Re: Oil pressure sending unit

Posted by HH56 On 2019/6/12 8:05:28

The sender is at the top right rear of block just behind the intake manifold and next to the distributor. Immediately going to the H side means the wire or sender is grounded.

Disconnect the wire from the sender or don't leave the key on with the gauge pegged or you could burn out the gauge. If the gauge returns to the low end when the wire is disconnected the sender is the issue -- if it does not, look for a short in the wire.

If the sender is a replacement, with the symptoms you have could a Clipper sender have been installed by mistake? The Clipper sender is just a switch designed to work a light. It is normally on but opens when the pressure raises sufficiently and turns off the light. The Packard sender works a gauge and is a resistance unit which changes value. It lowers resistance as the pressure goes higher to make the needle move toward the top end.

You can check your type of sender with an ohmmeter. With the engine off or sender not installed, between the metal case near the threads and the terminal on top a 51-4 sender and 55-6 Clipper sender will read a direct short or maybe a few tenths above 0 ohms. A good 55-6 Packard gauge sender will read much higher starting somewhere around 90-100 ohms and depending on brand could be even higher. If it has shorted it will read low and more toward 0 ohms.

You can get a proper Packard unit from one of our vendors or a Napa OP6091 has been found to work with the gauges.