88 Firebird 305 Oil Pressure Issue - Please Comment

First off the car is a 1988 Firebird Formula 305 Vin Letter E. I've picked up a new oil pump but when I printed out the repair specs I've decided to try and get some input from the web.
I'm having an issue where on startup cold I'm getting around 30 psi and that stays pretty constant until engine warms up, then I start to lose oil pressure and eventually at idle it completely drops to zero. When I am driving I get about 15 - 25 psi but if I come to a complete stop or slow down to a crawl I lose complete oil pressure and then I get a knock that scares me. The only time it knocks is at idle or driving really slow with no oil presure. I've decided to not drive it until I'm sure what can be done to help the issue. I am running 10w30 and I believe the oil type isn't the issue. I'm afraid the oil pump might be going out. Is there any other options that might be the issue before I have to start the long process of changing the Oil Pump. Like maybe a faulty pressure relief valve or a sending unit?
Thank you for your input
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The engine per vin is E = 305 ci V8 LO3 (1988-1992) If this helps.
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snipped-for-privacy@gmail.com writes

shells. And possibly other things that you will find when you get inside the engine.
--
David Toft

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I'm getting oil pressure when I drive and when I setup on the break and give it gas in gear I get oil pressure.
Would that still fall under crank? I'm not so sure.
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Kind of sounds like worn bearings to me, too. Change your oil and put some straight 30W in and see if your pressure goes up. Or try some a little heavier. Do you have to pull the engine to change your oil pump? I would have to on my '74. In any case, if you change the pump, you can always plasti-gage your bearings to see where they're at. HD
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yeah I have to pull the starter, exhaust, undo the engine mounts and lift the engine about 6 to 8 inches. I'm really debating the oil pump replacement because people are telling me that it might be the bearings... In that case I might as well buy a rebuild kit and redo the engine. I just do not want to waste my time putting in a pump if thats not gonna help the issue.
I hope I get some more comments on this post.
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Imagine that the oil pump is the most lubricated part in the entire engine. Other than the relief spring stuck open (i have seen this & results in No or little oil pressure even at startup) i suspect the bearings are heavily worn. These can be replaced from underneath (seeing as you have to lift the motor to get the sump off) just replace 1 at a time & retorque the caps.
I did have a ford 351 Cleveland that ran several years at about 5-15 psi idle. it actually died by the piston splitting & going through the block.(so its a ford - who cares) :->
--
Mitch - 1995 Z28 LT1 M6
terminal snipped-for-privacy@sand-hill.freeserve.co.uk
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The bearing are trash, You may be able to replace the bearings depending on what the crank looks like or Put some 50 wt oil in it. It come down to the fact you need a new engine
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I put 50w oil in it and the pressure issue has not changed.
It gives me alittle longer time before the oil pressure drops to zero.
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Its bearings...period. classic symptoms and that engines junk from day one from the factory....
Sooo......
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Take that back ! :-) My 305 i had fitted in my '78 Camaro (replaced the 6 pot) was very sweet & smooth. I replaced it with a crate 350 4 Bolt which just never did run right. The 305 (stock cam) averaged about 28 MPG cruising at 90mph and ran high 16's. I could drive all day on a tank of gas!
--
Mitch - 1995 Z28 LT1 M6
terminal snipped-for-privacy@sand-hill.freeserve.co.uk
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aka-SBM wrote:

point of actually getting real performance out of it, properly taken care of they get good economy, ok performance for the timeframe, and last decently. That said, you have it on the nose, the bearings are clearly gone on that puppy.
--
Cy Welch
89 Camaro RS 5.0 TBI
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Thanks guys now I need to decide if I'm gonna rebuild the 305 or the 327 my old man gave me.
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wrote:

That's a no brainer since they will cost the same to rebuild. Take the one with the better bore and stroke ratio and more potential. The intake and peripherals will fit on the 327. The only thing you should have to change is the valve covers and maybe elongate a couple of bolt holes for the intake. Get a book on rebuilding the small block Chevy, well worth the read even if you are going to farm out the work.
...Ron -- 68'RS Camaro 88'Formula 00'GT Mustang
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Thank you =)
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I call em junk cause I got one..LOL
Heads make GREAT boat anchors.
LOL

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