MD 11C with overheating problem

"Coolant will not circulate th

"Coolant will not circulate through the fresh water system causing the engine to overheat. This fresh water system is the Volvo after market system.

Top end of the engine has a new head gasket. The raw water impeller has been replaced, the heat exchanger has been flushed and pressure tested and the seals have been replaced. There are no coolant leaks in the system or engine, however coolant will leak out of the pressure cap of the coolant bowl.

Somehow air or exhaust gas is getting into the system. Does anyone have any suggestions?"

Do You have a system with belt

Do You have a system with belt driven circulation pump or the one with electric circulation pump?

This has the belt driven circu

This has the belt driven circulation pump.

"Take out the injectors of the

"Take out the injectors of the engine. If one is 'clean' You probably have a cylinder/head leak. Does the collant smell 'exhaust'? If so and there are new head gaskets, the leak may be between the casting of the head and the pre-chamber. If so the head must be changed.
On the other hand if there is just an ower heat situation caused by the coolant not circulating, I suggest You change to an electric circulation pump. Getting parts for the belt driven one might be a problem."

"I had this problem for over 1

"I had this problem for over 10 years and did all of the above to no avail, finally found that the reduction gear is raw water cooled and built up restrictions.

Remove, poor conc HCL in, and flush until free flow. No problems since. Helps to soak enging in phosphoric acid, perhaps annually. Phosphoric is kinder than HCl.

PS I'm a chemist too."