Why does oil pressure drop..???
- Thread starter bobpo
- Start date
as the motor warms up so does the oil, when cold oil is fairly thick, when hot it gets thin, thin oil runs out of the clearances on the mains and crank eadier and faster than thick oil, try pouring stp out of a can when cold, then warm it and try again, you will see what in talking about
hardtimes
Well-known member
Bobpo,
Fairly simple formula, IMO...i.e.- as heat (engine) goes up, viscosity of oil goes down!
Aerocraft
Well-known member
There is no "cap" on the pump. The oil only has to go a short way, up the pump, turn a corner and quickly gets dumped into the valve chamber. From there it is gravity and splash that delivers the oil. Once the viscosity drops, pressure drops but volumn stays high. Gar Williams
2manycars
Well-known member
There is no pressure regulator on a model A pump, as it is not intended to create pressure, but volume. The pressure you see is from the friction of the cold thick oil against the passage up the pump body and into the valve chamber, where it dumps out. As the oil heats up, it gets thinner and so can flow easier, and so the lower (or no) pressure reading. An oil guage on a model A only proves the pump is still running, nothing more. The oiling system on a model A is gravity feed to the main bearings and cam bearings, and splash to the rod bearings and pistons. There is no pressure designed into the system.
Mike V. Florida
Well-known member
Three pounds seems like alot in a normal A.
Terry NJ
Well-known member
My Ford 8N (1952) tractor (4 cyl, flathead) would start at 40 lbs, cold and go zero by the time it was warm. The first time, I went into a panic until a friend told me it was normal. Some "Normal"!
Terry
Terry