Author Topic: Thermostat  (Read 329 times)

Offline Brad_ED30

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Thermostat
« on: February 14, 2019, 06:52:38 AM »
Hello everyone,

Question around coolant temps...

Ed30
The dial on the dash shows near enough 90 pretty quickly, but the digital menu shows 70 when driving and only 90 when in traffic.

Firstly; does this affect performance?

Secondly; am I right in thinking the main thermostat needs replacing?

Cheers

Offline OllieAKS

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Re: Thermostat
« Reply #1 on: February 14, 2019, 09:07:53 AM »
Hi Brad,

When you say the digital menu, are you referring to a PolarFIS? Because on a MK5 they do not show the coolant temp on the normal cluster.

If it is running cold it won't affect performance too much, but it will run lean and cause slightly higher fuel consumption. Best of replacing the main thermostat if you have any doubt and if it hasn't been done before  :smiley:

Offline Brad_ED30

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Re: Thermostat
« Reply #2 on: February 14, 2019, 10:30:35 AM »
Hi Brad,

When you say the digital menu, are you referring to a PolarFIS? Because on a MK5 they do not show the coolant temp on the normal cluster.

If it is running cold it won't affect performance too much, but it will run lean and cause slightly higher fuel consumption. Best of replacing the main thermostat if you have any doubt and if it hasn't been done before  :smiley:

I’ve accessed the coolant temps through the digital climate control cluster by holding the air on and vent up buttons at the same time. I’ve used he setting 19,02 to access the coolant temps based on what others have said but this may or may not be correct??

Offline Octoparrot

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Re: Thermostat
« Reply #3 on: February 14, 2019, 11:34:15 AM »
If it gets up to and stays at 90 consistently then I'd say your thermostat is fine.

Offline RedSwede

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Re: Thermostat
« Reply #4 on: February 14, 2019, 04:48:09 PM »
On mine, I noticed it was not getting to temperature on the dial. I checked on the climate, 19.2 or whatever, and it was never above low 70s.

I had it in for a thermostat replacement (at not inconsiderable cost!) and since then the dial sits bang on 90. But the climate always sits in the 83-85 region. This is not right, because when the car is stone cold it reads 5 degrees lower than ambient.

So I bought a new temperature sensor - the one for the ECU/dials is easy to get to - and it was then reading correctly with a cold engine. But after a long drive, it never got above ~75 degrees. Ebay rubbish...

Moral of the story is - don't bother wasting time and effort if the dial is in the middle  :smiley:

Offline gixerben

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Re: Thermostat
« Reply #5 on: February 14, 2019, 06:04:16 PM »
Mine is just in the process of being changed at the moment, slow to heat up and after an age sat at 90 but the on the open road would soon drop to 70 (on the gauge).
Im just changing both main stat and both senders....

Awaiting the car returned and the bill  :thinking:
Pirelli GTI

Offline KJNGTi

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Re: Thermostat
« Reply #6 on: February 15, 2019, 09:09:39 AM »
Out of interest how quickly should it get to 90, mine takes 10-15 mins of A and B road driving. I had the thermostat done before Christmas because it wouldn’t get to 90 and when it did it would often drop as soon as we got moving again. It now sits at 90 but does take time to get there.

Offline bobby_fodge

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Re: Thermostat
« Reply #7 on: February 15, 2019, 09:31:42 AM »
Out of interest how quickly should it get to 90, mine takes 10-15 mins of A and B road driving. I had the thermostat done before Christmas because it wouldn’t get to 90 and when it did it would often drop as soon as we got moving again. It now sits at 90 but does take time to get there.

Mine is about 10 months old after never getting to 90. Now it takes similar to yours to hit 90.

Offline Dan_FR

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Re: Thermostat
« Reply #8 on: February 15, 2019, 10:02:42 AM »
How long it takes varies massively depending on ambient temp, driving style from cold, whether the cabin heater is on etc. Mine can take anywhere from 5 minutes up to 15 minutes, and anywhere from a couple of miles up to about 7 miles

The actual temperature (not the instrument cluster display) should get up to around 88-92 degrees C and stay there, give or take maybe 5 degrees C. If its at 70 degrees C then it needs replacing. The instrument cluster is designed to show 90 anywhere from 75-105 degrees C
TFSI... Revo Stage 2+... . WMI.... VCDS HEX + CAN, MPPS, VAG Commander & VAG tacho - South Wales

Offline KJNGTi

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Re: Thermostat
« Reply #9 on: February 15, 2019, 01:42:26 PM »
Sounds like mine is normal... good news

Offline andyiseddy02

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Re: Thermostat
« Reply #10 on: February 16, 2019, 03:48:39 PM »
I had words with the place that replaced the main one on mine. I found out after doing my own research that the car had two.I asked them why they had not mentioned the car had two and replaced them both when they had it in and drained.
Some cars have three!!!
The car is a Passat but same engine. Temp' up to 90 in under three miles.