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MG MGB Technical - Pulsing oil pressure gauge

71 Roadster. The oil pressure gauge on my car normally reads just below the 60 lb mark but never gives a steady read, it pulses between 55 and 60lb. is this normal or could something like an oil pressure valve be faulty.
Opinions would be appreciated. Trev
Trevor Harvey

Could be the oil pressure relief spring needs replacing. It's inexpensive but tricky to replace its retaining cap. Check archives on the best method to do this.
Steve Rechter

mine has always done this...I suspect air in the sender line to the guage...
P J KELLY

Mine too, for 25 years...Never under power...or at idle...then its steady...
Pete

Nowt to do with air, pressure is pressure. Some pulsing always occured, the factory modified the gauge with a sintered plug to try and mask it. Usually it only happens at certain temperatures and revs i.e. oil pressure and viscosity. You could try doing things with the pressure relief valve, but it is as likely to move it to some other combination of pressure and viscosity as do anything at all.
Paul Hunt

The pulsing is a feature of the pump - it delivers the oil in bursts - normally you don't notice the pulsing as the oil pressure relief valve dumps the over pressure oil and pulses in sympathy with the pump so leaving a steady pressure in the main gallery.

The sintered plug in the gauge deals with it pretty well when the engine speed is low enough for the OPR valve to shut completely at hot idle but you often see the needle pulse in the transition from hot idle to hot running.

A sticking OPR valve will also make the needle pulse but usually this are quite large fluctuations.
Chris at Octarine Services

Mine has always done this, years ago it bothered me and I tried a different RV spring, all it did was alter the pressure range when it happened, now I just accept it as one of the car's foibles.
Ron
R. Algie

This thread was discussed between 15/07/2009 and 16/07/2009

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