Knocking sound on acceleration when the heater gauge reaches quarter
There is a knocking sound when accelerating and the temperature gauge is on quarter, car not overheating. Already replaced coolant bottle cap.
The knocking is usually a rod bearing in the engine. As the engine warms up the oil is thinning out, the oil pressure drops. Have the oil pressure checked with a mechanical gauge to verify if the engine has the proper oil pressure when the engine is warmed up, while the engine is knocking.