no oil pressure at idle after warm up

[ashleyt1001]

I just bought the boat 2 weeks ago took it out with the owner and oil pressure was fine. I took it out today and the oil pressure was at zero after warm up at idle but went to between 40 and 60 psi while crusin depending on the rpm. Please help is this a gauge problem or oil pump problem or something else

 

[Philster]

Re: no oil pressure at idle after warm up

Who put the oil in it? Did you? If not, get it out and add the proper amount and the correct weight oil for marine engine use.

Don't run it until you do that, and change the filter. Then check the pressure and if there is an issue, you eliminated the first thing you should have anyway.

Why do this step first? You bought a used engine as part of this deal. All the fluids, including the drive fluids, should be drained and replaced with the recommended fluids. Then you are at the next step, which is thorough RE-inspection of everything before you fire it up.

Also, how old is the engine? The fuel? How many hours? Could it be a tired/worn engine that he dropped some super heavy oil into for a test drive to cover some issues? We need more info.

Regardless... I stand by my recommendation. Run it on your own essential fluids, not the ones the previous guy left in 'er.

 

[Bondo]

Re: no oil pressure at idle after warm up

Ayuh,... Plumb in a mechanical gauge to find out what's goin' on...

Check the wiring for the gauge there now...

What's this boat got for a Motor,..?? by Whom,..?? what Drive,..??

 

[ashleyt1001]

Re: no oil pressure at idle after warm up

the oil was just changed mercruiser synthetic

 

[ashleyt1001]

Re: no oil pressure at idle after warm up

1988 mercruiser 3.7

 

[Philster]

Re: no oil pressure at idle after warm up

Did you use the proper weight oil?

Is there enough in there?

Proper filter?

You changed the oil and the pressure dropped. The gauge went bad or the oil is the issue. Which do you think is more likely?

It is also possible that the baseline pressure at idle always reads low and that you are there with the right oil now. It's possible that you have everything right, and the previous owner had some old gunk in there or some additive to cover up something.

 

[Don S]

Re: no oil pressure at idle after warm up

As bondo mentioned, put a mechanical gauge on it and see if you actually have oil pressure at idle. It's possible the sending unit could be bad at the lower oil pressure setting. The mechanical gauge will tell you for sure.

 

[Bondo]

Re: no oil pressure at idle after warm up

I just bought the boat 2 weeks ago

Ayuh,... Welcome Aboard,...
Are ya Handy,..??
The factory shop manuals are available for download up in the Adults Only section at the top of this forum,...
Grab a copy of the 1s for your motor,+ drive,....

You'll also want to do a search for Mercruiser 470, or just 470....

Good Luck,...

 

[boat1010]

Re: no oil pressure at idle after warm up

Like Bondo and Don said, get a gage that you know works and see where you are at. My sending unit went out and pretty much did the same thing. Pretty cheap fix. Made my heart stop beating so fast after changing the sending unit.