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Nissan NSF4A2 Cooling Water Flow

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NoMechanic

New member
I purchased a used NSF4A2 4hp 4-stroke. I tried to run it yesterday, and did not get any water flow out the port located above water at the back/bottom of the motor. When I checked it, it looked like the small hole was plugged with a white powdery corrosion. I used a wire to try to clear it, but only got about 1/8 inch in. I also tried to unscrew it, but it did not turn. Any advice is appreciated.
 
NoMechanic said:
I purchased a used NSF4A2 4hp 4-stroke. I tried to run it yesterday, and did not get any water flow out the port located above water at the back/bottom of the motor. When I checked it, it looked like the small hole was plugged with a white powdery corrosion. I used a wire to try to clear it, but only got about 1/8 inch in. I also tried to unscrew it, but it did not turn. Any advice is appreciated.
Click to expand...

After reading some other forum posts, can just use a small diameter drill to initially clear this outlet?
 
Yes, but... Have the motor running (in water, of course), and push a stiff wire or monofilament into the pee hole to clear the debris, which can then get flushed out with the water stream. If you enlarge the hole with a drill, you will lower the back pressure of the water gallery, and may cause a decrease of cooling flow through the upper powerhead.
 
pvanv said:
Yes, but... Have the motor running (in water, of course), and push a stiff wire or monofilament into the pee hole to clear the debris, which can then get flushed out with the water stream. If you enlarge the hole with a drill, you will lower the back pressure of the water gallery, and may cause a decrease of cooling flow through the upper powerhead.
Click to expand...

I understand the concern about enlarging the hole. Is it safe to assume that the hole is straight up through the port and a consistent diameter?
 
pvanv said:
Nope. It's a chamber, and you only get about 1/4" or 3/8" into it from the hole.
Click to expand...

Ok, no drilling. Can I easily remove the entire port to clean? The wire I used was not flexible and went straight in about 1/4". Sounds like I need some stiff, but flexible wire? Thanks for your help and patience.
 
The chamber is cast into the motor base. As long as you are pumping OK, poke the hole while running, wiggle it around a bit, and you will dislodge the crud. You will not push several inches of fish line in; the clogging always seems to be at the chamber outlet.
 
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