Coolant temp gauge not rising, first drive for three months

Technical Area Engine, Transmission, Exhaust etc
1
  1. My model of MX-5 is: NA
  2. I’m based near: Cambridgeshire
  3. I’m looking for technical help or recommendations on: Coolant temp gauge not rising

Hi all,
I have a 1995 1.8 which has been sitting since March due to a suspension MOT issue. It was driven to work today (30 mins total with 10 mins motorway) for the first time since then, and I noticed that the coolant temp gauge hadn’t risen at all and was reading cold. I checked under the bonnet and the coolant level in the tank hasn’t dropped, the back of the radiator felt hot, the cabin fan would blow hot air when set to do so. This makes me think that there’s no obvious evidence of the coolant not working as it should. That said, the fact the temp gauge doesn’t rise makes me think only two things are possible:

  • The temp sensor or gauge isn’t working / disconnected
  • The heat isn’t reaching the sensor, and is all going somewhere else.

The latter option being too worrying to drive home without figuring out what is the cause!

Does anyone know if this is symptomatic of a common issue? Can the temp gauge needle get stuck in place after sitting for a while?

Thanks in advance for any advice!
James A

EDIT:
Thanks to those who gave me some advice! I changed the thermostat and rear coolant temp sensor but the needle still read cold. I removed the gauge cluster to have a look at the connections, and in roughly pulling the clips out, the needle bounced up to its correct position. I assume it got stuck on low when it was unused for a while, and either the jolts from pulling the gauge cluster out, or the detatching and reattaching of the gauge cluster electrical connections, freed it

2

Hi, the temp sensor for the gauge on the dashboard is located on the coolent housing at the back of the engine. You can access it from the intake side of the engine. It’s below the cam sensor. It has a spade connector that can loosen over time. I recently replaced mine as the spade had split where it joins the sensor. For a genuine one Sensor, Water Temperature Gauge, Genuine Mazda, MX5 Mk1 – MX5 Parts or aftermarket https://www.mx5heaven.co.uk/product/mazda-mx5-mk1-sensor-temperature/

2 Likes
3

Sounds like giving that spade connector a good wiggling and maybe a tighten has to be a good place to start

1 Like