how much oil pressure?

[htchevyii]

Those of you that have functioning gauges, how much oil pressure do you have? I freaked when I fired the 1438 last night and only had 10 lbs oil pressure. I hooked up an aftermarket mechanical gauge and had 40 psi @ idle and 50@ 3k. My '82 just has an idiot light, so I was wondering what is normal? The engine is fresh, but the oil pump is used, (inspected and measured, but used). thanks!

[manoa matt]

Thats a hard one to answer. Kind of like what is the normal opperating water temp. Oil pressure will depend upon several factors, The pump condition, tolerances, and spring. The condition of the engine and how "worn" it is. What grade and viscosity of oil. The oil temp is a big factor. You'll notice oil pressure drops as the oil heats up. Possibly the size and capacity of the filter.

As a general rule: Fiats will show almost no pressure at idle when fully warmed up with the stock electric gauge. Figure about 10 psi for every 1000 rpms. Ideally you would like between 65-80 psi around 4500 rpms.

A mechanical gauge with the capilary tube will always be more accurate than the stock gauge with the electric sending unit. The disadvantage of the mechanical gauge is, if the tube breaks you got hot oil spewing in your cabin. Plus it looks different than all the other gauges.

I installed a mechanical pressure gauge after rebuilding the engine to get accurate readings. Once I was comfortable with it and knew the various pressures durring different driving conditions I re-installed the stock pressure gauge to match the other existing gauges.

[So Cal Mark]

many of the oem oil gauges read inaccurately

[mdrburchette]

My rebuilt 1608 was showing low oil pressure until I installed a mechanical gauge, then it was showing 50 lbs at idle and 80 at higher rpms. I changed the oil pressure sending unit and it caused the oe gauge to read correctly for quite a few months.

[mbouse]

interesting post, with several adding just a bit more to complete the total picture.
stock gauges are notoriously inaccurate
mechanical gauges are not stock looking
electrical sending units vary widely in accuracy (i tried three before i could get one to make an OE gauge work)
many factors other than gauge equipment lead to pressure reading


the funny thing is that most of us don't have a gauge to begin with, and suddenly become concerned when we first install a gauge (i did).

the best thing to consider is, over time, look for drastic changes. that OE gauge will eventually become a familiar reading, and BIG changes in its output won't be a normal thing. when BIG changes are seen... then panic. also, don't abandon that little red light. it is always accurate. if it is on, you are in big trouble.

[Europa]

I was/am looking into this issue as well. My gauges are metric; I believe the center hash mark shows 4 bar and the high shows 8 bar. When the engine is cold (and running ) the gauge shows about 3-3.5 bar. Once the engine is warm the needle is very close to 0 (zero) bar when the engine is idling. The needle does move when the engine is revved.

I was planing to clean all the contacts and remove, clean and reseat the sending unit. I wasn't overly concerned as the gauge also has an idiot light that comes on when the ignition is turned on.

I am interested in how to "improve" the accuracy of the gauge as well.