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Oil pressure issue

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al ralston

New member
Since launching this season, I ran the boa a while, then WOT. Ran great, but when came down from WOT, oils pressure plummeted and alarm went off. i chanced the oil and filter - same thing. Im told that, because the pressure sender and alarm sensor are separate, likely a problem with oil pump. need to pull engine and replace...more big bucks and down time. Any second opinions to consider? this is a 2002 5.7 mercruiser w/340 hours.
Thanks
al
 
Electric oil pressure sending units and electric oil pressure guages can fail.

Connect a mechanical guage into an oil galley port, and verify that you have or do not have adequate oil pressure.

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could have 2 different problems .most alarms have temp, oil pressure and drive oil together. per rick, oil pressure gauge
 
Thanks very much to you both! My understanding from what I've read is that the pressure sender and the alarm sensor are two independent units not likely to fault at the same time. This is also what how the mechanic is justifying next step of pulling the engine. Is there a link between the two? If so, how would one trigger the other?
Al
 
your mechanic should install a mechanical gauge to verify no oil pressure.
the no engine oil pressure, no outdrive oil, engine overheat alarms are all wired together.
 
Thanks Bt Doctur
I agree, though the mechanic says "no chance" or sensor/sender malfunctioning at same time. I am trying to understand other possible root causes before throwing in the towel and having the engine pulled. I don't understand how the oil pump can be the root cause given the symptoms (again, pressure fine until after I run WOT and bring it back down to low RPM - both times exactly the same. Then low pressure at low RPM after. No other symptoms - engine starts/runs fine, temp stable, etc.).
I have had others tell me possible blockage in the "T" fitting that feeds both sensor and sender, possible blockage in oil filter mount, or in other oil ports. Again, how a blockage would result in consistent symptoms described doesn't make sense (but I am not a mechanic).
I will ask the mechanic to check pressure with gauge - only sure way to know.
Any other "quick checks" I can do myself (like change sensor and sender, check for blockage in T fitting, etc.) let me know your thoughts. Appreciate your feedback greatly.
Al
 
a oil pressure gauge is the only way to verify engine oil pressure. sometimes if the crankcase is overfilled, the oil will foam up and pressure goes away.
another cause is a "Hi-volume" pump with a 4 quart pan. the pump sucks the pan dry.
To thin of an oil, should have 25w40 in it
 
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