Oil Pressure Variation - Black Scorpion
 

My Sanger V210 has 520 hours on its Black Scorpion Mercruiser. This weekend I noticed a problem with the oil pressure. At riding speed (20-23 mph / 2800-2950 RPM), the oil pressure is low, and bounces around a lot. It varies from normal...down to the low/warning level in a random manner.

The oil level is fine. When I first noticed, I checked the oil...it was at the low end of the OK range. It took less than 1/2 Qt to top it off...so that was not it. The oil looks clean (about 75 hours on this oil...so I will change soon.) The engine is running at normal temperature, and other wise seems fine.

When I speed the boat up to 25-30 mph (3100-3250 RPM), the oil pressure is rock solid normal.

If it were the gauge, it would be jacked up all the time. Any ideas what this could be...?

Thanks in advance,
-Brant

I would suspect an eratic guage, sender, wiring or guage control module before suspecting the engine myself. There should be a way to hook up a manual guage and at least scratch the engine off the list of possibilities.

Sparky,

I was planning on doing that...but I don't really think it is the gauge. At 20-23 the oil pressure is all over the place...and at 25 mph + it is rock solid. If it were a gauge, wouldn't it always be erratic?

I have heard that the oil pump shaft can go bad, and the issues will first be apparent at lower RPMs....

That would suck...as I will have to pull the motor to change it.....

I had the same issue with my Mustang Cobra. I change the oil pressure sender on the block, 12 bucks at auto zone, and it fixed the problem. The gauge either works or not. My money is on the sender in the block.

If it was a mechanical guage I would say yes it would be eratic all the time but since the signal is converted through the dash module before it reaches the guage, it's harder to diagnose.

My gauge that was all over the place was the electric kind. A sender in the block and a guage in the dash. Change the 12 dollar sender in the block. That is the cheapest and easiest compontant.

I am with Dave. I had a similar prob. with mine, at low rpm the dash alarm would sound and the display would say ' low oil p ". I replaced the sending unit and the problem went away.

Thanks guys...you were close. It was a loose wire. The boot that attached the lead to the sender unit was super loose. Crimped it a bit...now the gunge reads fine. Problem solved.

Sweet. It's nice when its simple.