Fluctuating oil pressure guage

[Calmseas]

Elbow failure on the port engine caused water to enter the oil. After replacing the elbows and multiple flushing and oil changes, the engine runs perfectly except now the oil pressure fluctuates between 27 psi and 50 psi at 2700 rpm. A quick throttle up from 1000 psi to 2000 psi, the oil pressure drops to zero and the low oil alarm sounds. New oil, filter and level is correct! No noisy lifters and engine runs smoothly. Should I direct my attention to the oil sending unit? Since it's a one way in, could it be clogged with that thick sticky mess? Can you tell me where on the port engine the sending unit is located? 2004 Mercruiser 6.2L MIE Horizon

 

[Lazy Daze]

You have a sender and a sensor - both are located by the "stock" oil filter mounting location... aft, port side. Follow your remote oil filter lines and you will find them. The sender controls your gauge, the sensor controls the alarm.

 

[Calmseas]

Help! Changed the oil pressure sending unit with an OEM one. Changed oil ( 25/40) and filter again. Oil level correct on the dip stick and the stick is correct in the tube. Engine has 600 hrs and ran perfectly before elbow failure. No lifter or bearing noise before or after.
My next options are, try a mechanical oil pressure guage to eliminate an oil pump problem.
Jump the port sensor to the starboard sensor to eliminate a faulty oil pressure guage. Am I going in the right direction?? Could the heat exchanger be clogged. Oil cooler or trans cooler??

 

[scoflaw]

Your going in the right direction. Forget the exchanger and the coolers

 

[Thornton69]

Confirm oil pressure with a mechanical gauge. No top end noise is promising. If you had ran the engine fore any period of time with water in oil, then it is possible the oil pump has been compromised. Almost sounds like it could be a cavitation issue with the pump.

 

[Capt.G]

With a mechanical gauge still fluctuate?
Sounds like pressure spring in oil pump or relief valve. Try taking the distributor out and get a drill with a oil pump rod and turn it in reverse direction and then forward to see if that loosens and thing that might be stuck. I would try that first before taking out the motor to change pump

 

[Shane Pikor]

Having trouble finding the oil pressure sender unit on my 5.0 MPI anyone have a good description of where i can find it

 

[Lazy Daze]

Having trouble finding the oil pressure sender unit on my 5.0 MPI anyone have a good description of where i can find it

See the second post in this thread.