water pipes, while unplugging the water pipe, found in the coolant out of the light yellow oil and water mixture. General experience tells us that this engine due to high temperature and the driver also continue to drive the vehicle at high temperatures, causing the possibility of damage to the cylinder pad the largest. So the maintenance staff will be left and right side of the engine cylinder head removed, clean up the cooling system of water pipes, cylinder water jacket, cylinder head water jacket and water tank in the oil and water mixture, while replacing the rupture of the two pipes, and other aging Of the warm water pipes are also replaced, fitted with cylinder pad and cylinder head, the engine installed complex. The starting engine is running well. The road test engine coolant temperature is normal, then finished delivery.
    But did not last long, the vehicle in half a month after the factory rework. According to the owner to reflect the car back to the back, did not travel how many miles, only driving more than 500 km, the engine coolant temperature is too high. Into the workshop, the author of the car to check, the engine coolant temperature has reached the "boil" level. With the fault diagnosis instrument PGM detection, the engine coolant temperature between 98 ~ 100 ℃, the engine coolant temperature is indeed high. Through the Mitchell database, got the car cooling fan control circuit diagram, the car fan control circuit for testing, the results are normal. Fan high and low speed normal operation, there is no fan control system circuit caused by the engine coolant temperature is too high fault. So fill the radiator coolant, connected to the PGM fault diagnostic apparatus, climbing road test. During the climbing process, the temperature of the coolant monitored by the PGM is within the normal range, and the fan's high and low speed operation signal is clear. After climbing the top of the hill, open the engine hatch, we found that the fast idle thermosensitive valve seat has a chronic water signs, is not the chronic water leakage caused by the engine coolant temperature is too high? The last maintenance, and did not find this seat There is a phenomenon of chronic seepage, because the fault is always random. Back to the factory, we replaced the fast idle heat valve and related small water pipes. Due to the demolition of the pipe, found in the coolant there are oil and water mixture, may be the last time to replace the cylinder pad, there is no clean up the oil. Fill the cleaning fluid to the radiator several times after cleaning, add antifreeze row of cooling system in the air. By road test, the engine coolant temperature is normal. So once again completed delivery.