Oil pressure drop

[soh_2]

Good Morning,<br />I noticed before I took our boat out for the winter, that when we were running @ 4000+- rpm that oil pressure would drop to about 20psi then jump up to 60-80 psi without any throttle changes.<br />I change the oil & filter every 50+ hours.<br />When it was changed a couple of days ago and engine ran, there was a strange noise.<br />The engine is a 454 OMC w/270 hrs.<br />Any help or suggestions before next spring would be appreciated.<br />Thanks

 

[Haut Medoc]

Re: Oil pressure drop

Welcome to the forum at iboats .....What kind of strange noise? A bad bearing can cause oil pressure drop.....What does the pressure do at idle? Stick around for more input...There are some pretty smart people here....JK

 

[searay3]

Re: Oil pressure drop

Do you have access to a manual guage? Electric guages can jump around because of connections, or a shaky guage. Be sure the ground is good. Usually a couple of guages will share a connection behind the dash. Remove-clean-replace the connections. Just tight probably isn't good enough. If there were issues in the motor, there would be rumbling (main bearings) or hammering (rod bearings).

 

[Don S]

Re: Oil pressure drop

You don't really give much information about the noise, plus noises are pretty hard to explain in typed words. An automotive stethescope would sure help to lo locate the noise as to front, middle, back of engine, drive area or gimbal bearing/ujoint noises. Your oil pressure may not be the cause of the noise.<br />As mentioned, using a mechanical gauge will eliminate the electrical problems between the sender, wiring, and gauge. Usually an engine problem that causes low oil pressure will not suddenly go back to normal. <br />Only 270 hours on an OMC means there is not a lot of hours, and not being used causes more problems than overuse. <br />Any records of drive removal, ujoints, gimbal bearing, bellows problems? That is a very common area for noises in I/O's.

 

[soh_2]

Re: Oil pressure drop

Thank you for ALL of your responces.<br />I will try to obtain a manual guage first and check that out, along with cleaning terminals and reconnecting guages. <br />As Don S. mentioned,it is hard to describe the noise and location other than I have never heard it before.<br />Any idea where to get an automotive stethescope??<br />I have owned this boat for 2 yrs and put on 100+ hrs w/o any problems.(I mean this problem)<br />I planned on having the outdrive serviced over the winter, no problems I know of as of know, just wanted to have checked & seviced.<br />Are there any other ideas or causes that I could look at before I pull the boat for the winter?<br />Again thanks for all you help & ideas

 

[Destin]

Re: Oil pressure drop

If the oil level is too high the crankshaft can aerate the oil and cause the oil to foam up and the pressure to drop at high RPM. Sometimes the air will cause the lifters to collapse and the valves start clacking. Try lowering the oil level to the low mark on the dipstick and see if the pressure is OK.

 

[soh_2]

Re: Oil pressure drop

Destin,<br />I'll try that this weekend, before it comes out.<br />If I lower the oil level in the crankcase,do you think the noise will stop, or has the damage has been done?

 

[Destin]

Re: Oil pressure drop

IF your original problem was foaming at high RPM caused by too much oil, then everyting is probably OK. When you restart, the pressure should be normal and the valves should quickly quieten.