mountainpeaking

Basically the title. Had my timing belt / water pump changed on my 1.6tdi Octavia (used OEM parts) done by a mechanic. Everything was fine for a week - drove car maybe 200 miles over 5/6 journeys and no issues. So, I then go on a long road trip... About 3 hours in to a 6 hour motorway journey I see coolant temp rising... This has NEVER happened before. Also, oil temp went up to 110. Coolant go to 115 before I fully noticed and I immediately switched off cruise control, slowed down and within 10 seconds coolant temp was back at 90... Weird... So, I carried on driving... Car felt fine - I switched heater on max into the car to try to dump any extra heat. All was fine for 5 minutes or so. Then, on a big uphill again coolant temp rises... Goes to about 100 before I completely stop accelerating and go down to 45mph or so and it immediately drops back to 90 degrees. I pull over, give the car 10/15 minutes to rest as I'd been driving 3 hours anyways. Hoped it would somehow fix itself. Carry on driving... Same thing happens again on a big hill... Weird. This happens 4/5 times but fans were blowing hot the whole time and the coolant / oil never got concerningly high. But I was having to completely stop accelerating anytime the coolant temp rose, and it immediately would stop rising. Then, randomly after maybe 45 minutes of this, it completely stops. I went up huge hills and oil temp and coolant temp stayed stable. Hooray, I thought. It was gone. It stayed like this for 2 hours or so... But, then again, randomly coolant and oil temps rise again to 100 or so degrees. I again have to let off cruise control. This happens again 4/5 times... But, eventually I made it, without any permanent damage but I am now stuck asking the question - what could this be? Coolant temperature returns back to 90 (from 100 or so) in 5/10 seconds after completely letting off accelerator. I am now 400 miles from the mechanic who fitted the waterpump (who would likely look at it / fix it for free given the circumstances). I'm reluctant to go to a garage as if it is an issue with the waterpump I will have to spend £700-1k on repairs... Does anyone know what I should be doing here? Symptoms seem like a possible airlock to me but hasn't cleared even after cooling overnight and driving again? What should I do? I'm currently street parked in a busy city so can't do a whole lot of DIY work. TLDR; Random overheating 500 miles of driving after water pump replacing. Then stopped for 100 miles. Then restarted. What could it be?

So I have a 2015 (June, Euro 5 Engine) 1.6TDI Skoda Octavia 105bhp (Estate/Combi) I need to replace timing belt / water pump and have a mechanic that can do this. He quoted me £250 for timing belt kit but said I can buy myself if I like. I have found this gates kit which says it fits my car - but, I'm unsure if I need switchable or non-switchable water pump? It says both fit and I'm unsure if that is correct? These are the two - non switchable: https://www.autodoc.co.uk/gates/13671357 switchable: https://www.autodoc.co.uk/gates/16612297 Please could you advise which one to order!

So I have a 1.6TDI Octavia from 2015 (Euro 5) and I'm debating changing the timing belt / water pump. Car currently has 80k miles. Are these engines reliable? Is it worth investing money into this car? What problems can I expect in the next 25-50000 miles? Are there any things certain to go wrong up to 125,000 miles? I will likely sell around 100/125k miles. I'm only doing long journeys (100 miles plus) in the car so no short trips - I'm therefore not super worried about the DPF. Thanks in advance.

After removing component protection lock Smartlink has been deactivated. It states that I need to activate it by visiting a dealer. Im curious how people have got around this - I see online talks of using an MIB toolbox but I don’t have VCDS or OBD11. My software version is: MST2_EU SK ZR P0472T and part number is: 500035874C. I’d appreciate any help with this - I see on ebay people offering to activate it for £20 - is this a feasible solution? Is there a simple guide to do it?