Picked up my car (1970 MGB Roadster, rhd) today and noticed a rather perculiar thing getting it home.
I was doing about 50 mph at the time and the oil pressure guage (direct read type) suddenly dropped, quite slowly, to zero.
There was no change in engine sound or revs/power and after I had stopped to check it over there was no oil leaks nor odd smells and the sump was full.
Later I unscrewed the union onto the oil guage capillary and checked to see if there was oil in it (there was). After resealing I restarted the car and was getting a 25 psi reading and the reading did not change markedly with revs.
Among other things the engine has been out for a replacement clutch and has been off the road for a major rebuild (body/paint) for about 9 months.
The engine was rebuilt about 18 months ago and the car has had limited use since.
Now is this as I suspect an air bubble in the capillary (ie guage problem) or something more serious (ie engine problem)
regards
Tom