Oil pressure issue

[Ayoub]

Hey guys

i want to explain my problem , i have a very low oil pressure when i run my vette 84, it’s a carburetor not cross fire, when i start the motor, pressure is 30psi, after few minutes it’s going to decrease to 10 psi. I don’t know what’s the problem? Can you help me

Thx

 

[Rruuff Day]

Hey guys

i want to explain my problem , i have a very low oil pressure when i run my vette 84, it’s a carburetor not cross fire, when i start the motor, pressure is 30psi, after few minutes it’s going to decrease to 10 psi. I don’t know what’s the problem? Can you help me

Thx

Hopefully some C4 guys will chime in. Maybe @VikingTrad3r has some ideas.

 

[Dave91TM]

Hello Ayoub
From a quick search, the rule of thumb for oil pressure is 10 psi for every 1000 RPM. So if you are observing this drop at idle you are probably getting the higher pressure when the oil is cold and it drops as the oil warms. Not sure, without more details, of how and when you get the low pressure.

 

[Rruuff Day]

Hello Ayoub
From a quick search, the rule of thumb for oil pressure is 10 psi for every 1000 RPM. So if you are observing this drop at idle you are probably getting the higher pressure when the oil is cold and it drops as the oil warms. Not sure, without more details, of how and when you get the low pressure.

Thanks Dave. Forgot about you and the C4. So use to you being a 58 sedan expert....

 

[Dave91TM]

Thanks Dave. Forgot about you and the C4. So use to you being a 58 sedan expert....

My expertise is defined as knowing a little bit about everything and a whole lot about nothing. I'm just very happy there is no chrome trim on a C4.

 

[Murray20c8]

My expertise is defined as knowing a little bit about everything and a whole lot about nothing. I'm just very happy there is no chrome trim on a C4.

Hey Me too! Welcome to the MensAss club!

 

[LE BARON]

10 PSI "might" be a problem if you have an extended idle period with the engine hot.
Seems like the drop occurs not long after you start the engine. So an extended idle like when caught in traffic after a long run merits monitoring the pressure.
If it drops below 10PSI I would be worried about lubricating the top end.
Make sure you have the right grade of engine oil and always remember the "KISS" principal. You check the easy things first.

 

[Ayoub]

Hey guys, sorry for my late answer. Just to know i have a leaking oil. So when i run it the oil pressure show 16psi then decrease to 0 slowly and then engine stop.
I keep restarting many time until it’s warm, then i drive it out the garage, after 1 or 2 minutes engine stop while I’m driving! The steering wheel is blocked, i run it again, always the same case!! From 16psi to 0 then engine stop. Someone who has a c4 told me to change oil to 20w50 and see if the pressure go up, that’s mean the engine is tired i did it, but nothing changed.. I don’t know what’s the pb.. I’m wondering to change the oil pressure switch or sensor! What do you think?
Thank you

 

[LE BARON]

If you are dropping to 0 PSI you either don't have enough oil (doubtful) or you have either an oil pump problem or a lub leak someplace in the engine. 16 PSI at startup sounds pretty low to me.
I would presume that you changed the oil/filter when you bought the car.
If you go to a higher viscosity oil it might help in the short term.
Sounds like a winter project.

 

[Ayoub]

10 PSI "might" be a problem if you have an extended idle period with the engine hot.
Seems like the drop occurs not long after you start the engine. So an extended idle like when caught in traffic after a long run merits monitoring the pressure.
If it drops below 10PSI I would be worried about lubricating the top end.
Make sure you have the right grade of engine oil and always remember the "KISS" principal. You check the easy things first.

What’s the kiss principal?
I had 5w30 synthetic, but now i changed it to 20w50

 

[Murray20c8]

What’s the kiss principal?

Keep It Simple Stupid

 

[Dave91TM]

Here is the page from the GM Service Manual re: Low Oil Pressure. Hope it helps. From your latest description it may not be good but, don't panic and keep looking for something simple first.

 

[Ayoub]

Thank you i’ll check it. I already bought an oil pressure switch and filter to change. I’ll let you know

 

[VikingTrad3r]

Hey @Ayoub did you figure this out?

 

[1st Vette]

What’s the kiss principal?
I had 5w30 synthetic, but now i changed it to 20w50

Could be the sending unit.

 

[Ayoub]

Hi, i order the oil sender unit and the EGR Control Valve Relay Solenoid and i'm waiting to receive it and replace them. i'll let you know if problem is solved.. otherwise it must be an issue in the oil pump !!!

 

[1st Vette]

Hi, i order the oil sender unit and the EGR Control Valve Relay Solenoid and i'm waiting to receive it and replace them. i'll let you know if problem is solved.. otherwise it must be an issue in the oil pump !!!

It’s like most problems. Replace enough parts and eventually things work again. I hope you don’t have to go that far. Good luck with it. If it is the sending unit your pressure may be fine but until you know for sure maybe drive another vehicle till you sort it out. Just a thought but if you have nothing better to do maybe you could remove a valve cover and start the engine to at least see if you’re getting oil up to the valve train . Should be pretty wet in there.

 

[Ayoub]

Thank you my friend, i hope it will be fixed well
Of course i have my 2nd car . I’ll fix it and just test it to see. To drive it , it will be next April after the snow