Comet88

The new pump only has a dummy connector attached, so the sleeve does not actuate.

I have a 68-plate 1.6TDi Karoq, manual, currently on 43k miles, and owned since Oct 2020 (from 19k miles). It's an ex-Motability car. Since November last year, it has been generating random and intermittent temperature gauge spikes, typically up to 105-110 °C, but occasionally up to 130°C when the engine overheat warning is triggered. As it was just about 5 years old when this first occurred, I had the full belt and water pump replacement kit fitted - so, the water pump was new in January this year. For about 6 weeks, all was fine, then the warnings started up again. Usually, the temp spikes up to around 110, stays there for about 30 secs to a minute, and then rapidly drops back to 90, and is then normal for the rest of the trip (however long that may be). It's been back to the garage (local, trusted, independent) several times, they have had it on the rolling road and taken it for numerous test drives, and cannot get the behaviour to repeat itself. Diagnostics have been downloaded, and there are no faults found. They have also surveyed the engine bay with an IR gun and there are no unexpected hotspots. Last time, the temperature sender unit was changed, but this hasn't altered the behaviour. They think the warnings are spurious (i.e. an electronic fault), but I am not convinced. Now booked in for a cooling system drain, flush and refill plus new thermostat. There was a pattern for a while, in that the first trip of the day usually didn't trigger any temperature increase, but the second or subsequent (starting from a partially warm engine) often did, however, in the past week, I have had three engine overheat warnings on the first trip on different days. Currently approaching "wits end" with steam coming from my ears - any suggestions?