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Crusader 8.1 - 2007: loss of coolant mystery

O

Oshnjoe

New member
We seem to have a real mystery on our hands. We have two of these big boys in our Blackfin Combi . We have had them since new. We have maintained them like you wouldn’t believe. We have replaced more “consumable” parts (both large and small) than there is room here to list. Now the problem: for the last 2 years we have intermittently lost our coolant in one of the engines with zero evidence of where it has gone or why. The engine will maintain its happy running temp of about 165 for weeks on end until all of sudden, while running (we typically run them at about 3,000-3,200) the engine temp shoots up. Sometimes we have caught the rising temp before the alarm went off, sometimes not. After we shut it down and let it cool a bit, we end up having to add approximately 2 gallons of coolant. We have: changed thermostats, had the engine oil tested, and have installed new exchangers. Also there is zero evidence of coolant in the bilge or oil, and no indications of coolant escaping externally from anywhere around/under the engine.

WHERE could it possibly be going and why is the mystery we have yet to solve.

Any 8.1 Crusader folks out there have any experience with this issue?

Has anyone had problems with t-stats hanging up in their rather lame hose seats?

Additionally, what what level in the "degas" bottles do you keep your coolant?

Thanks in advance

 
With new heat exchangers, I'd suspect the elbow/riser gasket, where the blockoff plate is.....

Degas bottle level -usually in between the marks
 
Well... we drained and fully flushed both engines. during that process we found that the pisser hose to the overflow bottle was blocked as well with a ton of crap in both engines. After doing some really intense flushing of the cooling system and ensuring that ALL pathways were clear we also checked the thermostats. we found that we may have not been fully seating the thermos in their housings. When they are fully seated it became readily apparent. as for the pisser hoses to the bottles, we still do not know just what their purpose is, but they are there for a reason. I will say this, since we flushed both engines, properly seated the thermostats and cleared the pisser circuits, we have NOT had any overheating issues OR substantial loss of coolant. Yippee! BTW, We still have no idea where the coolant loss went to but at this point we don't care.
 
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