Low Oil Pressure

[backyarddummy]

I have 2000 Four Winns bow rider. It has a 5.0 Volvo Penta SX. I am getting low oil pressure when I left off the throttle. It doesn’t happen all the time, but if I at crusing speed for a bit then slow to an idle the oil pressure drops and the alarm goes off. If I give it a little gas it usually jumps up again and the alarm goes off. Hoping it’s something easy to fix, anyone have any ideas?

 

[dwco5051]

Is this a new problem or has it done since you have had the boat? I am thinking the possibility could be the oil level in the oil pan changing due to both de-acceleration and the motor angle changing as you come off plane. I will admit I know nothing about the baffle system in you oil pan but can remember from my involvement in dirt track cars from over 50 years ago that we built baffle boxes in the sumps. Important on short tracks when centrifugal force would push the oil to and up the sides of the sump due to constant turning left. Just throwing this out there for discussion.

 

[backyarddummy]

Is this a new problem or has it done since you have had the boat? I am thinking the possibility could be the oil level in the oil pan changing due to both de-acceleration and the motor angle changing as you come off plane. I will admit I know nothing about the baffle system in you oil pan but can remember from my involvement in dirt track cars from over 50 years ago that we built baffle boxes in the sumps. Important on short tracks when centrifugal force would push the oil to and up the sides of the sump due to constant turning left. Just throwing this out there for discussion.

It’s been happening for the past two or three seasons, previous to that I never had a problem and I’ve had the boat for about 12 years.

 

[Scott Danforth]

first, get a mechanical gauge and screw it into the oil passages to get a real reading. you could simply have a bad sender.

however since the gauge and the alarm are two different senders, you may have low oil pressure. what are you reading for oil pressure?

what viscosity of oil?

if you have a higher viscosity of oil and your oil pressure is dropping below the 10psi alarm point. then you may have a problem and I would recommend pulling the engine, pulling the pan and looking at the oil pump and pickup.

 

[backyarddummy]

Hey Scott sorry for the delayed reply. I use 10w30 for oil or so they tell me at the shop that winterizes the boat. Guess I’ll have to get a gauge and measure myself. Like I said it’s only after throttling down after high idle so tough to replicate in the driveway. Excuse my lack of knowledge but where would the best oil passage to measure at or is there multiple spots I should check?

Tim

 

[Scott Danforth]

Hey Scott sorry for the delayed reply. I use 10w30 for oil or so they tell me at the shop that winterizes the boat. Guess I’ll have to get a gauge and measure myself. Like I said it’s only after throttling down after high idle so tough to replicate in the driveway. Excuse my lack of knowledge but where would the best oil passage to measure at or is there multiple spots I should check?

Tim

You should be using 20w-50, or at least 15w-40

There are 3 spots on the block to take oil pressure. My suggestion is use the one on the back of the block

 

[saaristo]

I would say the oil viscosity is the culprit here. Thats a typical behaviour when coming down from plane the pressure drops. Like said before me - start from changing the oil to a higher vis one....

 

[BRICH1260]

I know its obvious but double check the oil level. If you are a quart or two low, your oil pick up may have trouble supplying a steady flow as the boat tilts and rolls. If you do change the oil, and I suggest you do that, measure how much oil comes out and see if it was low.

 

[Lou C]

I agree that a conventional 10w/30 is not really adequate for marine inboard use. The marine engine companies themselves have said this, unless:
you use full synthetic oil (Volvo recommended 10w/40 full syn)
or the engine has an engine oil cooler
Otherwise:
20/50, 15W40, 25/40, or straight 30 or 40.
I use 25/40 Merc/Quicksilver oil and the lowest I ever see after coming off plane is about 25 psi. Normally it is 40-60.

 

[backyarddummy]

I appreciate all the responses, I will be changing the oil this weekend and hopefully getting on the water soon to test it out with my new pressure gauge! You guys have been great, thanks to all. I’ll keep you posted.

 

[QBhoy]

Although I’d think you should use a 15w40 in there…I don’t think what you are using is solely to blame for your issue. It’s more likely that your oil has become thin and diluted with fuel, if she is a carb and has been ran at idle for too long for a sustained period…or your engine is running cold perhaps ?
Low oil level as mentioned could also be to blame too.