One of my first questions here was "How do I do a oil pressure light (or a prper gauge). After some time, I have actually done this.
The pressure sender is set to close at 0.25 bar (most pressure sensors of the automotive kind have the pressure limit stamped somewhere on the body). The sensor/sender is a M10x1,5 (metric fine thread) a 27 NPT will work perfectly well. The sender is screwed into the oil filter top, exactly in the center. It will not interfere with the oil filter seal, and being in the dead middle, it will sense the pressure before the filter. With a dirty filter, the pressure may rise and it will be slightly less flow - but that long will no SLK members oil filter go unchanged, I think.
The electric part is very simple. The sender is earthed in a suitable part, in my case the casing for the thermostat. From the sender, earth goes by wire to a red, self flashing LED, located in the dash. The LED ha its positive lead to a piggyback fuseholder together with the Tempomat. A suitable resistor is around 800 Ohm. 640 work as well. The LED awaits a 10 cent LED holder. The (unsymmetric) symbol is a DIY sticky decal until final installation.
To facilitate oil filter change without unduly disturb the connection between oil filter cap and the sensor (Sensor is metal, lid is plastic - so female thread is also plastic. Removing the sensor on a regular basis may be a bad idea), Therefore, the oil filter wrench top has a hole and a handle is welded on top.
The pressure sender is set to close at 0.25 bar (most pressure sensors of the automotive kind have the pressure limit stamped somewhere on the body). The sensor/sender is a M10x1,5 (metric fine thread) a 27 NPT will work perfectly well. The sender is screwed into the oil filter top, exactly in the center. It will not interfere with the oil filter seal, and being in the dead middle, it will sense the pressure before the filter. With a dirty filter, the pressure may rise and it will be slightly less flow - but that long will no SLK members oil filter go unchanged, I think.
The electric part is very simple. The sender is earthed in a suitable part, in my case the casing for the thermostat. From the sender, earth goes by wire to a red, self flashing LED, located in the dash. The LED ha its positive lead to a piggyback fuseholder together with the Tempomat. A suitable resistor is around 800 Ohm. 640 work as well. The LED awaits a 10 cent LED holder. The (unsymmetric) symbol is a DIY sticky decal until final installation.
To facilitate oil filter change without unduly disturb the connection between oil filter cap and the sensor (Sensor is metal, lid is plastic - so female thread is also plastic. Removing the sensor on a regular basis may be a bad idea), Therefore, the oil filter wrench top has a hole and a handle is welded on top.