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2005 Monsoon 340 with high oil pressure

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I changed my oil this weekend with a NAPA 1069 oil filter which I believe I saw recommended somewhere on this site. I noticed the NAPA filter was deeper than the filter I removed but didn't think that would be an issue. Unfortunately I can't remember brand or # of the one I removed but probably Indmar from Bakes.

When running the engine after oil/filter change I noticed the oil pressure was much higher than usual. @2000 RPM I am usually about 40 PSI and now I'm at 70+ PSI. I always check when starting the boat to make sure I don't have low pressure but never thought I would be worried about high pressure.

Can the wrong oil filter change the oil pressure? Can high oil pressure damage the engine? I'm sure under load and higher RPM's I'll easily be pegging the gauge at 80 PSI.



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If you're using 15w-40 oil like me, 70 PSI when cold seems to be about what I get. If you're sure this is higher than you normally see on a cold engine and you didn't refill with a higher viscosity oil then I would check the sending unit connection to be sure you didn't knock it loose when changing the filter. I'm not sure where the pressure reading is taken - whether it's on the inlet or outlet of the filter - but if it's on the inlet and you had a filter with a restriction that caused pressure drop across the filter you could see a higher pressure on the inlet and lower on the outlet. Pressure drop will only increase with flow (RPM in this case) and could create low oil pressure to your engine. That's about the only reason I could think of for a new oil filter to increase oil pressure but that would only be if the reading was taken at the inlet to the filter so I may be totally wrong in my thinking here.

Did you fill up the filter with oil before installing?

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I will definitely check the sending unit connection when I get home. I did use 15-40 and always have although different brand. 

I did not fill the filter but never have before. Could that cause this?

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That is one of the correct filters from napa. The other larger option, which I use, is 1060. No, not filling the filter would not cause high pressure. You could get high pressure from a filter if you didn't change it and it was really dirty. I too vote the sending unit or the gauge itself.   

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I ran the engine at about 1500 RPM for 10-15 minutes and it never went down.

I ran it for about 10 minutes before changing the oil and pressure was normal. 

When I changed the oil I also changed plugs, wires, cap, rotor, and impeller but can't imagine anything there would affect oil pressure.

Can high oil pressure cause any damage to the motor?

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My 99 has run 40-80 under load.  sometimes lower at idle.  If your concerned, swap in a new oil filter (and top off the oil) on the slim chance that the oil filter you have has a faulty bypass valve. 

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High pressure will not cause any damage.

If you rule out any connection problem with the sender next thing I would do is turn ignition on and remove the sender wire - oil pressure gauge should drop to 0. Then ground the wire and it should read full scale. That would rule out the gauge. If you have a multimeter crank the engine and see what resistance you get at the sender terminal: 33-240 ohms is the correct range. 

I asked about filling the filter with oil first because of a conversation I had a while back with a compressor technician who said they always fill oil filters on rotary compressors because the sudden shock of oil filling the filter upon startup and slamming into the pressure transducer could sometimes damage them. Different application with much higher pressures I know, but just a thought that occurred when I read your situation. I've not always remembered to fill my filter and haven't had an issue.

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