Joel's DIY Budget Water Temp Gage by JDwhiteWRX

By stevegolf
( 5 )

6 minute read

Joel's DIY Budget Water Temp Gage

Compliments of JDwhiteWRX @

Hello again!

Got a new DIY project completed today and this one will save me some cash! I've always wanted Defi's but never could bring myself to hand over that much coin. Still the need to monitor temps exists even more so when you start getting into motorsports.

It all started when I stumbled upon this article in Autospeed, these guys write some great articles!

This got me thinking, the only real reason you couldn't use this gauge for all sorts of temp readings is the sensor type, but what if I just placed this sensor inside an appropriate sensor that had been hollowed out  

I was thinking water temp is the most important gauge to get first but I figured if this works for water then there is no reason you couldn't make an oil gauge, air temp gauge etc. So if this one worked out I would buy a few more, they are only $25 each delivered to your door. Just search ?DC 12V Digital Temperature Controller Thermostat C? on ebay.

So a few things are needed to mount the sensor, first thing is a water temp sensor with 1/8npt thread size. I used a commodore water temp sensor from super cheap auto for $12, part number TTS062. I then pulled the guts out of it so I could slide the sensor that came with my gauge inside.

Next you need an adaptor for the top radiator hose, $23 from SCA. This has a 1/8npt fitting so the commodore sensor fits perfect. For Subaru its the 38mm adaptor you need, part No. CAL38WTA

This photo shows the ebay gauge sensor on the left and the commy sensor screwed into the adaptor on the right.

This is the ebay gauge. I decided to put it where the ash tray is but you could also fit two of these in the spare DIN pocket.

To install the adaptor in the top radiator hose you are going to need to drain a bit of fluid out of the radiator. I was able to drain enough without spilling a drop by cracking the plug on the bottom of the radiator a small amount and catching the fluid.

Adaptor installed.

Now to run wires into the car and make the ebay gauge fit in the place of the old ash tray. I ran the wires along the bonnet release cable all the way back to the firewall where there is a grommet just behind the brake fluid reservoir. This brings them out just above the clutch pedal inside the car and you can then easily run them into the centre console.

I removed the part of the trim that holds the ash tray and flip down cover. I used my angle grinder to trim the plastic and the a file to make a snug fit for the gauge. Its actually the perfect size to fit in there and if you are careful it will be held in nice and tight so there is no need for anything to hold it in place.

I took power and earth from my stereo connections and then wired up the gauge. Instructions come with the gauge and are also printed on the top.

This is where I dropped the sensor into the adaptor, I used a bit of left over rubber hose to protect the wire where it drops into the gutted sensor and some high temp silicon to hold it in place.

Turned on the ignition and the gauge sprung to life

Now this gauge also has the ability to control a fan or an alarm or even trigger your waterspray and a temperature of your choice, not bad for $25. The only real downside is it only goes to 110C however it may actually read higher but the accuracy might drop off, I need to test this.

Stay tuned for more uses for this gauge.