The 59 AB in my '36 has always had good oil pressure. I run 20-50 oil and when the engine is cold the stock gauge was always pegged out until the temp got past 170 and then would read 35-40 psi at idle.
A week or two ago, the pressure showed 20 psi at any rpm when cold. No odd engine noise but it got my attention. I decided to do two things. I bought a really nice Autometer mechanical oil/temp gauge set. I found one that has a vintage look and the gauge faces are a similar color to the original. I also purchased a new sending unit for the stock 50 lb gauge. I put the sending unit back into the port at the rear of the engine behind the intake manifold. There was no room there to add a tee but I noticed a second 1/4 npt outlet oriented 90 degrees to the first one. I used it to mount the 1/8 inch tube for the Autometer gauge. When I started it up, I had 65 psi on the mechanical gauge and 20 psi on the original same as the original sending unit.
Must be the '36 pressure gauge, right? I lucked out and found a nice used gauge on eBay for a decent price. Got it installed and 20 psi just like before. I can switch sending units and gauges, still 20 psi. If I ground the wire to the sending unit, the gauge goes past 50 lbs.
As a final test, I used a 6 volt power supply to power the gauge, put an air hose coupling on the sending unit, ran a wire from the gauge to the sending unit and another to ground the sending unit (positive ground) Using the regulator on my air supply I put 25 psi to the sending unit. The gauge went right to midscale 25 psi. Both gauges and sending units did this. I could raise and lower the air psi and the gauges would go up or down.
I also moved the sending unit to the same port as the mechanical gauge, no change.
Not sure what the next step is. The oil pressure gauge and the fuel level gauge share the same power wire and the fuel gauge is working fine..............
A week or two ago, the pressure showed 20 psi at any rpm when cold. No odd engine noise but it got my attention. I decided to do two things. I bought a really nice Autometer mechanical oil/temp gauge set. I found one that has a vintage look and the gauge faces are a similar color to the original. I also purchased a new sending unit for the stock 50 lb gauge. I put the sending unit back into the port at the rear of the engine behind the intake manifold. There was no room there to add a tee but I noticed a second 1/4 npt outlet oriented 90 degrees to the first one. I used it to mount the 1/8 inch tube for the Autometer gauge. When I started it up, I had 65 psi on the mechanical gauge and 20 psi on the original same as the original sending unit.
Must be the '36 pressure gauge, right? I lucked out and found a nice used gauge on eBay for a decent price. Got it installed and 20 psi just like before. I can switch sending units and gauges, still 20 psi. If I ground the wire to the sending unit, the gauge goes past 50 lbs.
As a final test, I used a 6 volt power supply to power the gauge, put an air hose coupling on the sending unit, ran a wire from the gauge to the sending unit and another to ground the sending unit (positive ground) Using the regulator on my air supply I put 25 psi to the sending unit. The gauge went right to midscale 25 psi. Both gauges and sending units did this. I could raise and lower the air psi and the gauges would go up or down.
I also moved the sending unit to the same port as the mechanical gauge, no change.
Not sure what the next step is. The oil pressure gauge and the fuel level gauge share the same power wire and the fuel gauge is working fine..............
