Alfa 159 2.4D Water Temperature - Thermostat Problem?

[bm282]

Folks,
just enquiring as to whether I have a faulty thermostat - staying open? I notice that the temperature gauge mostly reads about a quarter way up (nominally 70) when normally driving. Very rarely does it get to the half way position (nominally 90). I live in the Blue mountains and its particularly noticeable in winter, but even in summer it mostly does the same. Changing the thermostat is both expensive and fiddly on the 2.4, so I would rather be sure before spending money unnecessarily. Does anyone have advice/ thoughts/ their own car's performance. My car has done 143k.
Thanks.

[bazzbazz]

It's either the thermostat/temp sensor or a dodgy gauge. Have to be honest, never know of a water temp gauge on a 159 to fail. Only way to know which it is is via diagnostics checking the information being sent to the Engine ECU.

Replacing the Thermostat in the 159 2.4 JTDm is no harder than in say a 156 or 147 with the exception of having to remove the inter-cooler to manifold pipe & battery & tray.

[bm282]

It's either the thermostat/temp sensor or a dodgy gauge. Have to be honest, never know of a water temp gauge on a 159 to fail. Only way to know which it is is via diagnostics checking the information being sent to the Engine ECU.

Replacing the Thermostat in the 159 2.4 JTDm is no harder than in say a 156 or 147 with the exception of having to remove the inter-cooler to manifold pipe & battery & tray.

So Bazz, its not normal for it to register as that cool? It should sit at the 90 consistently?

So you would say (if not the gauge), replace the thermostat?

I can read the ECU data to rule out the gauge, but as you say, they don't tend to fail. Agree, its not that hard to do - just don't want to if it is ok. I think the replacement thermostat pipework etc, includes a new sensor anyway. Just need to get the o-ring for the manifold pipe to throttle body as well, as these seem to get oversize on removal and are pesky to reinstall.

Let me know.