I'm looking for a gauge of some sort to read my coolant temperature. In another thread of mine someone mentioned using an ultra gauge. Are there any other options, preferably cheaper? I'd like to see what the maximum temp my engine gets to before the thermostat opens.

In addition, how would one wire this up?

ScanGuage 2 or UltraGuage MX1.3 are both good options. I have the Ultraguage. I like that it can display 4,6,or 8 items per screen. Here's an article for comparison. Scangauge II vs. Ultra-Gauge: First impressions If your vehicle is 99 (might be 98?) or newer and automatic either one can display transmission fluid temps as well.

Ultra gauge probably is the easiest/cheapest option. It just plugs into the OBDII port

Short term or long term?

For short term just get a cheap infrared thermometer, and measure the temp of hose before it enters the radiator. At that spot the temp should be the highest, and that's a good/cheap way of spot checking your temps.

For long term I like UltraGauge, and have one on every vehicle I own. Another option is to install a temp gauge, and put your sending unit pre-radiator.

Mike

Cheap? I put this one in my 98 before I built my own and it worked great. Nice part is that you can have it sound an alarm if temps hit a certain target. Same w speed. Tire adjustment for speed. Can read and clear codes too. It sits on a little sticky pad in good visible spot. Cable routes right behind it to OBD. I got it on AMZN prime for $25, but for some reason not available there now, but it's on eBay for $27. The cool kids have the scan gauge and ultra gauge, but this is functional. Other screens show all the fuel trims and other OBD protocols. Can't be modified to extract trans temp like others seem to have figured out on UG. Trans is not part of the OBD protocol, but I think 99+ it's in the ECU and guys used some voodoo to display it.

Leaningtech P10

Cheapest option would be to get a Bluetooth OBD2 scanner and use an app on your phone to view the temperature. The bluetooth scanners are pretty cheap - usually only $10 to $20. Just make sure you get one that is compatible with the app you want to use (Torque, Car Scanner, OBD Fusion, etc)

I don't know that you'll be able to see a definite temperature change when the t-stat opens though. If you have the standard 180 degree thermostat, you'll only see a gradual temperature rise to that point, and then hold between 180 and 190 during normal driving conditions.

haven't tried an ultragauge but probably should. My last project car(69 vw with a 96 subaru motor) had no way of making dash reading work so i went through 2 different ways of measuring temp.

the first was a barebones thermometer/clock/volt meter. i say barebones, it was literally a bundle of wires with a tiny digital read out. no options, it blinked through all three every minute and i hated it. there was not only a lag on the temp reading, but if you were overheating while on the other readings you wouldnt know about it for like 30 seconds.
it had a little temp rod that i tapped a hole for right before the thermo but it was still just lame and clunky.

the second was this guy:
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
using OBD fusion

and it changed the game for me. i was finally able to have a cluster(albeit on my phone) with readings for anything the 96 OBDII ECU measured for.
this was the initial setup, helped me tune for idle and realize my alternator was almost donezo.


Anywho, it was easy to use, worked well and 30 bucks. That being said i will probably buy an ultragauge next time

I don't think any of these gauges are going to tell you when your thermostat opens.

To measure coolant temps, the absolutely cheapest is a $10 bluetooth, they're all over amazon. I have one on the jeep and it works fine for diagnostics, etc.

For on the road monitoring, the Ultragauge is great. It's plug and play. The only work you have to do is select which gauges you want displayed and how you want the alarms to function. Plus maybe a little data entry if you want to see trans temps.

Bluetooth OBDII dongle and the Torque Pro app.
I bought a bluetooth dongle on Amazon for $11 and it works perfectly.

You can customize the Torque Pro app with alarms, emission readiness monitors, check engine light checks, temp sensors, horsepower, MPGs, etc. The sky is the limit, pretty much.

another vote for the torque pro app. very affordable. I had an old phone that before took it off line installed the torque pro app, so now I have a phone that just does that, in a dash holder or can just throw it on my pass seat.
have the torque pro app on my mew phone also, and its easy to move the dongle from one vehicle to another
ive never tried the torque pro for reading or clearing codes, don't know if it can, but I have a tool for that ,, that I got long before torque pro came out.

had a scan gauge, still do in my sons taco, hard to read while driving ( for me) never tried the ultra gauge.