www.iFourWinns.com

1998 5.7 GSI . When I start my boat my oil pressure runs a steady 40lbs. and will continue to do so as long as idle [always at least 10 min. at 1000 RPMS] . When I pick up speed and plane off [3500 to 3800 RPMS] the pressure remains steady . When backing down for a no wake area [1000 RPMS] the oil pressure will drop to 18-20 lbs. and fluctuate a little for several minutes before gradually increasing to 40lbs. again . I know its not the gauge because I've used two. Is this normal ? If not , any suggestions ? thanks to all that respond .

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1998 VISTA 258

I would keep a close eye on it. I always say, keep it simple. Try a oil change, maybe something is in the filter?

Sounds like oil surge in the pan - nothing to worry about. Wondering what type of oil you are running... warm idle should be in the range of 15-20psi, at 3000rpm I would be expecting around 50psi. I suspect that either your oil sender or gauge is not 100% accurate. Try swapping the sender first as this is the cheapest and most common cause.

Small block chevs hav an absolutely terrific lubrication system and are seriously overdesigned in this area so I would not worry too much. I raced these engines for over 20 years and lubrication problems were rare and usually caused by something else.

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Alec

2006 Horizon 190
VP 4.3GL/SX, Sunsport

thanks guys . I'm running straight 30 wt oil and I have changed the oil and filter , didn't help . I put in a new gauge cluster this spring so its not the gauge [old one read the same ] .I'll try replacing the sender . Glad to hear it might not be a big deal .

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1998 VISTA 258

OK with 30W oil, the pressures you are seeing on the gauge are about what I would expect. Seems that after idling for a while the pressure just creeps up, so nothing serious - my money is still on the sender!

Looking at possible alternative causes, I can't think of how the oil pump itself or bypass valve on the pump could possibly cause this, even if some of the oil galleries were blocked.

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Alec

2006 Horizon 190
VP 4.3GL/SX, Sunsport

On a quick decceration you will drop oil press quickly and below normal idle condition. That part is normal.
But for it to take several minutes to come back and not less than 10 seconds or so means your sender is faulty.
Quick cheap change. Well I don't know about quick as to were yours is located............

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1992 Baja 38 Special Twin 502 Mags

03 Stingray 3.0
88 261 Liberator 460 King Cobras
95 Bayliner 1850 3.0
77 Fiber Form 20ft 350/385hp
70 Wescraft 1800 SS 455 Jet

Lead, Follow, or get the Hell out of the Way!

Have you changed from synthetic recently? I was told by my dealer that mixing them can cause the gauge some unhappiness.

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Paul
2007 Four Winns Horizon 220
Mercruiser 350 Mag MPI w/ Bravo III Drive
2004 Ford Explorer Limited (V8-AWD)
Pomme de Terre Lake (Southwest Missouri)