Water temperature dropping driving downhill

Clark10

Full Member
Apr 13, 2005
205
0
Belfast
I currently drive a TFSI Sport and over the past month my water temperature has been dropping whilst driving downhill. The car gets up to temperature quickly and sits around 92 degrees, but when driving downhill this drops to around 80. I've changed the thermostat and the Coolant Temperature Sender, but neither have fixed the problem. Anyone have any ideas?
 

olitaylor07

Badger Badger
Jul 15, 2012
2,422
1
West Yorkshire
I brought this up over month. It's normal because when it gets up to temp the thermostat opens and lets colder air in which is your not using your engine at such it cools down.

It's the same when you been for a drive get home, then get back in your car 5 minutes later the temp will go back up to warm and then drop with the cold air coming in even though haven't moved!
 

Clark10

Full Member
Apr 13, 2005
205
0
Belfast
I'm pretty sure it didn't do it before, it always stayed on 90, it was doing it through the mild weather we had in December too.
 

Clark10

Full Member
Apr 13, 2005
205
0
Belfast
Just to add, I'm pretty sure the temperature gauge used to sit at bang on 90 and not move, now the temperature settles at around 92.
 

olitaylor07

Badger Badger
Jul 15, 2012
2,422
1
West Yorkshire
Mine didn't either but obviously with the colder air entering the system it will reduces the temps more. Mine sits at 92 aswell. I took it for a service other day and mentioned it and they said it was perfectly normal.
 

Clark10

Full Member
Apr 13, 2005
205
0
Belfast
Just an update on this, I changed the thermostat for a second time and that fixed the problem. Car gets up to temp now and the gauge stays at around 90.
 
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