Oil Pressure Concerns (again)
04-18-2007, 09:02 PM
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Oil Pressure Concerns (again) I know this topic has been kicked around here many times, but need to bring it up again for my own peace of mind. just started running my fresh (new cam, main and rod bearings, oil pump) '94 LT1, it's in a '57 Chevy. started it several times for short periods, just to hear it idle. Now that I have finished
doing the cooling system and filled with straight water (for now), I've been able to let it idle for longer periods, long enough for it to go into closed loop
and the idle speed to drop.
Previously, in open loop my Dakota Digital gage stayed between 60 and 70 PSI, I was happy, thinking all was healthy, and my assembly was correct.
Now, once it has warmed up and ilde has dropped to about 800 RPM, the oil pressure is flashing 6 PSI. there is no top engine rattle as I would suspect when running that low pressure for 30 minutes. Put a mechanical gage on it and it does improve to about 18 PSI, thats not as bad ,but it's a new engine!, why do these LT1's run at such a low PSI? When I give it throttle it climbs up as normal engines do.I have checked GM specs, they do say 6@1000, but that is a MINIMUM, a fresh engine shouldn't be that low.
I have always used a PF35 filter on all my engines, went to the parts store and compared a PF35 to the recomended PF454, the 35 has only about half as many oil passages in the top of the filter, I bought a 454 and will install it,
perhaps it will improve.
I'm not planning on keeping this car for long, how do I tell a prospective buyer, when he see's 6 flashing on the oil pressure gage that it's normal.
Thanks...
doing the cooling system and filled with straight water (for now), I've been able to let it idle for longer periods, long enough for it to go into closed loop
and the idle speed to drop.
Previously, in open loop my Dakota Digital gage stayed between 60 and 70 PSI, I was happy, thinking all was healthy, and my assembly was correct.
Now, once it has warmed up and ilde has dropped to about 800 RPM, the oil pressure is flashing 6 PSI. there is no top engine rattle as I would suspect when running that low pressure for 30 minutes. Put a mechanical gage on it and it does improve to about 18 PSI, thats not as bad ,but it's a new engine!, why do these LT1's run at such a low PSI? When I give it throttle it climbs up as normal engines do.I have checked GM specs, they do say 6@1000, but that is a MINIMUM, a fresh engine shouldn't be that low.
I have always used a PF35 filter on all my engines, went to the parts store and compared a PF35 to the recomended PF454, the 35 has only about half as many oil passages in the top of the filter, I bought a 454 and will install it,
perhaps it will improve.
I'm not planning on keeping this car for long, how do I tell a prospective buyer, when he see's 6 flashing on the oil pressure gage that it's normal.
Thanks...
04-19-2007, 02:32 AM
#6
20 psi at idle is fine. you really only need about 10 psi per 1000 rpm to be good.
As for the Dakota Digital and a new buyer... if the gauge reads incorrectly - which it does as evidenced by mechanical gauge - either it's installed wrong or the sender is defective. Check install, and return defective.
As for the Dakota Digital and a new buyer... if the gauge reads incorrectly - which it does as evidenced by mechanical gauge - either it's installed wrong or the sender is defective. Check install, and return defective.
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04-19-2007, 08:07 PM
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I used a stock Delco oil pump, The engine only had 43K on it, so just polished the crank, and replaced all bearings with stock size, nothing over sized. Plasti gaged all during assy. The straight water was only used to check for leaks, didn't want to spray sticky coolant all over the billet.
