ords

Manual or auto?

Which engine?

This should have been the first question. Check the glow plugs.

Mine is still on the original Varta AGM battery, so I'd recommend Varta

Are you using a pc or Apple? Apple adds on files which have to be deleted. There is a thread somewhere on this forum explaining this.

Care to share?

As I read it, the OP did not fill it up to the top. The level rose from the minimum level to the top as he was unscrewing the cap.

If you're replacing them yourself, there is no labour cost involved. If you get a garage to do it, then you're going to be hit with a labour charge every time, so it would be cheaper to replace all four at the same time.

It's a TDI

Was it ok before the cambelt change?

Wrong forum

Ask your boss if any mods have been done

This one comes with the sensor, but no cap. https://www.autodoc.co.uk/ridex/14738702#coolant-expansion-tank

If the engine management light is on, it will fail. A warning light only will probably be ok. Call the mot garage and ask them.

Which system in the car do you have?

Ignition on only, no need to have the engine running.

1.6 TDI here. Gets up to 90c on the gauge no matter what the outside temp is. What the actual temp is I've no idea as I don't have OBD11 monitoring it.

Try getting the fault codes read first.

That would seem to rule out anything related to the engine then. Can you post a video or audio file of the noise?

Does it do when coasting with the engine off?

It will probably fail the MOT with the light on.

Plenty of info on Youtube.

Manual or auto?

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