engine temperature scale

[volvopilot]

hi all,

I have a 2006 S40 1.8L petrol. I was wondering if anyone knows the temperature scaling on the dashboard for the engine temperature (right gauges). Mine seems to be ever slightly on the cool side. Most of the time around half a dot cooler than the middle position. Just very very slightly.

I know some cars however will always point in the middle in 'operating range'. So it will indicate the middle whenever it is between 70 and 110 degrees for example. In that case it might indicate a problem whenever it is slightly offset.

I was wondering of anyone knows the temperature scaling on V50/C30/S40s.

[LizardOfBodom]

I dont know the exact corellation between actual coolant temperature and "middle of the scale", but mine always stay dead-set at the middle. IIRC, when Vida reports coolant 89 deg or 99 deg it still stays at the middle so I think the variations is very small, unless you are FAR from default range....
someone correct me if Im wrong.

[cheshired5]

It would be preferable to use diagnostics to ascertain the actual coolant temperature.
Cheap options like an ELM327 would be sufficient.

[volvopilot]

thanks. I ordered a cheap OBD scanner and I will do a proper readout.

dead center should indeed be a temperature range as you described LizardofBodom. So that is why I was surprised that the needle is ever so slightly on the cooler side. Might even be a gauge calibration problem.

I will check it with an OBD scanner just to make sure and I'll let you guys know the operating temperature. it should be around 90 degrees correct?

[SwissXC90]

Make sure you are not observing a parallax error

I had the same thought in my head with my car and realised it was simply a parallax error. The gauge was sport on.

[volvopilot]

thanks! It is on the lower side normally because I have seen in it in the middle from time to time. But most often it's just slightly low.

[volvopilot]

received my scanner and I checked out the temperature readings.

the needle is in the middle whenever the ETC (coolant temp) is above 70 degrees C and seems to stay in the middle whenever it is higher.

70 degrees was reached after +- 10 minutes of idling

Mine stayed at around 73 degrees ETC. This seems to be on the low side. This should be 90?

[FracturedButWhole]

Hi,
Temperature should be above 90 degrees, surely. Looks like a possible problem with thermostat and it is a known issue in these engines. The thermostat module itself is held in casing by two plastic clips. With time and temperature, these clips becoming brittle and prone to fracture, leaving thermostat in fully open position and plastic bits in coolant ducts.
There are some videos about thermostat replacement through headlamp keyhole surgery in Fords. Thermostat placement is exactly the same, so hopefully same treatment applies.

Hope this helps.

[volvopilot]

Could it be the coolant sensor being faulty or would that throw a code?

And just to make sure, it will be a complete replacement of the thermostat housing + thermostat

[FracturedButWhole]

Hi again,

I'm yet to experience the trouble with thermostat myself, so sorry for lack of first hand info. However, I did some research on it while troubleshooting other problems and symptoms you described are exactly what you get when the part fails. Check video below, it's for a Ford, but you have the same housing:

https://youtu.be/vooZyEI2Il4

I recommend comments section also, some helpful advice there.

Again, sorry for not being more helpful.