Overheat question

VeroWing

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If the fan belt were to break, or idler pulley go bad while underway on my Magnum 350 alpha1 gen2, resulting in engine circulator (water pump on block) not working, would the lower unit pump still keep engine cool enough to go any significant distance, or would engine overheat immediately?
 

alldodge

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If the fan belt were to break, or idler pulley go bad while underway on my Magnum 350 alpha1 gen2, resulting in engine circulator (water pump on block) not working, would the lower unit pump still keep engine cool enough to go any significant distance, or would engine overheat immediately?

IMO you wouldn't be able to be on plane, need to stay around idle speed. Even at idle speed the engine temp may stay low enough at the thermostat housing (where the gauge sensor is), but inside the engine it could overheat and damage things. So if you can wait and be towed, get a tow
 

Bondo

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Ayuh,.... Wouldn't it be easier to just change the belt every 3 or 5 years, 'n carry a spare,..??

Normal "Preventive Maintenance" is usually more than enough to avert said scenario,...
 

thumpar

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If you are worried about it carry a spare. I have a whole tool set for the boat and even carry an extra impeller.
 

VeroWing

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I do have a new belt and carry a spare with a complete set of tools. In the belt circuit is the power steering pump, alternator, idler pulley, water pump, etc., of which any could go out at any time. I was just wondering if anyone had first hand knowledge if engine could still operate if one of these items put belt out of service. Outdrive pump would still be pumping water, and that's all that outboards have cooling themselves down. Reason I ask is that if I find that my I/O 350 would still overheat if one of these units failed, then I'm going to buy and bring spares of each on my offshore trips. I have towing service, but always like to be as self reliant as possible when on the water.
 

DeepBlue2010

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Replacing the water pump while on the water will not be pleasant. Make sure you dont have food in your stomach before you attempt this repair on the watet :)

To answer your question, try disconnecting the water pump belt and run your engine at idle and under load. You will find out and it would be great if you let us know. My guess is it will not be enough.
 

thumpar

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The problem may be that you don't if it is overheating. The sensor is in the thermostat housing that is fed by the impeller so you won't know the temp around the rest of the engine since the water is not circulating or maybe circulating very slow. My guess is that the cold water coming in closes the thermostat because there is no warm water flowing from the engine and the water just goes out the exhaust instead of the engine.
 

bruceb58

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You will overheat fast. Water near the back of the block/heads will be boiling hot.
 
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VeroWing

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Thanks for the answers. I think I will check this out for myself at dockside.
 

Bondo

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then I'm going to buy and bring spares of each on my offshore trips.

Ayuh,.... Why not bring along a fully dressed bobtail motor,.?... Ya might burn a piston someday,....
If yer packin' for any, 'n all possible failures, ya might as well just bring along a spare Boat in tow,...

I'm all for bein' prepared, I used to be a Boy Scout, 'n always have a toolbox near by,...

On my barge, I've got a reasonably equipped toolbox, 'bout 20" x 8" x 10",....
Other than a prop, 'n fuel filters, my entire "Spare Parts" kit, fits inside that toolbox, with all the tools, 'n a few rags,.....

If ya do a once over a couple times at the dock, 'n are diligent with yer Preventive Maintenance, ya don't need to bring along a full inventory of spare parts,...
 

VeroWing

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Hmmm, spare engine you say. Guess you're right, maybe I'm being overly cautious.
 

bruceb58

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I have belts in my boat along with the tool to change them. They are belts I took off when I changed them for preventive maintenance. In all the years I have been boating...close to 40 years...have never broken a belt.

In fact, I have never broken a belt in a car either but I change them every 50K miles.
 
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