C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

Replacing oil pump

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Old Jun 29, 2005 | 12:11 PM
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Default Replacing oil pump

I'm tired of looking at extremely low oil pressure readings in my otherwise well-performing '89 L98 coupe. I intend to have it for quite awhile and use it as a daily driver, so I think I'm going to replace the oil pump.
What is a good brand and are there any particular problems I should lookout for.
I know alot of people on this board are content with low oil pressure, but if some guys can say they don't have it, that tells me there's a fix.
My car is stock with 110K miles, no smoke or oil consumption, runs fine, will run very (220-230) hot in traffic. Am thinking of adding a temp-chip to help overheating problem.
Any suggestions?
Thanks
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Old Jun 29, 2005 | 12:43 PM
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Melling M-55A pump is what you want, assuming your sending unit is good.

First step though would be to replace the sender and probably put a new connector on it. Its necessary to remove either the wiper motor or distributor cap to get to it.
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Old Jun 29, 2005 | 03:01 PM
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Done that.
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Old Jun 29, 2005 | 03:47 PM
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It would be VERY unusual for the pump to be the cause of low oil pressure. Electric gauges aren't all that accurate. First I would verify the accuracy of the car's gauge by comparing it to a known accurate mechanical gauge. If the gauges compare, then I would suggest trouble shooting for the cause of the low oil pressure. The pump is responsible for no more than 10% of the pressure reduction, if that.

RACE ON!!!
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Old Jun 29, 2005 | 09:00 PM
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is it low all the time or just after its warmed up? is it low just at idle, which is normal since SBC don't require alot of perssure at idle. but if you have good oil psi when engine is cool and not when warm thats a sign of other bad things, i.e. main bearings going?
whats happens if you put in a thicker grade oil? some to try.
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Old Jun 29, 2005 | 09:18 PM
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i had low oil pressure when i bought my vette. i pulled the oil pan and found chunks of plastic off the stock timing gear in the pump pick-up. replaced the pump while i was there.

frog.
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Old Jun 29, 2005 | 10:06 PM
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Originally Posted by CFI-EFI
It would be VERY unusual for the pump to be the cause of low oil pressure. Electric gauges aren't all that accurate. First I would verify the accuracy of the car's gauge by comparing it to a known accurate mechanical gauge. If the gauges compare, then I would suggest trouble shooting for the cause of the low oil pressure. The pump is responsible for no more than 10% of the pressure reduction, if that.

RACE ON!!!
I've found worn bearings to be the cause of low oil pressure much more often than just the pump. After verifying actual pressure (as previously stated with a mechanical gauge) pull the pan and check everything. A new timing set is not a bad thing to replace in an older engine as well to help it run like new again. If you find any plastic debris in the pan, check the valve seals as well as the timing set.
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