Hot weather locally last week, Thursday and Friday both 39°C. Drove my 98 C2 to work both days, 80km round trip with a fair bit of stop start traffic. Temp gauge was showing around 100°C, Torque app to the OBDII said more like 108 to 110.

Anyway got a slow blink indicator on the temp gauge halfway home. With the engine off could hear bubbling in the engine compartment . Waited for the engine to cool a couple of hours and cracked the coolant cap.

Topped up (only had water) and it took over a litre to get back in the range. Restarted but still the blink. Left overnight, checked level in the morning, no further loss . Restarted, Still blinking.

Checked the engine compartment temperature sensor, seemed to be in the correct position. Also pulled the sensor connector and jumpered the contacts, as expected the engine compartment blower came on.

Had a few short runs over the weekend and temperature seemed fine, car ran well but indicator still blinking. Torque app can't see any faults .

Any ideas ?

p.s. I should add this car has had its engine stripped and reassembled 1000km ago, and an oil change last Wednesday.

 

One liter is quite a bit to add, so you probably have air in the system. You need to "burp" the coolant system. Manually raise the burp valve on the coolant tank and leave it up for a couple of heating/cooling cycles. What led to the low coolant level? When was the last time you checked the coolant level?
See Post #6 in this thread about the blinking light https://rennlist.com/forums/996-foru...when-cold.html

 

Thanks, I'll try that. Coolant would have been completely refilled at the shop when they put the engine back in, I'd imagine, 1000km ago (3 weeks), I didn't have any lights blinking before Friday so haven't checked the level recently at all.

I've read all the threads I could find (reason for this thread's name), hence the check of the blower (to rule out item #2 on the list in your linked thread) as well as the top-up (to address item #1). Nobody seems to have had quite the persistent problem though.

I assume there is another sensor other than the one in the reservoir, as that one is definitely "under water" and shouldn't be the cause of the low level reading.

 

 

I would be mostly concerned with where the liter of coolant went. I would pressure test the system and verify system tightness. If the system was properly filled using a vacuum fill tool, it should not have needed to be "burped".

As far as the warning light, it could be that the sensor in the coolant tank has stuck (possible some muck in the bottom). it is just a float with a magnet on it that drops when water level drops and closes a magnetic switch on the bottom on the reservoir. You can disconnect the plug and the light should stop blinking if the float is stuck, then jump the wires and it should start blinking.(note: you have to cycle the key to stop the blinking also.)

Do not play around with the car and a cooling system issue , you can't trust the temp gauge when there are problems, the temp sensor ONLY works with hot liquid, it does not work with hot air, and hot air does not circulate as required.

 

I used an airlift when doing my coolant change and i still had air in the system for about 6 more heat cycles. I think its possible u just pushed an air pocket through. No clue why the light didnt go off after the fill up, maybe the temp sensor is tripped for high temp because there is still air in the system?

 

When using a vacuum fill tool, the system is put under 23 in/hg and has virtually no air in the system. For air to enter the system it would have to have an air leak, or be introduced with the coolant. When properly using the vacuum fill tool, I have to remove coolant from the expansion tank after fill due to overfilling (literally full to the cap) ,so that expansion room is available.