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VW Running hotter

Hello group…
Back in the summer on a 30° day, my heater hose blew.
I replaced the hose and topped it up with antifreeze.
Now however, my engine temperature runs hotter. Used to run consistently at the half way mark, but now intermittently at the 3/4 mark on the gauge.
I say intermittently because sometimes it runs right where it should, about halfway on the gauge, sometimes as high as the 3/4 mark, even though the outside temperature is colder… -4 today and it was running almost right on the 3/4 mark and holding.
Any ideas?
All I can think of is, the thermostat is failing intermittently, or the water pump is failing… But how to tell if the pump is bad?
Both cooling fans work and when the car is idling, I noticed they do turn on and off.
When I had it in for a tune up, I asked the machanic to check the coolant, and he said it was fine, good to 40 below.
Thanks in advance.

What year? A bad thermostat could do that, as could air trapped in the system. Any loss of coolant?

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So where do you live?

The North Pole?

Tester

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It is a 2001.
I wondered about trapped air too, but don’t know how to eliminate any air
if there is.
I haven’t noticed any loss of coolant. The overflow ball tank, has a hi and
low mark and the coolant level is right where it should be and doesn’t
change.
Thanks for your response.

And no, it quite at the pole…
Harriston Ontario : )

30 Celsius = 86 Fahrenheit

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Check the coolant level in the radiator, not just in the overflow tank. Beyond that, there’s air in the cooling system, the cooling system isn’t holding pressure, thermostat is faulty, or there’s a head gasket leak from the cylinders into the cooling system. I had a similar problem this past summer where my Corolla wasn’t holding the coolant temp steady like it should. Didn’t happen in around town driving, but if I drove a long way on the freeway, when I finally got off the freeway then it happened. Turned out there was a minor leak where a hose connected to the water pump, which allowed the cooling system to partially depressurize.

These setups on the vw is different than what I’m used too. No rad caps,
really small ball style over flow tank, which I might add, seems to be
holding pressure, as it spits off when I loosen it, when hot.
When I replaced the heater-thermostat hose, before I connected it to the
firewall, I poured coolant down the hose until coolant came out the nipple
on the firewall. So I just assumed the system was full, no air. But don’t
know that this is the proper way on these systems.
Not sure how to bleed the system. I couldn’t find any drains anywhere.

A Haynes or Chilton’s manual would tell you. Or just stopping by a VW dealership shop when they aren’t busy, somebody there would likely be happy to explain it or give you a print out. No need to re-invent the wheel, diy’ers would serve themselves better by securing some version of the car’s repair and maintenance documentation.