Oil pressure

[RichRab]

2002 merc I/o 5.0 mpi about 700 hrs. I just noticed that after boat is warmed up from going through no wake zone that at 2000 rpm the oil pressure goes from around 40 psi and then around rpm 20 at 3000 rpm. Changed oil and filter at end of every season using merc oil and filter. Oil level is good. Bad filter maybe?

 

[Bondo]

Ayuh,..... Rule of thumb is 10 psi per 1000 rpms,.....

Did ya check the oil Level,..??

 

[RichRab]

As stated...yes. Thank you. RR

 

[keith2k455]

I was always told the 10psi per 1000 rpm rule for a minimum.

What weight oil are you using? Unfortunately I would guess you have a blockage somewhere or a bad cam bearing.

 

[RichRab]

I will check. Thanks.

 

[Bt Doctur]

Before you draw and conclusions, install a mechanical gauge

 

[NHGuy]

The mechanical gauge is super easy to thread in, at the rear port side. Inexpensive great diagnostic tool to have in your box.
When you do pull the filter save the contents and inspect. Pour the contents into a glass jar or zip lock bag and give them time to settle. If you could cut the filter in half the horizontal way that would help figure out your issue too.

 

[RichRab]

Where exactly am I installing the gauge. In the spot that an existing sending unit goes? Thank you. RR

 

[keith2k455]

The existing unit spot wold be fine

 

[Alumarine]

On my Glastron there was a tee there with a plug in it, probably for an alarm that wasn't installed.
I just removed the plug in the tee to hook up a temporary manual gauge.

 

[RichRab]

Marc--what were you checking for and what was your outcome? I will check when I get to boat. Thank you. RR

 

[RichRab]

After alot of thought I bought a filter and sending unit since the easiest thing would be to change the filter first and that corrected things. Thank you. RR

 

[Silvertip]

I can't imagine you got a bad filter but Murphy's Law seems to apply more to boats than cars. Are you certain the filter was the correct one for your engine and that it was correctly installed? Mismarked perhaps? That can affect oil pressure.

 

[RichRab]

It was fine up to a month ago. I usually double check the numbers but will triple check it. Only one way to screw on a filter. Thanks RR

 

[Alumarine]

Marc--what were you checking for and what was your outcome? I will check when I get to boat. Thank you. RR

Sorry, I missed this.

I was just checking to how the built in gauge compared to my manual gauge.
They were the same. 40lb at 3000-3500 when engine was warm.

 

[RichRab]

Update...I did not change the sending and last week pressure went to zero when cruising. Motor sounded fine and there is a fuel pump cutoff. I replaced the sending unit that broke off while unscrewing it. Unscrewed nipple in block and took it to local marina whole took oil sensor off then heated nipple and drove in a tool for unscrewing square plugs and surprisingly to me the broken piece came out. Reassembled and all looks fine. Thanks. RR