Engine overheating Suspected thermostat?

R555MAC

New Member
Hi, I am new to the forum. I end up here a lot reading through posts so nice to actually sign up! I am really hoping for some help. I have been searching the Internet to try and get some clarity regarding my problem. I have searched the forum for my latest problem but not found the exact symptoms/detail i was looking for. Information and walk through on the T6 seem much harder to come by than older models! So here it goes.

I have a 2.0tdi 4 motion which has began to overheat. Only under load. I live in the French alps so I am constantly going up hills. Although the engine will heat up fast the coolant returns to normal temps fairly quickly aswell as soon as revs drop/Road eases off. Oil temps stay fairly high though. Temps as you would expect go up very fast on steeper high rev low speed driving. On mellow uphills at 40+mph the airflow helps a lot. I am typically having to run the heating as soon as I see the coolant come up to temp.

The reason I am asking here is my local garage are not certain what is going on. So I am booked in with VW. Once I drive to VW (down a mountain) I won't be getting the van back until the problem is resolved as I would warp the head for sure!

I believe it is the thermostat but they are unwilling to swap it out until VW diagnose the issue. They think it could be the head or head gasket. I have chemical tested the coolant reservoir for Co2 and no issue. No smoke, no fluid loss, no fluids mixing. The van can idle indefinitely and no overheating. I just don't think it can be the head. But I am certainly no expert!
I have been making short journeys (just gets up to temp as i arrove at work) for over a month now due to work commitments and the crazy wait time for VW.

They (local garage) think it could be the head as the water pump and timing was changed in 2019 by VW. And as the coolant temps drop fairly quickly they think the cooling system is working as it should (which it clearly isn't...) so they believe thermostat is okay. And the fan kicks in when it should. Also I had to have my CT (MOT) and they couldn't perform the emissions test as with no air flow on the rolling road the engine started to rapidly overheat. I had pre warned them so they stopped the test. Maybe this is also helpful info.

So my main questions are;

Does anyone here with experience still think it's likely to be the head?

Is it possible/likely the thermostat is not fully opening (this is what I think but have limited knowledge)

Chances of water pump not working at 100%? No fluid loss though. But I'm not sure what to look for and it's not an old part.

Any other ideas?

Finally. On this model thermostat replacement looks like a fiddly job but possible. Should I attempt this myself without specialist tools for preventing a vacuum when replacing the coolant? I am considering trying it later this week, but wouldn't take it on if I risk creating a bigger problem.

I asked the local garage to replace it (thermostat) as its the cheapest thing to do, likely to be the problem and rules it out at least. But as I said they refused. Also being in France for this entire month the other 2 garages I can reach without the van overheating have all been closed for 4/5 weeks...hence this has all dragged on to this point. In part I was hoping to avoid VW here as the customer service is not great and prices are crazy in France.

Sorry for the long post, wanted to try and cover in detail. Hoping someone can help. At worst it finally goes to VW on sept 5th. Unfortunately I have had issues with VW previously in France so not excited about that experience again.

Again any help/advice hugely appreciated!
Thanks
 
Have a look at this
 
I will mention thus to VW on Monday. I haven't had a look to see what type of pump I have.

Hoping for thermostat. Worst case water pump. Either way quite big jobs on the T6, ah well. Just got to think the worst when i get the bill and hopefully be pleasantly surprised...
 
As far as I’m aware there is no requirement to replace a shrouded pump with the same type.
There are non shrouded pumps available.
There are also pumps with alum‘ alloy impellers instead of plastic.
 
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