temperature?

today went for mot and went straight through! great but on the way home the temp went into red ! pulled over waited couple of mins then restarted temp went to normal and stayed there for the rest of journey home ! what was this not engine headgasket first signs i hope!

could be but not always, i have a 2.5 diesel and had a overheating problem immediately after buying it ended up having head done £1200! But i had the problem every now and then afterwards i sh** myself, but i replaced the expansion cap and neverhad it since, as you will see looking around the forum there are loads of reasons for overheating but it is not always serious!!

checked water before going out was low added about 1 litre since then taken out for 1 hour and stayed at half following further investigation think there is leak on radiator how much are these to change.....