My nissan serena overheat twice, but the radiator was recently clean and the fan was working well. what seems to be the problem?

thank you very much. upon going to a mechanic, they mentioned that the cylinderhead gasket is the problem and needs to be replaced, but it was already replaced with an original one last november or december last year. is it really necessary to do so? and we did run the engine with the radiator cap open, water suddenly blow up when we try to rev the engine. they said it is the gasket and the cylinder head needs to be rephase, do we have to? thank you very much. upon going to a mechanic, they mentioned that the cylinderhead gasket is the problem and needs to be replaced, but it was already replaced with an original one last november or december last year. is it really necessary to do so? and we did run the engine with the radiator cap open, water suddenly blow up when we try to rev the engine. they said it is the gasket and the cylinder head needs to be rephase, do we have to?

thank you very much. upon going to a mechanic, they mentioned that the cylinderhead gasket is the problem and needs to be replaced, but it was already replaced with an original one last november or december last year. is it really necessary to do so? and we did run the engine with the radiator cap open, water suddenly blow up when we try to rev the engine. they said it is the gasket and the cylinder head needs to be rephase, do we have to thank you very much. upon going to a mechanic, they mentioned that the cylinderhead gasket is the problem and needs to be replaced, but it was already replaced with an original one last november or december last year. is it really necessary to do so? and we did run the engine with the radiator cap open, water suddenly blow up when we try to rev the engine. they said it is the gasket and the cylinder head needs to be rephase, do we have to

The fact that coolant blew out of the radiator when you revved the engine is a good sign you do have a blown head gasket. Other signs of a blown head gasket are white smoke from the exhaust, loss of coolant with no apparent leak, oil level overfull, and a white foamy substance under the oil fill cap. If your head gasket is indeed blown you must have this repaired. If you continue to drive the car in this condition you will destroy the engine. Coolant mixed with the oil will destroy the bearings and rings. So it must be repaired. If you have the head gasket replaced last year then the head was more than likely warped at the time of that repair and should have been machined. I would remove the head and have it checked out by a machine shop and machined or replaced if necessary. You have no choice but to repair this as you cannot continue to drive the car in this condition. The fact that coolant blew out of the radiator when you revved the engine is a good sign you do have a blown head gasket. Other signs of a blown head gasket are white smoke from the exhaust, loss of coolant with no apparent leak, oil level overfull, and a white foamy substance under the oil fill cap. If your head gasket is indeed blown you must have this repaired. If you continue to drive the car in this condition you will destroy the engine. Coolant mixed with the oil will destroy the bearings and rings. So it must be repaired. If you have the head gasket replaced last year then the head was more than likely warped at the time of that repair and should have been machined. I would remove the head and have it checked out by a machine shop and machined or replaced if necessary. You have no choice but to repair this as you cannot continue to drive the car in this condition.