Disco 1 No oil pressure

I went to work and the Disco was running normally, at lunch time I started up and I had lost my oil pressure. I removed the switch and with the engine running no oil came out. I have removed the sump and the strainer is clear. What do I look at next? Has the oil pump failed? My disco has only done 195000 miles so it should know better.Paul

Oil pump, stuck release valve, blocked filter

Paul Bernal Ryan said:

My disco has only done 195000 miles so it should know better.Paul

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What engine are we talking here?

Hi Gazbo.The engine is the 'bullet proof' 300 tdi.

Paul Bernal Ryan said:

The engine is the 'bullet proof' 300 tdi.

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So, this engine was running ok, with oil pressure, then next start it had no oil pressure, or in fact flow, because if you screw out the oil pressure switch from the block there should be something.
The oil pump of a 300Tdi engine is on the front end of the crankshaft direct so I see no way it could stop turning, unless the key or whatever drives the pumping element around has failed. The oil pickup from the sump to the internals of the pump is through a pipe with strainer, that you have checked, there is a possibility that the suction pipe has "o" ring sealed joint or joints on its way to the pump, if so, check these for integrity.
Have you checked out the entire suction pipe from strainer to the connection with the pump/block, any cracks, leaking joints will cause a loss of suction?
Is there evidence of oil in your radiator coolant, has the oil cooler circuit failed?
I think what has or is occurring is a bit unusual for this type engine, I have heard of Rover V8's, losing prime to the oil pump after an oil and filter change, but that I believe is a methodology issue, doing things in the wrong sequence.

I seen to recall there have been cases of the oil pick up pipe in the sump falling off, which will of course prevent the pump lifting the oil out of the sump. It may be worth having the sump off to check.