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Nissan NS8B cooling output - question

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So my 8HP runs perfectly fine, but no water spits out of the discharge hole up top. I let it run for 30+ minutes, and it is plenty cool. Lots of water coming out of the other discharge just where the bottom of the powerhead mates to the shaft housing.

Water pump impeller is new (about 30 hours on it). I noticed over time that the water stream coming out of the discharge was getting weaker and weaker, until one day it just stopped.

So is it fine? I checked for blockage but I cant see anything. Is there a common place for the discharge to be blocked? Unfortunately I don't have access to a shop anymore so I'd like to be able to fix it off the back of the boat...

Thanks for any input!
 
The motor can cool just fine without any flow through the telltale. But, without a running telltale, it's difficult to be sure that everything is OK. Typically, salt and crud, or occasionally a mud wasp can clog the telltale port. Standard procedure to clear the port is to run a stiff wire or weed-whacker line into the telltale as far as it will go while the motor is running. That procedure will usually dislodge any blockage so it can be flushed out with the cooling water.

30 hours on an impeller may not necessarily classify it as "new". Standard interval is to inspect the wp every year/season. In cold fresh water in the great lakes, we sometimes get 3 years, but in most other areas, it is a lot less. If you do decide an impeller is warranted, I would recommend doing the whole wp kit, as the parts cost is small compared with the labor, and the kit includes the plate and cup, which are often-overlooked wear bits.
 
Thank you for the reply. I will try what you said to attempt to unblock the telltale.

You are right, 30 hours on a impeller is no where near close to new. I installed it last summer. I wish I would have known about the whole WP kit, I was not aware one existed. Thanks again!
 
I should have updated this sooner, but I did exactly as you said and the telltale starting working perfectly. Thanks!
 
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