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New 1998 Four Winns 220 Horizon owner - pontoon is gone, kids and dad want to go faster!

My brother has a Bayliner and when he turns on his key the oil pressure alarm screeches untill he starts the engine. However, my 5.7L Volvo Penta Beeps for 1 second and stops. I just want to make sure this is correct operation for the Volvo engine/Four Winns. Should it continue to beep until started?

Also the oil pressure gauge needle runs in the middle during normal operation. However, at engine idle (hot engine) the needle drops way low, just above the red. The oil was just changed at a Four Winns dealer (but by previous owner - I do not know the viscosity). I have been doing some google searches and this sounds common.... Does this sound common / ok? Just do not want to hurt my new baby!

Thanks,
Jeff

Pressure dropping at idle is quite normal; my 1999 5.7 engine ( with ca 220 engine hours before I sold it ) used to do that, just above the red at idle but mid range the rest of the time. If the low pressure alarm goes off that would need investigating though.

Graham

Hi Jeff,
My 2001 Horizon with 5.0 Volvo Penta beeps continuously until the engine starts and pressure builds.
Very annoying if you are trying to test out wiring that requires the ignition on with the engine not running.
Sounds as if your oil pressure is working OK and I would not worry too much as long as the oil warning buzzer doesn't come on.
Oil pressure will drop as the oil rises in temperature. The equation is PV=RT (pressure x volume = a constant x temperature) Assuming volume is constant the pressure is inversley proportional to temperature. So as temp rises pressure drops.
The amount of drop will vary depending on the health of the engine, viscosity of oil, and type of oil (synthetic vs dinosaur). If you are concerned it is too low you may want to install an accurate pressure sensor and gauge to see what actual PSI you are getting. A hot engine, in good shape, running a 15w-50 mobil 1 type synthetic oil, should be at least 15 PSI at idle.
Just my .02
Rob

_________________
Anything Worth Doing Is Worth Overdoing
2001 Horizon 180

Rob, if I remember correctly, that's one of the the standard gas equations, I didn't think it could be applied to liquids! I thought the pressure drops as the pump is pumping less oil at idle than at higher rpm (and pressure when hot is less as the viscosity is lower); at higher RPM the pump produces more and more pressure, which is controlled by a pressure relief valve.

Graham

Hi Graham,
You are correct about both. I had a brain fade and should have used the equation (fluid mechanics instead of the ideal gas law) below to explain.

As engine rpm increases the pump will move more oil. That is why the pressure reads higher at higher rpms.

At the same rpm (say initial startup at idle versus idle after a half hour run)
Oil pressure change due to heating is due to a change in density or viscosity of the oil. So as the temperature increases the density decreases the pressure will decrease as well.

When temperature is changed the density of a fluid can be expressed as

ρ1 = ρ0 / (1 + β (t1 - t0)) (1)

where

ρ1 = final density (kg/m3)

ρ0 = initial density (kg/m3)

β = volumetric temperature expansion coefficient (m3/m3 oC)

t1 = final temperature (oC)

t0 = initial temperature (oC)

Rob

_________________
Anything Worth Doing Is Worth Overdoing
2001 Horizon 180