###Help with Crusader 454 overheating##

[Mad Guineau]

Yesterday while fueling my boat up I realized my temperature started climbing up to around 200 degrees. I turned off the engine ans started it up 5 minutes after and it went back to 160. I spoke to my mechanic and he said it could of been a stuck thermostat and he said check the oil and antifreeze, so I did the oil was perfect but the heat exchanger was approx 5 inches low. I have been noticing the level has been going down a little bit but I just figured it was from using the engine a lot. I never have any green tint in the bilge, so I don't know where it has been going. I just had the risers, impeller, and thermostat changed approx 50 hours ago. When I told my mechanic this he said the antifreeze could be going into the cylinders and out the exhaust which makes me very nervous now. The engine has been very smooth with no issues. I have noticed that it is a little tough turning over, so i put in two new batteries. Any help would be great.
Thanks

[seapower]

Yes it could be going into your cylinder's, which case would likely be a bad head gasket. But generally speaking you'd see an overheating issue, because of the combustion gases being introduced to the cooling system. I'd do a pressure test on your cooling system first, to see if you have a crack or hole in your heat exchanger. This is an easy inexpensive "must have" test in my opinion for the issue you have explained. If you come up with a good pressure test, then I'd do a "block test" (this test uses a chemical that will detect a combustion gas leak, from a head gasket). Take it a step at a time. Are your exhaust manifold's "fresh water or raw water" cooled? If fresh water, you could be loosing coolant there aswell. Again that should show up with a proper pressure test. Frank