G'day all, I have a 2 door ke30 and I have wanted to fit a tachometer to it just to get an idea on revs I'm doing at certain speeds, I also purchased an oil pressure guage and a water temperature guage to fit as well, now is there any way to use the original oil pressure light sender or the water temp sender, as I quickly just fiddled with the water temp guage under the bonnet the guage quickly went over 100 degrees assuming that you cannot match the original sender with aftermarket guages. Can variable resistors be fitted as a solution or have to fit my aftermarket senders and ditch the originals?

Oil pressure light sender is a simple off/on and won't work with a gauge. You can still use the light in concert with a gauge if you use a brass T piece from the block. Specific gauges will require specific senders and it makes no sense not to use those from the manufacturer

Temperature sensor is a thermister, that changes Resistance based on the temperature.

 

The problem is, for what ever reason, pretty much all manufactures use different thermisters which have a different resistance change per temperature, and often have a different rate of change as well.

 

It is probably possible to correct an oem temperature sender to work with an aftermarket gauge, but you would need an aftermarket temperature sender anyway to measure the resistance in order to calibrate your additional resistors etc. If the non oem temp sensor doesn't fit the oem thread, you can easily get adaptors etc

 

You really need to match the exact temperature sender to the gauge, else its not worth installing it (assuming you are installing it to get higher accuracy temperature readings)

 

As for the oil pressure sender similar story. The standard oil pressure sender is a switch that turns on when the pressure is above a certain pressure. The "idiot light" standard oil pressure light works using this. An oil pressure sender designed for a gauge is a very different widget, it changes resistance based on pressure. Quite a complicated thing to do and they cost a fair few dollars (often the oil pressure sender costs more than the gauge). But remember the sender is what gives the accurate readings.

 

In my opinion unless you have a highly modified engine (different bearing clearances etc) and you are actually worried about the exact oil pressure, the idiot light is all you need as all you want to know is do you have oil pressure or not. My brother installed an oil pressure gauge in his drifo car, wired it all up, fired up the engine, gauge moves to about half, he looks at me and sais "how do i know if the pressure is good enough", i turn around and said "put the damn idiot light back in".