Mann 900 v8, Low pressure coolant tank and loosing water

[NicholasHill]

Hi there,I am currently delivering a Sunseeker 60, 2008, with 2x MANN v8 900, we are getting coolant tank low pressure warnings followed by low level coolant warning.
Initial thoughts are that the coolant tank cap is leaking, but then where is the water going? We lost 4.5 litres during a 90M trip at 1900 rpm/ 17 kts? We have just pressurised the tank and started the engine in the hope that we could see coolant coming out of the exhaust!
Any ideas greatly appreciated,
Nick

[darylat8750]

If you have a bad head gasket you should either have white exhaust and/or milky looking oil. If you have a bad heat exchanger the water will be just disappearing. A coolant pressure tester will be very useful.

[NicholasHill]

Many thank, no white exhaust but possible coolant coming out of exhaust. So awaiting engineer for coolant tank
Thanks for the advice
NH

[NicholasHill]

Darylat8750,
We got to the bottom of the issue: the coolant stack housing has corroded at the union with the end caps and needs replacing.
Thanks for your advice.
KR
NICK