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Tan
Tan, MerCruiser Certified Technician
Category: Boat
Satisfied Customers: 10620
Experience:  40 yrs. experience with complete engine repairs both inboard/outboard and MerCruiser Certified Technician.
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How to trouble shoot overheating problem on a Boston whaler

Customer Question

How to trouble shoot overheating problem on a Boston whaler jet boat?with a turbo jet,johnson evinrude 115JEEO motor.
Submitted: 6 months ago.
Category: Boat
Expert:  Tan replied 6 months ago.

Hello. My name is Tan.

Ok the jet pump is your water pump so the only things that will cause over heat are, bad thermostats low speed engine operation, pressure relief valves high speed engine operation. Then finally blown head gaskets or blocked water passages.

The thermostats are located at the rear of the engine base of the power head. Here is a pic of the t-stats # ***** and pressure relief valves # ***** 2 of each. To check for water flow to the cylinder heads remove the bottom hose on the head. http://www.boats.net/parts/search/OMC/TurboJet/1995/115JEEOB/ADAPTOR%20&%20MUFFLER/parts.html

We need to start with a compression test first.

The compression must be 90+ psi with no more than 15 % difference cylinders. http://www.boats.net/parts/search/OMC/TurboJet/1995/115JEEOB/CYLINDER%20&%20CRANKCASE/parts.html

If compression is good replace t-stats and pressure relief valves.

The only way to check them is to remove them a physically put them in hot water. If I take the trouble to pull them out I just replace them. Then that problem is eliminated. Same goes for the pressure relief valves # ***** and seats # *****

Post back with questions and findings.

Thank you...Tan

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