What is the solution for slight coolant leakage after replacing the cylinder head gasket?
2 Answers
Coolant leakage should be addressed by replacing the hose or re-securing the connection depending on the situation. Coolant replacement method: Drain the old coolant, then flush the liquid channels with clean water. Add clean water to the coolant reservoir, then continue adding water to the reservoir so that it continuously flows through the engine cooling system. Start the engine and let it idle for 3 to 5 minutes to circulate the water. The water initially flowing out from the reservoir will have a faint pink color. Continue adding clean water until the outflowing water runs clear. Note: Don't forget to remove the heater hose to drain the water from the heater core. After approximately 1 hour of draining, add new coolant through the radiator hose - this allows the coolant to flow into the radiator quickly. Then add another container of coolant to the reservoir until it's nearly full. Run the engine for about 10 minutes; as some air is purged from the cooling system, the fluid level will drop. Add more coolant until it reaches the "MAXT" mark on the reservoir.
This is a situation I often encounter, especially with cars just repaired in winter. Last time when I replaced the cylinder head gasket for Old Zhang, he reported coolant leakage on the third day. We immediately disassembled it for re-inspection and found a small scratch on the cylinder block sealing surface that wasn't cleaned properly, with residual old gasket fragments causing poor sealing. It's best to thoroughly clean the mating surface first, carefully scrape it with a dedicated scraper, and ensure the new sealant is applied evenly without interruption. The bolt tightening sequence is particularly crucial - you must follow the manufacturer's specified cross pattern in three stages to reach the standard torque. After replacement, don't rush to drive; let it idle for half an hour to observe any new leakage points. It's best to conduct a 15-minute pressure test on the cooling system to confirm sealing. If you're not confident, return to the repair shop immediately for rework - minor issues left unattended may cause engine damage over time.
