Not getting up to temp, driving me nuts!

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Minstadave

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Every winter I have the same problem on my 2.0T (2005) it just won't hold 90 degrees solidly.

Ive had the stat changed last year and it was better but still dropped below 90 when it was cold. It was then fine through the summer. As the temps have dropped this year it wasn't holding 90 degrees again so I changed the sensor for a new beru one hoping it would fix it bit it didn't.

It warms upto 90 by about 15 minutes but then drops to 80 even cruising on the motorway at 70.

I could try replacing the stat again, but that's pretty expensive, or get an oem sensor but I doubt thats the issue now.

Any other ideas? Thank you!
 
Surely that's normal? When you are cruising more cold air gets to the engine? Mines the same don't see the problem ?
 
I'm not sure, lots of people say it shouldn't budge off 90 once warm.
 
I've just been doing some research and I can see that?? Mine in town is always on 90 dead but when in driving it always drops to below that??? I thought it was normal
 
How much was the stat? And what effect does this have on the vehicle?
 
The thermostat is a couple of hundred quid to replace, mostly labour as its in an awful position meaning the alternator has to be removed to get to it.

The stat will send coolant to the radiator once it reaches a certain temp, if it gets stuck open it will allow coolant to the radiator before the engine is fully warm. Lower coolant temps will make the engine run too rich.
 
I've had three 8P's.

170 TDI and 2 S3's.

Once the temp reaches 90, they have always stayed there. obviously not if its switched off...

Something is a miss somewhere mate.
 
Sounds like its nothing to worry about to me, the temp will naturally fluctuate due to the cooler air temps and when you're travelling faster there's more cool air flowing in. The thermostat will open at a set temp for example 98c then close at say 80c, so if you're watching the gauge like a hawk sometimes you may notice it drop as the stat opens and flows water from the cooler rad area, it's just working how any stat should.

As long as your stat opens and closes at the temps it's designed to and not sticking open/closed then you're fine bud.
 
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One other thing to check maybe is the rad / expansion cap is holding a good seal, remove it (when engines cold) and check for any swollen rubber gaskets etc, then with the cap pn and car at working temp listen for any leaking air, if there's any pressure loss that would effect it, under pressure water boils at a higher temp, and even higher again with coolant in it, loss of pressure could effect it.
 
I know I've got a very small leak in my rad very small I need to put a dribble in every 2 months would that cause a fluctuation in temp?
 
Marc. said:
One other thing to check maybe is the rad / expansion cap is holding a good seal, remove it (when engines cold) and check for any swollen rubber gaskets etc, then with the cap pn and car at working temp listen for any leaking air, if there's any pressure loss that would effect it, under pressure water boils at a higher temp, and even higher again with coolant in it, loss of pressure could effect it.
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That's interesting, I've never needed to top up my coolant but will get the garage to look it over when its next in.
 
So much shocking advice in this thread! If you don't know what you're talking about, don't make wild guesses.

The car should hold 90* when up to temperature regardless of conditions, if it isn't getting up to temperature then it is one of two things or both.

The thermostat or the coolant temperature sensor, thermostats have a habit of going every two to three years and temperature sensors tend to last a fair while longer however at 7 years old it's probably due for replacement.

It can only be one of or both of those two tings, and they are the only two means the engine has of maintaining it's temperature.

A good way to check the coolant temperature sensor is to drive the vehicle to get it up to 90* and then leave it ticking over with the bonnet shut and see if the fans engage. If they do then the temperature sensor is regulating the temperature as it should.
 
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JamesO said:
mjr901 said:
would get hot if anything buddy.[/QUOTE

Does it affect performance? It's been like that since I bought it thought it was normal??? ������
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I highly doubt it, but it's something you want to get fixed. the system is supposed to be pressurised. it'll p1ss out one day and everything will get very hot and boom, gasket goes.
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Brodster said:
In your opinion!!! You trying to kick off in the 8P section now??? :applaus:
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No kicking off here, I'm all good in the hood. I just don't like to see people fed bad information :)

VAG cars should not fluctuate in temperature depending on the conditions, when up to temp they should all hold 90*'s regardless. If they don't then something is wrong. Simples :)
 
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mjr901 said:
And indeed that is what I said...
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More aimed at Marc. to be honest, your post is bang on. :icon_thumright:

-

It shouldn't be all that exepensive, £200 isn't a bad price for a garage to do the thermostat again and I believe the temp sensor is easily accessable when doing the thermostat on a TFSI so the two would be easily done at the same time hopefully for only the extra cost of the sensor.

Unless you want to give it a go yourself, in which case the belt needs to be removed along with the alternator then it's a fiddly and time consuming but straight forward job. The belts are directional once fitted and run so if you do it then make sure you chalk an arrow on the outside of the belt to show the direction. It's a good three to four hour job for somebody who is new to it but if you're methodical and do good research online first there isn't that much which can go wrong.

Removing belts isn't as scary as it seems, and VAG have helpfully made the tensioner incredibly easy to release and re-tension.

Before you go mad with it though get it fault scanned, and refer to this with any codes you do get. I'd suspect this one - 18613/P2181/008577 - Ross-Tech Wiki
 
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I think you're not getting what I was trying to explain to the op 16klappe, obviously if he's running miles off on the temps, or the car is running cool constantly there's an issue.
I was trying to point out that there will be variations in temp - the stat is designed to open and close at different temps (apologies for not knowing the exact temps of his exact stat) so any movement within that range is 'normal' and this is maybe what the op was noticing being as the temps he mentioned were so close to normal running temps.
I get that vag run at 90, at least on the gauge, but no car will stay exactly at 90c, the stat would have to open at 91c and close at 89c to do that, and that simply isn't a workable range.

But as you say, shocking advice! So ignore me lol. I only used to build and fit cooling systems for race cars and bikes for many years. :)
 
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My understanding is that the temp gauge will read as 90 over a range of temps, so it's pretty abnormal to not sit at 90.
 
Marc. said:
But as you say, shocking advice! So ignore me lol. I only used to build and fit cooling systems for race cars and bikes for many years. :)
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Having knowledge of how bespoke cooling systems on race engines work is no prerequisite to being knowledgeable on OE VAG cooling systems. You don't need to school me on what a manageable thermostat range is, we studied that in the first of three years of NVQ level MVT and again in the first term of my degree in motorsport development.

Sounds like its nothing to worry about to me, the temp will naturally fluctuate due to the cooler air temps and when you're travelling faster there's more cool air flowing in.

[snip]

As long as your stat opens and closes at the temps it's designed to and not sticking open/closed then you're fine bud.
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As Minstadave says the gauge is dull in a sense that it reads 90* within the thermostats operating window so as not to cause erratic readings. For reference the standard opening for VAG petrol engines is 87*, so his thermostat is not within tolerance.

At this point I'll bow out and go back to the 8L creche for fear of rustling feathers and being labeled a trouble maker; good luck JameO I hope you get it sorted one way or another.
 
Right, all booked in to have it sorted, thermostat, has to be less than 30 quid I reckon and labour cost will be 50 quid so not too bad I don't think?
 
Sounds too cheap! Who quoted you that? It's a big job, some places insist on taking the inlet manifold off at around 4hrs labour, others just take the alternator off and charge 2 to 3 hours.
 
make sure you use the oem stat and cts
£200 is way to much fitted for stat
iv never had an audi that didnt sit at 90 even in -5 motorway or not
only time it drops below 90 or above iv had a problem stat or cts
 
Minstadave said:
Sounds too cheap! Who quoted you that? It's a big job, some places insist on taking the inlet manifold off at around 4hrs labour, others just take the alternator off and charge 2 to 3 hours.
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and thats the places you dont want to go to
 
JamesO said:
Right, all booked in to have it sorted, thermostat, has to be less than 30 quid I reckon and labour cost will be 50 quid so not too bad I don't think?
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It's my mate so that's why 2 hours labour at 25 quid an hour which I think is cheap and it will be alternator off, that's ok though?
 
all my vag cars have gone to 90 and stuck there... even when it was -18 a couple of years back

i'd put bets on it being a lazy stat thats not closing fully, as for time to warm up mines up to 90 on my 7min/5mile drive to work
 
Ste_Nova said:
all my vag cars have gone to 90 and stuck there... even when it was -18 a couple of years back

i'd put bets on it being a lazy stat thats not closing fully, as for time to warm up mines up to 90 on my 7min/5mile drive to work
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Fingers crossed ill report back after the new stats been fitted
 
Right the car is in with my mate tomorrow, got his van for the day :-/!!

I am just a little worried about the long term damage I might have caused by driving like this for the last 12 months nearly??
 
JamesO said:
Right the car is in with my mate tomorrow, got his van for the day :-/!!

I am just a little worried about the long term damage I might have caused by driving like this for the last 12 months nearly??
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No damage
 
Get your mate to plug it into an OBD scanner and check there isn't a fault for the temp sensor, it'll be a costly exercise if it turns out it's the sensor not the stat.

:)
 
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JamesO said:
Right the car is in with my mate tomorrow, got his van for the day :-/!!

I am just a little worried about the long term damage I might have caused by driving like this for the last 12 months nearly??
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Relax buddy, you have no reason to worry unless you've overheated it a quite a few times. Car will have told you if it was mega got anyway.

sleep easy.
 
mjr901 said:
Relax buddy, you have no reason to worry unless you've overheated it a quite a few times. Car will have told you if it was mega got anyway.

sleep easy.
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It's never over heated always run cold
 
Artimus said:
had the anti-freeze \ water ratio checked?
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It won't make any difference at all, run on 100% water or a 50/50 G12 or G13 coolant split it should still hold 90.

Track cars should always drop their coolant and run water for safety reasons, I've switched between running a G12 mix and 100% water and it makes no difference.

There is nothing else for him to check, if it's running cold when up to operating temperatures it can only be the sender or the thermostat.
 
My mate ordered the part which was 9 quid seems a bit cheap anyone got a part number so I can check? Thanks
 
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