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overheating in a lake!

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Just wondering if any of you have ever had the pleasure of having your boat towed across a lake because the fucker overheated while floating in a massive body of 55 degree water? It happen to me this weekend and it felt pretty ironic.

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Nope,but this weekend also rite near where we were camped I watched a guy jump out of his mercedes(dealer plates on it) to yell at some one while his benz rolled away down a hill and jumping a couple boulders before smacking into a tree just before the lake. Crazy shit!

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A boat has a raw water pump.  They are usually a rubber vane impeller, with the vanes squished on one side of the water pump housing.  it you run the boat without supplying water to the impeller for even a few seconds, the vanes make direct contact with the metal water pump housing and over heat, burn or wear a lot.  It severely weakens the vanes.  They will soon fail.  If not on that trip, soon after.


On inboard boats, this water pump is usually on the engine.  On outboard boats, or inboard/outboard boats, this pump is usually in the lower unit.  


It is a good idea to check this impeller at the beginning of the boating season.

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"Could it be clogged with weeds or mud.... or is this even possible. I don't own a boat"


That is very possible.  Also, if you remove the old impeller, and it is missing some vanes, you have to find them, because they will lodge in a spot, and very possibly restrict water flow.


An inboard engine in a boat basically uses a raw water pump with way more capacity than the engine needs.  I have a 351 engine in my boat, the raw water pump will pump about 20 gallons of water in a minute, at 3000 engine RPM.  Most of the water just goes straight to the exhaust manifolds to keep them cool.  The circulating water pump moves water in the engine.  When the engine block water gets warm, the thermostat opens, and it dumps some hot water out the exhaust, and the hot water is replaced by cooler lake water, and engine temp is maintained.

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Its already fixed,the impeller went lost its veins like DanielC said. I was hoping for a clog at the moment ,but it was cheap easy fix and took it for a quick run this morning and it ran about 20 degree cooler than I was use to seeing. I will be paying more attention to the temp. My boat also has a 351 and with the new impeller it ran through 5 gallon in about 15-20 seconds at 3000 rpm.

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On many 351 engines, the raw water pump can be installed upside down.  This is to accommodate some marine engines that rotate backwards,   A normal rotation engine turn clockwise, viewed from the front.  Like a Datsun L engine.  A reverse  rotation engine turn counterclockwise.

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