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1st start of season - hot water coming out of only 1 pipe? No

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Mercruiser 350 Tournament ski, brand new impeller and housing.

Fired right up.

My temp gauge will not register, i think i need a new sending unit. separate issue.

However, the water coming out the pipes was drastically different. Starboard side hot, Port side stone cold.

checked all the hoses for any blockage, nothing.

Any ideas?

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Any ideas guys?

I ran it again last night and same issue. After running it I pulled the thermostat and it was closed. Like immediately pulled it after i shut off the motor.

Wouldn't you think it would be open?

Dumped the thermostat in a pot on the stove with a thermometer and it opened at 140 like it designed to.

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You said you checked the hoses, that would have been my first suggestion. There is a square water distribution block on the front of the motor. From that block there is a hose to the top of each of the exhaust risers. IIRC the block and hoses are before the thermostat and should ALWAYS have cold water in them when the boat is running to cool the exhaust. Check the outlets on the block and the inlets on the tops of the manifolds for rust/blockage. There are hoses and fittings on the bottoms of the manifolds as well. Check those ports for blockage too.

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Try it for a minute without the thermostat at all. In theory when cold, some water will bypass inner engine and go straight out to the exhaust to keep it from burning up as engine warms up and full circulation takes place.

Let us know that result,

Steve B.

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