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43 overheat numerous solutions tried

J

jim_mt

New member
"91 4.3 omc - runs at 160 with

"91 4.3 omc - runs at 160 with muff. On water will start to overheat going to 200 and would keep rising.

new impeller, new uptake, new thermostat, new water pump - distributor tried. They have also checked head gaskets and replaced. Mechanic thinks small crack in block that causes pressure and reason for water not circulating and wants to replace block, rebuild engine.

Are there other things that should be checked at this point? Is there anyway to measure amount of water/pressure that should be coming up intake hose to thermostat at idle?

Dealer currently has boat and is rechecking above mentioned items but is stumped?

thanks for help"
 
"Does it run hot at idle or on

"Does it run hot at idle or only at higher RPMs? Has the short hose in front of the pivot housing been checked/replaced? Could have a hole in it reducing amout of water to engine. Could be worse at different trim angles.
Item #37 below.
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"Taking the input hose off the

"Taking the input hose off the t-stat and hold it facing upwards (grab a bucket), you should have about 2 to 4 inches of water coming out of the hose at idle."
 
"Scott - gauge is accurate, th

"Scott - gauge is accurate, they have used a gun to check
Chuck - will idle and plane both go hot.
Bob - Not sure on the hose - will ask and see what the if has been changed.

thanks for the help."
 
Have the manifold checked for

Have the manifold checked for blockage. I had the same problem and the manifold jackets were rusted shut. We had it glass blasted inside and that solved the problem.
 
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