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No oil pressure

R

rocking4d

New member
I have a NSF4B Nisan 4hp 4 stroke 2005. The warning light is flashing or is on continually. I replaced the oil pressure switch and that didn't correct the problem. I took the oil pressure switch out and installed a pressure gage. Started motor and gage needle flickers between 0 and 3 lbs. I just bought the motor so I don't know it's history. I can tell it hasn't been used that much. I do know it hasn't been run since 2007. Any and all suggestions welcome.
 
If the oil level is correct, and you are running the proper oil, you could have a clogged oil pickup strainer, or a jammed oil pressure regulator "plunger" (or possibly a broken spring in the plunger assembly). The plunger is accessible without removing the pan... or... if that all checks out... you either have a bad oil pump and/or too much bearing clearance. In order to pull the pan, you must remove the power head. Once the pan is off, you can inspect the strainer, as well as the oil pump clearances.
002-21046-4_FIG04.jpg
 
I noticed when I start the engine the oil pressure gage goes to 25 lbs for about 1 second then drops to 0 an stays at 0.
I'm using CARQUEST SAE 10W-30. Is that ok.?
 
Your oil level may be low (or way too high and aerating). If so, once the gallery fills, the pump draws air, which compresses, resulting in a drop in pressure. Check that the oil level is between the 2 hash marks on the plastic dipstick/fill plug when the plug is screwed in.

There is a possibility that the plunger is sticking partially open; that can be inspected without pulling the power head. Also, if the strainer is restricted, the pickup might fill slowly while the motor is off (allowing a good initial pressure), but then preventing enough flow when running.

That oil is the correct viscosity, but we would prefer that you run non-synthetic, NMMA-certified type FC-W oil, as it has better anti-corrosion characteristics, and great anti-foaming.
 
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