[Omatako]

Yes the decreasing oil pressure has been a long running mystery. It starts out at 50 PSI, the gradually drops, but never so low as to sound the alarm. It has done this for the past 2 years, possibly longer.

It's probably not as much of a mystery as you would think.

IMHO it is probably nothing more than a failing oil pressure sender unit. This is quite common - I have had it on my own boat and recently had exactly the same thing on the wife's car. On the boat it went on for a few years getting gradually worse. On the car it went from normal to "no pressure" in about a month.

As the engine warms up the resistance in the sender changes and indicates lower and lower pressure but never sets off the buzzer. That's because the buzzer has its own sender and doesn't use the signal from the gauge sender so is sensing the "real" pressure which is probably normal.

For the cost of a new sender unit, the peace of mind is worth it.

 

[Omatako]

Also, a mechanical gauge should be fairly reliable.

Paul T

Yes it would but that's a whole new project . . . . where would I put one on my boat? Don't actually know.

 

[Omatako]

I have installed a steel "T" fitting in the original sender hole, one side for the electrical sending unit, the other side for the small, what appeared to be plastic or nylon, hose that went to the mechanical gauge.

Or, one could just temporarily hook up the mechanical gauge to verify the accuracy of the electric gauge.

IIRC, I think I have read about mechanical & electric gauges operating on one sender.

Paul T

Hey Paul, without wanting to pull the ring out of this, it's not about the connections to the engine, that's the easy part.

It's about where to put the gauge. It's not going to fit the original panel - or let's say it certainly won't on a Yanmar panel, maybe it will on a Universal's panel.