Hello
I have a 1974 XJ6 4.2L which has done only 26,000km, it has been started regularly with no oil pressure issues. I had been trying to install a security alarm & central locking. (Another story) I just finished reinstalling the dashboard black leather top the day before.

I started the engine to give it a run. To my horror the oil pressure warning light stay on & the oil gauge read zero pressure.

When last started last week the oil light went out immediately & the oil gauge needle went past halfway.

Earthed out the gauge wire & gauge needle headed towards 80psi & removed oil pressure warning light wire and light went out

Checked the oil dip stick & oil level was spot on. Oil & filter have done less then 100km.

The few seconds that the engine was running there was no indication of no oil, like the first start after doing an oil change.

I am at a loss of what to do next and I am going into hospital for a shoulder replacement on the 15th May, any help would be match appreciated

 

Remove the oil filler access cap and start the engine. You should see oil flowing through the camshaft area.
If there is oil flowing through the camshaft area then that is OK and you have a gauge/light problem.
If no oil flow then you have an oil pump problem.
Don't run the engine for more than a minute if no oil flow.!
I trust the shoulder replacement goes well.

 

Buy a mechanical oil pressure gauge, $30 on ebay to prove you have good oil pressure.
You have tested the gauge by earthing the wire and seeing the gauge moves. It then leaves a faulty sender or no oil pressure.