Oil Pressure Fluctuations

[Tim 7-33]

Morning all. I was out yesterday afternoon for a quick run up to the Yorkshire Dales. Warmed the car (500) thoroughly, first part of the journey some dual carriage way and sweeping A road, all fine. But then onto some narrower roads' say 45 minutes into the journey, single track in places, I noticed that the oil pressure had dropped from it's usual warm 35 psi to say 10 psi, then it would approach 0 psi, then back to 20 psi, then back to normal, changing pretty rapidly and continuously. At no point did the oil light come on, which is definitely working, and I was cruising, low revs, 2-3 gear. Obviously I stopped, checked oil level etc, checked the sender connection, all good. Re-started and pressure back to the 15-20 psi hot idle I normally see, rising with a gentle rev as expected. Coolant to level, fans working as expected, 78C otter switch fitted. Satisfied nothing terminal had occurred I drove home, similar symptoms, but when back in the garage idling pressure fine, level just below max, which is where it was before I set off. Engine oil tight. Pressure variation didn't seem to follow a pattern, so left handers, right handers, up hill, down dale, didn't seem to have an effect. Roads tight and trafficked so going very slowly to the point where I was happy oil surge wasn't an issue, if it ever would be on the public road. Has anyone come across anything similar? Have read tales of loose oil pick up pipes so dropping the sump to check an option but I would hope that's fairly low down on the list of possibilities. Maybe it's sender, gauge or wiring but obviously I don't want to damage the engine carrying out tests. I can source a mechanical gauge but static doesn't seem to be a problem and whether I can rig something up to be visible for a dynamic test I don't know. Any thoughts? Tim

[5.0ltr]

Happened to me a couple of times, both due to poor spade end connection to oil pressure switch, pulled off and cleaned fixed it.

[Sardonicus]

Dont ignore this as a loose oil pick-up pipe to block will do a similar thing (it happens) the oil light is little use IMO in this case they function @ less than 5-7 PSI oil pressure get a diagnostic oil pressure tester set to confirm that its not the above, not good but better than knocking out your crank bearings etc

[mjlloyd500]

Oil light comes on at 11 psi .I've had at least 4 new oil pressure switches and they have all failed at some point .Just get a new one fit and should be fine .I've had my car for over 20 years and 70000 miles

[Sardonicus]

mjlloyd500 said:

Oil light comes on at 11 psi .I've had at least 4 new oil pressure switches and they have all failed at some point .Just get a new one fit and should be fine .I've had my car for over 20 years and 70000 miles

That maybe but there is still room for accuracy fluctuations (different brands/quality etc) and even so I wouldn't want to be driving around @ 12/15 PSI for example either for the OP'er like I say get a diagnostic/mechanical set to check unless you like to gamble