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low oil pressure
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Author:  powermaker [ Thu Jun 09, 2011 12:28 pm ]
Post subject:  low oil pressure

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 .

Author:  Paul I. [ Thu Jun 09, 2011 1:34 pm ]
Post subject:  Re: low oil pressure

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

Author:  Aussie_Horizon_190 [ Thu Jun 09, 2011 6:10 pm ]
Post subject:  Re: low oil pressure

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.

Author:  powermaker [ Thu Jun 09, 2011 8:16 pm ]
Post subject:  Re: low oil pressure

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 .

Author:  Aussie_Horizon_190 [ Thu Jun 09, 2011 9:26 pm ]
Post subject:  Re: low oil pressure

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.

Author:  jvthundercat [ Fri Jun 10, 2011 8:51 am ]
Post subject:  Re: low oil pressure

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............ :lol:

Author:  pet575 [ Fri Jun 10, 2011 12:05 pm ]
Post subject:  Re: low oil pressure

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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