Dual Purpose Gauge.

[Guest mcramsay]

I think part of my high temps is due to my oil cooler being much smaller in size than the standard m3. Also with it being an eBay special I doubt it's doing much at all. I am interested to see what my oil temps are when out an about but I don't want to add an additional gauge or swap one of the others out for a oil temp gauge. As a cheapo fix I was thinking about the possibility of using the current installed water temp gauge to function as both a water and oil temp my idea was to install another water temp sender in the oil system and then wire onto the same gauge via a small inline push button on the dash.

 

So water temp will show normally and then when I push the button and hold it would switch to reading from the sender in the oil gallery... release and back to water again

 

Any thoughts on why it wouldn't work?

[cb750]

Oil temperature gauges usually have a higher maximum reading than water ones (150 instead of 120). If your oil runs hotter than 120 then you could damage your water gauge

[Guest mcramsay]

I would be worried if I was seeing oil temps greater than 120!!

[IanS]

only the sender would be affected by the higher temps, nothing else could be affected.

[cb750]

I have had instances as an ex instrument engineer of having gauges go out of calibration when they are subject to inputs greater than their scale maximum but it does depend on their construction

[Big Jim]

Engine oil will normally run at a very similar temp to the water temp, if you do a bit of thrashing the car, your water temp will rise slightly above it's normal running temp and the oil temp will follow it but lags behind, once you start to drive normally again, your water temp should drop back to it's normal running temp after about 10 - 15 mins, but the oil temp will again lag behind and take longer to return to normal.

You can get an electronic oil temp gauge, then with the sender fitted to a sump plug made to take it, you get correct reading of the oil temp being pumped from the sump.

 

(not sure if this is the correct one for you but you see what I'm talking about) http://www.ebay.co.uk/itm/Mini-Sump-Plug-Adapter-4-Smiths-Oil-Temp-Sender-Capilliary-Race-Rally-/152471835279?hash=item238007928f:g:DJcAAOSwYGFUx56O

Or one of these; http://www.ebay.co.uk/itm/Sump-Plug-Sensor-Adaptor-Oil-Temperature-Temp-Gauge-Sender-Defi-Prosport-M14-/271998661648?hash=item3f54623410:g:OQkAAOSwVL1WB8rg

http://www.ebay.co.uk/itm/Sump-Plug-Sensor-Adaptor-Oil-Temperature-Temp-Gauge-Sender-Defi-Prosport-M14-/271998661648?hash=item3f54623410:g:OQkAAOSwVL1WB8rg

Edited May 3, 2017 by Big Jim

[Dave R]

It's possible... As long as your gauge isn't an old fashioned hot wire type and moves fast enough... If that's the case a push button may not be practical