ive got a 89 350TBI. i noticed the other day drivin to school i only had 15 lbs of oil pressure so i just figure ok no biggy need to change the oil and my valve cover gaskets. get home do that everything seems ok. drive around and on the way home from school today i saw its right back down at 15. when i get on it itll push up to about 30 but nothin over unless im lucky. could it be my oil pump goin bad? and if so when i replace it do i need to buy a new pickup or can i reuse the old one
alright heres how it happened today. i cranked the truck oil pressure normal 35-40pds on the gauge. i drive it for a lil bit go get some gas and taco bell so probably ten minutes of driving. then the gauge drops to any where from 10 when im coasting to 30 when i was on the highway. and undernormal street conditions it was about 15-20. so i think the gauge is workin because it flucuates when i hit the gas let off the gas etc etc. but then would the oil pump work at first and deteriorate as i drove? but let me know what yall think it is based off what happened today
well as the oil gets hot it get thiner, so you will have less pressure
as a general rule of thumb you want 10 PSI of oil pressure for ever 1k RPM, so at 4K RPM you want atleast 40 PSI
the cheapest thing to do is change your oil again but put 10w-40 in it (which i would be running anyway on that motor) if that doesnt help try 20w-50
most likely the motor is just seeing its age, but you cant rule out things like the oil pressure sender intermittenly screwing up
I had a similar problem in my firebird, 92TBI. I had just put a rebuilt vortec 350 longblock in it, with a high volume oil pump. Took it for a couple drives around town, was fine. Headed on a long shakedown trip. About 30 miles out, my oil PSI started to drop. Started at 70 PSI cruising. Dropped to about 15. After i stopped and got gas, was back up at about 40, and dropped off again. When i got where i was going, it was down to nothing. But the engine was still nice and smooth and quiet. What i figured, and was right, the sender was failing. New oil PSI sender, and my oil pressure came right back to a steady 60psi.
I don't think it is to complicated here, if you start it up and your oil pressure is good and as the oil warms up and thins out you loose oil pressure, thats a pretty good indication that your crank bearings are getting to much clearance. As your engine warms up your bearing clearances get greater. Your engine is getting worn out. Replacing oil pumps or bypass valves is pointless, and by the way havin' oil leaks like your valve cover have nothin' to do with oil pressure.
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Related Threads
?
?
?
?
?
Pirate 4x4
18.7M posts
366.4K members
Since 2000
A forum community dedicated to custom off-road vehicle owners and enthusiasts. Come join the discussion about trail reports, builds, performance, modifications, classifieds, troubleshooting, fabrication, drivetrain, and more!