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Took Sophie out this morning for a short drive as it's been too hot lately to drive her. Again 1929 Club Sedan 633, restored 22 years ago. I did get the springs issue resolved BTW.

Odd thing this morning, oil pressure was normal when she was cold, 40 psi pushing to about 45 at speed. On way home (10 mile trip total), she was running happy at 170 degrees, but I noted the oil gauge was actually going UP to 50 psi at idle, but revving the motor the psi went DOWN to 40 and at speed she was usually at 40 psi. The opposite of what I've usually seen to be the norm - once warmed up, the gauge reads higher at idle than at higher rpms.

I'm in Louisiana, it's darned hot down here, longtime user of Lucas 30 weight oil with the high zinc content. All my old cars have always seemed to love this stuff. Changed the oil and cleaned the screen and such last August, about 500 miles ago.

Any ideas? Thanks!

How is the oil level?

Gauge is slightly below full. Maybe 1/2 a quart low. Just went and looked. Will add some before next trip.

That's a weird one. Perhaps try hooking up an aftermarket gauge. Or test 20 weight oil because there might be some foaming action going on. There also is that feed valve to the pistons that might be causing a problem. The oil feed to the cam is taken off the rear main and that is where the gauge tap is. Another possibility is there is something floating inside the oil pump screen that rises when the oil gets turbulent.

Hopefully somebody didn't tamper with that gauge to make it read high. So the first thing I would do is test an aftermarket gauge.

If the oil level is too high, the crankshaft counterweights are beating air bubbles into the oil. During high rpm runs the oil is getting aerated faster. Once air bubbles are present in the circulating oil, the oil becomes "compressible" and the pump looses efficiency.


When you slow down, the air floats to the surface and the oil loses its compressibility and the pressure rises.

I'd try dropping the oil level 1 quart and do a short repeat just to see if it is the problem.

1929 Packard Guy,

You must have resolved the issue by now. What was the answer?