oil pressure low?

[72velle]

this place has really helped me out. im hoping for some good advice on this problem. i own a 72 velle. my oil pressure goes up and down a lot. when the car gets started it wont go above or below 60 psi. but after the car warms up when i come to a stop it drops slowly and as days go by, it drops more and more. i have come to a stop and had it drop down close to 10 psi!! once the car stops completely it raises back up, but sometimes raises to about 40-50 psi. when i start driving it goes back to 60-65. i am worried about this problem. i do have a small leak but nothing crazy. i bought a new high volume oil pump, but if it was the pump wouldnt it just be bad all the time. like i said, it holds good psi when cool. when it warms up its good too, but when i come to a stop, it drops dramatically. any help would be appreciated.

[68chevelle]

well, it doesnt really sound like you have a problem, but the way you said it made it kinda confusing to me. personaly, when i start my car, when its cold, it will be at about 40-45psi sitting there, and then driving its around 50psi. now when it worms up, sitting there it will be ussualy around 15psi, but on a hot day it is not unusual for it to drop to 10psi. and then when im crusing it will climb to about 40psi. oil pressure is dependednt on.... heat of the oil, the kind of pump you have of cousre, RPM's, and the weight of oil you are running, oh and also weather your low on oil or not. all of those things will cause the oil pressure to change.

[72velle]

well i am using 5w 30 so it is normal for it to drop that low? when it drops that low it sounds like the motor is going to die. how do i raise the psi. i am putting in the high volume pump this weekend. will that keep them higher.

[molehole]

I would run 10w30 in it. It is a little thicker and might protect the engine better. I run 10w30 synthetic blend in my 71 monte carlo and it sits at about 40-50psi cold and around 20psi or so when warmed up. My engine has 161,000 miles on it and has never had a rebuild so I must be doing something right. Or at least the owners that had it before me. Good Luck

[72velle]

ok, ill run the 10w 30. but just to clarify.....its ok for the pressure to drop and raise so dramatically? it runs at 60-65 and idles at 30. i just want to make sure thats normal. if i need to make a sudden stop it drops down to about 5-10 psi and i have to drop it into neutral and it raises back to normal. but that is only when i have to make a sudden and quick stop.

[molehole]

The oil pressure will move around when you come to a stop. As long as it is not fluctuating like crazy at cruising speeds it sounds like it is fine. Is your engine rebuilt for performance or is it basically stock? Sometimes that can make a difference. If you rebuilt the engine and have always run 5w30 in it I would stick to it. As the engine ages it grows accustomed to certain types of oil( bearing tolerances, other wear and tear) and I would stick with it. If it is a stock engine, chances are it probably has always had 10w30 or 10w40 in its lifetime. 5w30 just gets the engine oil faster when it is cold then say 10w30 because it is thinner when cold. WHen warm it has the same viscosity, hence w30. If you live in a cold climate during the winter(below 32F) and you are driving the car everyday, 5w30 would be best. Ifin say Florida it really doesn't make that much of a difference. Hope this helps.

[JohnnyR17]

Dont change that oil pump!
Youd be doing a whole lot of work for nothing.

10psi at idle is acceptable. Chevrolet engines, both big and small block have excellent oiling systems. 5psi will get you down the road.

Since you have great pressure going down the road and plenty at idle in park, there is nothing seriously wrong with your engine,, especially with relatively thin 5-30 oil.

You stated 'When it drops this low it sounds like the motor is going to die.' The problem here is your idle speed is set just a bit too low.

Heres how to fix it!
Warm up the engine,
Adjust your idle screws out in "half turn" increments until it idles in gear without feeling like it is going to die.
All you need to adjust idle screws on any carburetor is a screwdriver.
On a Quadrajet, the screws will be in the front of the carburetor (towards the radiator). They look like little screws with springs around them.

This is very easy to do and I can almost guarantee it will fix your problem and your oil pressure will be normal again!

[72velle]

thanks ill check that out. do i need to adjust the screws on the carb with the springs or just the throttle screw on the side?

[molehole]

Do you have an idle stop solenoid on your car? (looks like a cylinder with a plunger sticking out of it) If so that could be not working properly. First let the car warm up fully and then adjust the throttle screw on the side till it revs at like 800-1000 RPM's or so. That should do the trick

[molhannah]

It won't hurt to check those screws with the spring (idle adjuster) after you check previous statement. After engine is warmed up and chock is off, turn screws in slowly until engine RPM drops, then back out until highest idle is found, then same on second screw. Good luck.

[fla1976]

I would check the gauge itself. Install a mechanical and confirm that the pressure is actually low. If it is low then I would pull the oilpan and check the screen on the oil pickup. It could be clogged and dropping the oil pressure. Though the SBC has a good oil system, I would be a little nervous with 10 psi oil pressure. Low oil pressure is rough on rod and main bearings. fla1976

[molhannah]

I think his problem has been solved, seeing how it was over two years ago.