Came back from the shops yesterday after seeing a puddle under the bonnet when leaving the carpark. Got home and the fan was running after I switched off. Checked under the bonnet and the coolant reservoir was empty. The worrying thing is the temp gauge never went past half way even though she overheated.
Having the car trailered to the dealership for repairs tomorrow - hopefully it's just a hose and not too expensive a repair.... This is the first thing that has gone wrong in three years of ownership. Gonna get them to check the temp gauge as well.

 

Bet you a beer it's the ubiquitous leak from the "T" pipe.

 

Remember the temp gauge don't show the real coolant temp! It has a plateau function (I don't know the exact English term, can somone translate, pls.?).

In normal operation (without high load, traffic jams and long idling) the temp isn't that high to leave the plateau in direction to max.
When coolant is missing, the temp sensor on top (empty) coolant lines can't detect temperatures precisely.

By the way: this poor middle class car has no coolant level sensor at the coolant reservoir (at least my model).


catfondler

 

I was thinking that might be the case but I wanted to check. The car definitely did not register an overheating condition even though the coolant was lost - like you say it might have read that way because there was no coolant touching the sensor. But I want to check operation just to be sure.... The last thing I would want is to drive the car in an overheating condition without the temp gauge warning me of that condition...

 

Of course.

If the gauge starts with cold and goes up to middle in normal operation, it's working. At overheating conditions you will also get red warning lights.
(I suppose the coolant temp sensor have to work for this functions.)

If no coolant touches the sensor steam should reach it at least. (In overheating conditions.)


catfondler

 

I think maybe in my case there was not enough steam generated to push the sensor into overheat condition - the coolant leaked out of the water pump before it could heat up enough.....

 

Catfondler. what we call them on this side of the pond is an idiot-gauge. It works just like an idiot-light, only does something when you have a problem. Many Fords have temperature gauges like this that really do not do very much, unlike a real temperature gauge that you can monitor.

 

Nice! (I'll add that to my vocabulary.)

All Volkswagens seem to have it, too. (I don't notice that anymore for a long period of time because I own several OBD devices.)
Unfortunately nearly all drivers I get to know are precisely the target group for thus instruments...

But is there also a more technical term for it?


Cheers, catfondler

 

In my limited electrical experience I once found that Toyota temperature gauges only move up to the mid range and stay there until the engine has almost reached 'disaster' temperatures. This is to pacify customers who worry that their gauges are going up and down at various speed/load conditions. The gauge stays in a 'dead' zone. I can't remember the values, but I removed a Xener diode and a large resister from my gauge on my 4-wheel drive bush basher, and replaced them with 2 other resisters. Thus my gauge showed 'cold' when the engine was first started, rose up until the thermostat opened, and dropped again to the mid-zone, but rose steadily if it detected another rise in temperature, then dropped accordingly when temperature stabilised in the 'normal' zone. This operation gave me more confidence in the gauge and the engine operation. I am sure that other, more electrical competent members could elucidate the process.

 

Do not rely on the instrument cluster gauge to determine engine temperature. Use the Torque app to connect to the vehicle's PCM via the OBD port using a Bluetooth interface.

The Ford Duratec engine uses a head temperature sensor in the Bank1 cylinder head. It operates independent of the cooling system.