Onan cooling problem

[nmit5903]

Having problem with a 5.5kva 2006 model Onan. Gathered from former owner all worked OK, recently serviced - heat exchanger serviced, coolant side of cooling system flushed through, impeller and belts changed - service engineers who have been doing this for 20 years cannot get coolant to circulate! Looked at all the obvious things again, impeller, thermostat, blockages incl mechanics cloths - run out of ideas. Any thoughts really appreciated please.

[nmit5903]

After much time and effort the service people found the fresh water cooling system was partially blocked with a white jelly like substance. Never seen it before however I do recall seeing a post, which I can't find. Any takers?

[nmit5903]

Head off and packed with jelly like substance resulting no doubt from:
1. Salt water contamination of coolant system;
2. Some corrosion to head as result of salt/aluminium;
3. Different coolants used over years of cruising in distant parts; and
4. Overheating.
Have since seen threads referring to what can happen to coolants containing silicates in these sorts of situations.
No more updates. Hope it's helpful to someone at some time.