MG Car Repair: 78 MG B Oil Pressure gauge not working at all, oil pressure gauge, hydraulic gauge

Question
Hello,
I bought this car last summer and am really not sure if this gauge was every working now?   Not sure where to start to troubleshoot.  

Someone has looked and there is oil (via the cap on top of the engine) being distributed when the engine is on.  I was told this should be very visible, not just 'wet' looking.

Again, I'm not sure if this is a recent thing as I just noticed the fuel gauge has started to be sporadic - sometimes registers correctly then stops all together.

Thanks for your patience

Answer
Hi Rae,

Oil pressure to the bearings is the same as blood pressure to your body. If you were to loose oil pressure while running the engine, major damage occurs in seconds. So it is very important that oil pressure be maintained at ALL times.

Any time I get a car in the dealerships I worked in that had low or no oil pressure I connected a known good hydraulic oil pressure gauge in place of the connection at the engine block to confirm the reading. (The 78 came with a hydraulic gauge in the US) Most auto parts stores sell a hydraulic oil pressure gauge to use for testing and it usually comes with several types of connectors.

If I see low pressure or no pressure I first look at the oil pressure regulator valve in the block. If the regulator valve is correct and the spring strong I would need to remove the pan and plasti-gauge the rod bearings to see the oil clearance as that is what causes oil pressure. If the clearance it excessive oil flows through and no pressure is built up. If the bearings are correct (from .0015" to about .002") then oil can not go through the bearings rapidly and thus pressure builds up to about 35PSI at idle and 45 to 70PSI at cruise.

The oil pump has the capacity to pump over 400 PSI so a pressure regulator adjusts it down. A stuck valve or a broken spring in the regulator can cause a loss of pressure.

There are other causes but are rare. A stopped up pick-up screen on the pump of loose bolts that secure the pump.

A oil pressure test with a known good gauge is the first step.

Howard