Thermostat and engine temperature

GeX

GeX

Soldato
Joined
17 Dec 2002
Posts
6,951
Location
Manchester
Hi :)

I have noticed that my car (2002 Xsara VTS) that when holding a steady 70mph on the motorway that the water temperature will drop down to around what looks like 75c. The middle of the gauge is 90c.

The oil temperature sits at a fraction to the cool side of the 'the middle'. The oil gauge is not blessed with numbers so I don't know what it relates to.

Mildly concerned that my thermostat is sticking I looked in to getting a replacement. I have noticed that the temperature listed for the stat is 83c.

Is 83c the temperature it starts opening at, or is it fully open by then? Is it 'the norm' for the water temp to be anything other than the middle of the gauge?
 
clearly.. hence it cooling down - but a cooling system is supposed to maintain the engine at the 'correct' temperature. To me, that is around 90c - but I want to know what others think.
 
83c is at what point the stat starts opening I do believe.

If the system is running properly, the car should get up to 90c and never deviate from that as I'm sure you know.
 
If the system is running properly, the car should get up to 90c and never deviate from that as I'm sure you know.

that is what I thought, but wanted to hear it from a few more people before I buy a new stat
 
new stat time.... every car my GF buys has a dead stat... im trying to convince her its a BAD thing not to have a car thats at operating temperature, but she never even noticed untill i pointed it out on both cars.... :(
 
Hi :)

I have noticed that my car (2002 Xsara VTS) that when holding a steady 70mph on the motorway that the water temperature will drop down to around what looks like 75c. The middle of the gauge is 90c.

The oil temperature sits at a fraction to the cool side of the 'the middle'. The oil gauge is not blessed with numbers so I don't know what it relates to.

Mildly concerned that my thermostat is sticking I looked in to getting a replacement. I have noticed that the temperature listed for the stat is 83c.

Is 83c the temperature it starts opening at, or is it fully open by then? Is it 'the norm' for the water temp to be anything other than the middle of the gauge?

It will move around a bit, the gauge isn't damped like it is on most cars, mine will sit at around that level on the mway, then in traffic get up to just over 90C at which point the fans will run. Yours sounds fine to me.

The radiator is quite big, and if its the alloy Nissens unit is efficient too.

As for oil temperature, normally its on the bottom notch which I am guessing they are 25 degree increments (making it 75 degrees) as its 50 at the bottom and 150 at the top. This will go up to the middle when driven hard on the road.
 
It shouldn't drop down to 75, sounds like the stat is not closing properly which is a very common failure mode. If the thermostat is working the engine temperature shouldn't vary much at all unless you are sat in traffic with no airflow through the radiator.
 
Take the current thermostat out and drop in some hot water. You should see it open if it's working correctly.

Does sound like it's stuck open though.
 
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