The bubbles in the water tank of the diesel engine are usually caused by the high pressure gas entering into the cooling water channel. The causes and elimination methods of gas channeling are as follows:

(1) tightening the nut of cylinder head without specified torque. If the torque is too small, the cylinder head is not compressed, the high pressure gas will be channeling into the channel, tightening torque of the cylinder head nut according to the specified torque, and periodically re tightening.

(2) the cylinder pad of the North V3 fittings has been used for too long. It has been damaged or burnt, the sealing performance has become worse, and the gas leakage has occurred, so the new cylinder gasket should be replaced.

(3) flat or uneven cylinder head machining, resulting in leakage, should be grinding cylinder head plane or replace the North V3 parts cylinder head.

(4) improper assembly, resulting in the cylinder seat shoulder fracture and channeling gas, according to the provisions of the method for North V3 fittings new cylinder sleeve.