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recently bought 2001 3700 martinique wellcraft with twin 7.4…

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recently bought 2001 3700 martinique...
recently bought 2001 3700 martinique wellcraft with twin 7.4 454 mag mercruiser horizon engines. cruised once for several hours without problems. engine of concern had good power, idled fine and run at about 175-180 degrees. when pulling into marina at 3600 rpm's engine abruptly died. no overheating at that time. shade-tree mechanic put new... Read full answer
recently bought 2001 3700 martinique wellcraft with twin 7.4 454 mag mercruiser horizon engines. cruised once for several hours without problems. engine of concern had good power, idled fine and run at about 175-180 degrees. when pulling into marina at 3600 rpm's engine abruptly died. no overheating at that time. shade-tree mechanic put new fuel relay/fuse in and replaced one fuel injector.(plug had broken of injector)

after repair, engine would no longer idle(race up and down) mechanic said air intake was black inside so he put some kind of fuel injector cleaner in gas and it would hopefully idle again. boat ran at 3600 rpm for 3 min and began to overheat - 215 degress and lost power. i shut it down and let it cool. next day, noted coolant was low, topped it off and burpped. ran boat again. had good power but started to get hot again, coolant keeps dropping. after warming up notice bubbles in coolant expansion tank, leak test went from blue to green. what now
Submitted: 9 years ago.Category: Boat
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Answered in 9 hours by:
9/2/2009
Marine Mechanic: Jeremy R., MarineTechnician replied 9 years ago
Jeremy R.
Jeremy R., MarineTechnician
Category: Boat
Satisfied Customers: 9,020
Experience: Multiple factory certifications 20+ years of experience.
Verified
Welcome to JA

sounds like when she overheat, she burnt some gaskets

pressure check the coolant system with a auto radiator tester
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Customer reply replied 9 years ago
is there a way to narrow leak to manifold, head gasket or cracked block with pressure test? mercruiser mechanic on phone said they wouldn't mess with all that, but typically just put a new block in all the time. is this standard and neccessary if I can localize leak to gasket?
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