AUDI TT Temperature issue

[coley20]

I recently bought a 2000 audi tt 105k and F-A-SH

On the motorway it sits at about 80C


Today drivig/sat in central london traffic it went slighly over 100C, only seems to do so when its hot outside and sat in the same place for about 5-10 mins

I put the heater on and it went back down to 90C

I have done the 49C trick, the digital display shows a difference of about 15C in different conditions, ranging 76 to 102C

What is wrong, do I need a new stat, or flush the system, a new temp sensor? or anything I cant think of, any input much appreciated

[mpm1987]

Sounds like you may need a new water pump, this should have been done when the cambelt was done, but are sometimes missed. The original comes with plastic propellors, which are known for breaking.

[Tame Technician]

If it was the water pump I would expect it to be hotter than that, and it wouldn't cool down on the motorway, they overheat quite easily when the pumps gone. One way to check (although not a guarantee) is to take the small bleed/return hose off the coolant header tank, rev the engine to 3.5krpm and you should see lots of water come out, if you dont get any, there's no circulation.

I've see brand new 1.8T's running at 100 - 103 ish, thats pretty normal, The cars with the electronic thermostat run even hotter than that sometimes.

Is unusual for it to show more than 90 on the dash gauge, the gauges are electronically damped so between 80/85 and 103/105 it shows 90, so customers dont see it go up and down in traffic.

As long as the cooling fan is working (check this first) and when the fans runs you can feel hot air behind the Rad I wouldn't worry to much. You need to turn the A/C off and run the engine until teh fun cuts in, to check the fan.

If the air behind the fan is cold when the fan comes in, then the coolant isn't circulating and it could be the thermostat or the water pump.

[VAG1]

[quote=Tame Technician]
Is unusual for it to show more than 90 on the dash gauge, the gauges are electronically damped so between 80/85 and 103/105 it shows 90, so customers dont see it go up and down in traffic.
quote]

Lol I knew the car couldn't run at a constant 90 all the time.

[Gren]

Never knew that either.....which is when when my fan needed replacing a couple of months back it used to sit at '90' for a while then rocket up all of a sudden. Must have broken the buffer.

Had similar issues to the OP though. Normal driving was fine but after 2-3 mins stood still the guage would go up (confirmed by climate control trick). Apparently there are a couple of fans that kick in at different temps and one of mine had gone. The second fan luckily used to keep it pinned below 110.