variable oil pressure

[Lotus 50]

Sometimes my oil pressure gauge shows the pressure varying up an down. Usually it holds very steady at a constant rpm.

Is the gauge the likely problem? What else could it be?

thanks

[rgh0]

The gauge should show a constant pressure if the oil pressure relief valve is opening. This is normally between 35 and 40 psi.

The valve is normally open when the engine bearings and pump are all in good condition and engine is hot and above idle speed. A hot engine at idle speed will normally see the oil pressure drop to the 20 to 30 psi range as the volume flow of oil drops and the relief valve closes.

If you can describe more about the pressures you see and in what circumstances they vary ( i.e. engine speed, engine temperature etc) then it may be possible to diagnose more about what is the cause. The gauge itself is a simple mechanical device and they are normally very reliable.

cheers
Rohan

[jono]

I had exactly the same problem with the electrically operated pressure gauge on my Plus 2.

I changed it for a mechanical gauge and the problem went away.

Jon

[rgh0]

I was assuming a mechanical gauge on an Elan but did not see
Lotus 50 = plus 2
yes maybe the electrical gauge !

cheers
Rohan

[Lotus 50]

It runs steady 35 at 4000 rpm except when it doesn't. Sometimes I get a small variation, 30-35, sometimes a bit bigger, 25-35, and sometimes real big, 10-35.

Usually it's steady, but it makes me nervous.

[richardcox_lotus]

Is that one of the guages controlled by the voltage stabiliser on a +2 ?

[jono]

I faffed about trying to get my electric gauge reliable and finally gave up. I am so pleased that I did - I now feel confident about the oil pressure. It was not nice seeing the gauge on a newly built engine, not even run in, showing anything from 0 to 5 to 80 psi depending on how it was feeling on the day

I obtained a second hand Smiths gauge of Ebay for ?15, painted the needle with Humbrol (they do a colour indistinguishable from the +2 orange, assuming you are not an early car) and swapped over the square edge bezel - looks perfect.

You will need a capillary tube and a 90 degree connector for the rear (no room behind the dash). I got these at a very reasonable price from Minispares (I have a 1966 Mini too )

It's your call obviously but I would not stick with an unreliable electric gauge if I were you

Jon