I have a 1993 chevrolet truck with the 350 when its cold it has good oil pressure but when it warms up its bad the needle is just a lil above the red what should i do?

Check the coolant temperature sensor. A bad sensor will cause a very rich fuel mixture not allowing it to start.

THis is the classic symptoms of either a clogged oil screen or a bad oil pump. When the oil is cold (thick) the system is easiest to reach the required pressure. As the oil warms up (thinner) it is difficult to maintain the pressure. Try flushing the engine oil and putingin new oil and filter. THis may solve the problem...if not, look to change the oil pump. Goodd luck..

When the engine and oil are cold it will show a high pressure because of the viscosity of the oil. When it warms up the oil is thinner. If it doesn't drop below 20-25 psi at warm idle I wouldn't worry about it as that is normal.

how did you clean the gasket off of the head? if you used a sanding disc the grit will eat up the bearings. are you reading pressure with a mechanical gauge? you have replaced all bearings??

6 psi @ 1000 RPM
18 psi @ 2000 RPM
24 psi @ 4000 RPM
this is chevrolet specs on oil pressure in your truck so you are within the range.

describe your idle problem more and i will try and help you with that

Sound like a posible bad oil pressure sending unit . It is normal for pressure to be above normal just after starting . At a cold idle , the oil viscosity is higher than it would be if it were warm . If the guage is reading really high for longer than normal ( after 1 minute of cold idle ) then I suggest having the sending unit checked .A sevice center can check the sending unit on or off the vehicle as well as checking pressure with an actual guage for more accurate readings .

It sounds like oil pressure switch is bad. You said you changed? To clarify, your oil pressure switch is also a safety item that shuts down ignition when oil pressure drops. Try an oil pressure gauge (hand held) to relieve your nerves about engine seizure. Make sure you're not getting to much fuel in engine also, that will dilute oil to a thin viscosity and show low oil press.

Depends on which pan it has,you may need to unbolt motor mts and lift engine up a couple inches to get it out...

sorry to say that low oil presser after warm up is most likely do to bad main bearings. if other wise it is in good shape i would replace main& rod bearings and oil pump.can do it your self for a few hundred,if you would like any further assistance feel free to ask, thank you for using fix ya.

WHEN COLD THEN GOES AWAY WHEN WARM. THATS NORMAL FORGED PISTONS SLOP WHEN COLD.I HAVE 01 SILVERADO WITH 390,000 RUNS GREAT 21MPG 40TO50 PSI OIL PRESSURE KNOCKS WHEN COLD THEN GOES AWAY. NOT A PROBLEM. IF IT DOSE IT WHEN WARM AND LOW OIL PRESSURE WORN BEARINGS NOT GOOD.

remove the oil pressure sending unit and check the oil pressure with a pressure tester.Let it warm up.If the pressure stays above 6 psi then replace the sending unit.Hope this helps.Good luck.