The temperature light in the DS works

The only warning light in the Citroen DS I wasn’t sure worked was the temperature warning.  You can test the bulb by pressing the button, but that doesn’t testing the sender and the connection.   Today, I found it does work, and that my temperature gauge is pretty accurate; The DS overheated today and I was greeted with the little temperature light and the STOP! light too.

I was driving along Wakehurst Parkway from Mona Vale to Frenches Forest, and the temperature was sitting at the top part of the ‘white’ section of the temperature gauge.   However, on going up the final hill, it went into the red and the warning light and STOP! light went on.   Pulling over into the next side street, I waited for it to cool so I could add a bit more water and get the car home.  Only 28c today, so not overheating weather to say the last.

Given the overheating happened on the open road, cruising at 80km/h, my theory is that the radiator is partly blocked.   I may still need a new radiator, or at least a recore, but I figured it was worth trying a good flush of the current system.   I had heard of using diluted vinegar, so I figured it was worth a shot.   There is a bit of a downside, as disturbing the scale and deposits in the system can cause leaks etc, but at this point something needs to be done.

The system was pretty filthy.  The previous owner had been using rainwater as coolant, so there were plenty of deposits as can be seen below.    I have also ordered a new thermostat while I am at it.   Hopefully this fixes the problem and I won’t need a new radiator!