Oil Pressure

[Russ Calasant]

I am hoping someone can shed some light on a new issue I am experiencing. My port motor, 97 7.4 MPI, show good oil pressure upon starting, idle and run up at all RPM's however after running for a priod of time when brought back under 1000 RPM the pressure drops down to less than half but sounds no alarm. Oil level is good. If you run it back up the gauge increases back to normal level. Starboad side runs consistantly at same acceptable level no matter the RPM. :huh:

 

[Kay Lee]

Exactly what is less than half? Depending upon the actual oil pressure you're seeing, it seems normal to me. The starboard engine appears to be the one acting abnormal. You might have a bad sending unit or gauge on the starboard side. You could also have a bad low oil pressure switch on the port side.

Larry

 

[katricol]

Never done this before Russ ? Something new. Is it possible this is back-pressure from a filter that has seen a summer's use?...and therefore not a real problem.

 

[Russ Calasant]

Exactly what is less than half? Depending upon the actual oil pressure you're seeing, it seems normal to me. The starboard engine appears to be the one acting abnormal. You might have a bad sending unit or gauge on the starboard side. You could also have a bad low oil pressure switch on the port side.

Larry

Larry, I will have to look at the gauge. As far as the starboard your observation makes sense, the thought crossed my mind - based on my understanding of how the pump works. How does your gauge work? operating pressure/RPM?

Never done this before Russ ? Something new. Is it possible this is back-pressure from a filter that has seen a summer's use?...and therefore not a real problem.

No, it never did although it always read a little lower than the other. I am not sure but tryin to get a better understanding.

 

[Kay Lee]

Russ,

When my engine is cold or running at 3000+ RPM's, the pressure is around 70 psi. At idle, after reaching operating temperature, it's around 30 psi.

Larry

 

[bankshotbankshot]

I had a problem like this before not trying to freak you out, but I had an engine one time that had erratic oil pressure at times then be totally fine. Im a Mercruiser Tech so I called Mercury and they said change out the sensor (because those things always go bad even on brand new boats 2011's) of course that did not solve the problem. Checked the oil pressure with a manual gage and same thing some times great oil pressure some times crappy oil pressure same as gage on boat. So I called Mercury probably 5 times and they said pull the engine out and inspect the oil pan and the oil pump pickup (this is warranty work so Mercury is paying every dime of this). Any ways 6 hours later I pull the engine and take off the oil pan and BAM the oil pickup from the oil pump fell into the oil pan it was some times in the oil pump and some times it would dislodge and give you low oil pressure. Hope this is not what happened to you just sharing my story