Engine Temperature Gauge

  1. My model of MX-5 is: MK3
  2. I’m based near: Manchester
  3. I’m looking for technical help or recommendations on: Engine Temps

My gauge does not get above two or three marks on the gauge, so two marks outside of the Cold.

  1. Is this just a gauge so no need to worry about it?
  2. Will it affect the engine in anyway?
  3. How easy is it to correct?


You need a new thermostat.

You need to sort it. Engines wear faster when cold.


Definitely should go to half way and stay there. Almost certainly thermostat is faulty.

Yup, a permanently rich mixture won’t do your motor or your wallet any good.

Does the cabin heater take an age to get even warm?

The cabin heats up nicely and in good time to be honest.

How much is this issue to resolve please?

It’s a simple enough job.

Drain radiator, remove airbox, remove throttle body, undo hoses, undo thermostat, get fluid everywhere, new thermostat in, replace throttle body and hoses, replace airbox and refill coolant.

It would probably take me between 1 and 2 hours including swearing breaks and tool hunts. A calm mechanic would probably take less time.

Direct from Mazda the thermostats are spendy, get a ford one from Opieoils or similar for £20ish

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Do note there are two different sizes of thermostat for Mk.3s, you’ll need the one with the right length housing. (I stumbled on that when seeking a new stat for Mrs Y’s Mazda 6 which has the same basic engine.)

You can buy the long hose outlet stat and trim the hose by around 30mm, that’s what I fitted to mine. Mine took the shorter version.
Mahle TI 202 82 is the model, available on eBay.
Opie oils used to do them for around £13, appear not available now. As said eBay have them for not much over £20 delivered.
Of course Mx5parts have both sizes to suit whichever model short/long outlets at a premium price.

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In at the garage to get it sorted. Cheers all.

Let us all know how long it took them. I for one would like to know how far out my estimate was!

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It should take an hour max. Outside of that the only fiddly bit really is bleeding it off afterwards as it’s a bit hit and miss and drawn out.

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