Oil pressure gauge reading high 4.2 engine

This weekend I took my 1977 S2 for a little ride.
After maybe 30 minutes of cruising, oil gauge was in the 80 PSi.
No abnormal noise from the engine, water temp was normal too. I did replace oil and filter last month.

Is there a way to determine if the culprit is an electric gremlin or if oil pressure is actually too high?

Thanks for your help!


I had a similar failure in my 1975 XJ6C last year. It was just the sender.

Mine is manual with A/C so I had an easy way to make sure it was just showing too much, as at idle when warm if the revs dropped a bit the yellow oil pressure warning light would flicker and the gauge still showed 60psi or more.

New sender unit and all is well again.
But I have heard many senders are bad to begin with. YMMV.


if you’re a bit of a non destructive tinkerer it’s worth investing (no great expense) in a couple of gauges that can be mounted in the engine bay, good one to have is a mechanical oil press/ gauge, vacuum gauge (removable) hand held laser temp sensor and so on

As Tom says, Romain - an external gauge, mechanical, will reveal the truth…:slight_smile:

Basically; the relief valve is there to prevent excessive pressure - but may (seldomly) fail. The pressure is measured after the filter, so changing filter will raise pressure a bit - but not to that extent.

Other scenarios may be imagined, but an electric gremlin is the more likely…:slight_smile:

xj6 85 Sov Europe (UK/NZ)

Thank you for your answers, I’ll add a mechanical gauge for peace of mind!

Just use the mechanical gauge for testing, Romain - then consider options…

xj6 85 Sov Europe (UK/NZ)