It's normal for the level in the expansion tank to go up when the engine is hot. That's just normal expansion. As for your other issue, I would try replacing the thermostat. Hope this helps 🤞
Hi Forncett,
I'm pretty sure I didn't need any locking tools when I did mine. However it was a few years ago. I did have to by a tool to hold the crank pully while I un-did and did up the crank bolt. Must be some YouTube videos on the subject.
Linx
Most kits come with the pullies and water pump. EG https://navigates.gates.com/emea/v/subaru/impreza/powergrip™-kit-%2B-waterpump-%2B-thermostat/gates/kp2th15612xs-3.html
I have a V40 too 😂. D4 engine. It needed a new EGR vvalve soon after I bought it but luckily done under warranty. Been good since 🤞. Looks like a new bottom support is about £55 from Import Car Spares.