Oil pressure . . . normal?
 

Installed a new Marshall oil pressure gauge. There may have been another inside gauge at one time but all there was before this installation was a plug in the block and some old tubing running through the firewall. I was curious if 3 psi at idle could be considered normal. Rev'd the engine up some and got her to six psi. Thanks in advance.

Re: Oil pressure . . . normal?
 

Yes, that is normal.

Re: Oil pressure . . . normal?
 

It is not a pressure pump it is a flow pump. My suggestion is take the gauge off and plug the hole. All the pump does is move the oil from the pan to valve chamber on a stock engine. The pumps are very robust so unless it gets plugged with gunk in the pan or has a major catastrophe, they just keep doing their job. :) Oh and check the oil level from time to time.

Re: Oil pressure . . . normal?
 

I think it is reassuring to know that the oil pump is working even though there may not be much indication after the engine warms up.

Re: Oil pressure . . . normal?
 

pressure? yeah you want some pressure..... ha! I think mine just likes the 6 but yeah thats probably fine. looks funny on my gauge that tops out at 5.

Re: Oil pressure . . . normal?
 

As mentioned above it is a good idea to use a gauge even though pressure is low...

1. Whenever you remove the oil pan for any reason it is good insurance to remove the four bolts on bottom of oil pump and clean the filter screen.


2. The 1932 service bulletins mention that a plugged filter screen was found to be the major cause of MANY failures of engines sent to Ford rebuilding facilities as cores!

Sludge in engines from infrequent oil changes will plug the screens.

3. Timing gear failures with fiber gears will plug the screen with debris...

Re: Oil pressure . . . normal?
 

The valve chamber is vented to the atmosphere via the crankcase, so once pumped oil reaches the end of the tube in valve chamber, its gauge pressure is zero.

Oil pressure between the oil pump gears and its passage to the valve chamber is due to the pumping head, a gravity head, the oil's viscosity and the dynamics of flow in a pipe. This pressure is relatively low, typically below 10 psig.

The oil pump's principal function is to deliver enough volume of oil to keep the valve chamber dams full. Oil flow to the engine's main bearings and end camshaft bearings is due to gravity and the dynamic action of the journals spinning in their bearings.


The center camshaft bearing oil supply is pressure fed by the oil pump.