5.0 Overheating

dan313

Active Member
Sep 27, 2009
246
Long Island
Boat Info
2005 270 Amberjack
Engines
350 Mag Bravo3
Good Morning,

This is a friends boat. I have researched this and have not come up with an answer as to why this engine is overheating. The engine is a 5.0 2003 merc used in salt water. The mechanic thought the water pump was failing so it was changed along with the thermostat. The boat still over heated and now the manifolds and risers were changed as of yesterday. We took the boat for a bay test and the temp slowly rose to 196 degs. We were running at 3500 rpms. Dropped it back down to idle and the temp quickly dropped to 158. Got back to the dock and checked the motor. No leaks. I know some of you have had this issue. What was the fix?

Thanks,
 
Could be an obstruction. Backflush the entire system, coolers, hoses.
Circulating pump shot
Block filled with sand from groundings
excessive corrosion in block and heads.
 

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