# normal operating temperature range?



## thewolf (Jun 20, 2010)

Hi,

I have a 2001 Audi TT 1.8T 180HP (AUQ engine).

After the car has warmed up, my temperature gauge reads 90C most of the time while driving.
When the actual temperature is between 80C and 100C on channel 49 on the climatronic, the gauge stands still on the 90C mark. Does your dashpod have the same "weighting" interval?

Recently, only when stuck in traffic or when stopping after a ride, sometimes the gauge will go over the 90C mark, with channel 49 actually reading over 100C (if I remember correctly up to 105C).

Recently I replaced the dashpod and the timing belt with the water pump, the thermostat valve was replaced about half and an year ago.

I don't remember the gauge going over 90C often in the past (when my previous dashpod still worked fine). Maybe I don't remember correctly and it's normal that the temperature goes over 100C sometimes? Or this looks like a little overheating? What could be causing it?

What is the normal operating temperature range for the 180HP engine?

Thanks.


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## V6RUL (May 28, 2009)

90C is normal, check your fans cut in when hot.
Steve


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## thewolf (Jun 20, 2010)

V6RUL said:


> 90C is normal, check your fans cut in when hot.
> Steve


The fan kicks in around 98C.

What I'm trying to understand is if a little over 100C is still normal, if the car is not moving and the engine is running and if it's normal to see the gauge sometimes go over the 90C mark.

Thanks.


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## horneteer (Oct 21, 2008)

I've also got a (remapped) 180 and the coolant temperature reaches about 102 deg C when stationary. Fans work and temps drop down to between 93 and 96 deg C when on the move. Noticed this tendency after fitting a new thermostat and temperature sender. Coolant temperature reported by liquid tt is in line with what the gauge on the dashpod reports.

I think this could be normal but that owners with older thermostats may not see the higher temperatures because as thermostats wear they have a tendency to open more readily causing relatively low engine temperatures. Not sure though and interested to hear whether this is the norm.

Cheers
Al


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## Hoggy (May 8, 2002)

Hi Al, Your temps look quite normal & as it should be to me.
Hoggy.


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## steve180bhp (Dec 26, 2007)

when warm your temp should sit at and stay at 90c. If it strays from it ,check your thermostate and temp sensor (the green one).The sensore is easy to change ,the thermos a little more tricky but if you know one end of a spanner from the other ,you can do it. To check if they are out ,do the 49c trick viewtopic.php?f=2&t=139803 .


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## horneteer (Oct 21, 2008)

Thanks folks. Steve, your thoughts seem to echo those of a lot of people who suggest that if the temperature gauge strays from 90 once warm, even if sitting in traffic, then you probably have a problem. Others think that it is not a problem if the needle creeps over 90 when stationary, as long as it doesn't hit the red. Perhaps these different observations are just variations of the norm.

Cheers,
Al


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## thewolf (Jun 20, 2010)

horneteer said:


> Steve, your thoughts seem to echo those of a lot of people who suggest that if the temperature gauge strays from 90 once warm, even if sitting in traffic, then you probably have a problem. Others think that it is not a problem if the needle creeps over 90 when stationary, as long as it doesn't hit the red. Perhaps these different observations are just variations of the norm.


That's exactly what I'm trying to figure out: if it's normal for the gauge to go over the 90C mark (i.e. the actual temperature to go over 100C, as per channel 49 on the climatronic) when the engine is running and the car is not moving, e.g. in traffic, or if that is a problem. And if the latter, what could be the cause.

Thanks.


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## Charlie (Dec 15, 2006)

I think that if the gauge goes over 90C then that indicates an issue as surely the fans will cut in at 100C and bring the temp down, as such the 80-100 weighting should keep the needle on 90?

There are exceptions to this such as if you have recently been running the car and it has got hot, then you turn off the car and relatively shortly afterwards turn it back on.

I have had my car for nearly 4 years and the only time the needle has strayed from 90C is when the thermostat failed and it dropped below 90C.

I am not 100% sure what temp the fans come on at offhand so I may well be wrong, but hopefully someone can confirm or otherwise.

Charlie


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## thewolf (Jun 20, 2010)

Charlie said:


> I think that if the gauge goes over 90C then that indicates an issue as surely the fans will cut in at 100C and bring the temp down, as such the 80-100 weighting should keep the needle on 90?


My fan kicks in at around 98C, but sometimes it doesn't manage to bring down the temperature enough and if the car is not moving it goes a little over 100C. Could it an issue with the fan or the radiator? If so, what exactly?

Thanks.


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## lagmaster (Jul 7, 2011)

It sounds like you have the exact same problem I had. Read my post titled "overheating mystery solved". It might be that your car is not getting enough oil supplied to the top of the engine due to a clogged oil pickup screen. This will cause slight overheating because of increased friction and can damage your engine. Easy, but time consuming DIY if u have tools and a big hydraulic jack


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## thewolf (Jun 20, 2010)

lagmaster said:


> It sounds like you have the exact same problem I had. Read my post titled "overheating mystery solved". It might be that your car is not getting enough oil supplied to the top of the engine due to a clogged oil pickup screen. This will cause slight overheating because of increased friction and can damage your engine. Easy, but time consuming DIY if u have tools and a big hydraulic jack


Thanks for the info, if that was the case, wouldn't my oil pressure light go on?

What temperature did you car reach when sitting in traffic?

Now that you replaced the oil pick screen, does you temperature gauge ever go over the 90C mark?

Thanks.


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## lagmaster (Jul 7, 2011)

All good questions. I'll try to answer all three to the best of my knowledge 
1) My oil pressure light finally went on once after I had this problem for several thousand miles of driving. Turns out, in my case, the screen was only lightly coated with sludge, and the problem only occurred when I ran the car hot for a while, because there was some junk at the bottom of the pan that would float around faster in the hot oil and stick to the sludge on the screen, obstructing flow. Then the pressure would drop a bit, and the stuff would fall off, so the pressure would only drop momentarily--not enough to set off the light at first. And even the pressure test came out good because the only time the pressure dropped was when the car is at about 105C--which it never reached when we did the test. This is, by the way, my mechanic's theory--he admits he is not certain about exactly what was happening.
2) My temperature would slightly exceed 105 when in traffic, according to climatronic. I have the US model, and the temp gauge has no red line, but the needle would go slightly more than a notch past the middle (the middle is the 90C mark). As time went by it would struggle more and more to return to the middle when the fans went on, even though it would eventually do so.
3) Now that I replaced the screen the needle almost never goes past the middle. When it does, it is so slightly off that it is still touching the line, and then the fans go on and bring it down to the middle instantly. The temp variation is no more than 10 degrees after the car warms up (88min-98max), instead of 20+ degrees which it was before. 
One Question: Does your temp drop to WELL BELOW the middle when you drive on open highways in cold weather? If so, you probably just need to replace the thermostat again. They can go bad in just a year.


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## thewolf (Jun 20, 2010)

My 2011 180HP TT has two fans between the radiator and the engine: a smaller one on the left and a bigger one on the right.
I've noticed that when the actual temperature (as per channel 49) reaches 98C the left fan goes on, while the bigger fan remains still. Same thing when turning on air conditioning (even with cool engine): only the smaller fan comes on.

Is the bigger fan supposed to always come on together the smaller fan?

If so, something with my bigger fan may be faulty and that may explain the (small) overheating issue of my car.

Thanks.


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## Hoggy (May 8, 2002)

Hi Wolf, The 2nd fan should start at a higher temp around 104 ish I believe. Peter-ss showed a graph of fan cut-in on his Mk 1. As long as 2nd fan cuts in if temp goes higher, can't see problem. Its possible that 1st fan running will be enough to stop temp rising any more any way, so no need for 2nd fan to run.
Edit...Found the graph.
Have a look at the graph in Peters post in this topic..
viewtopic.php?f=2&t=219150&p=2053632#p2053632
Hoggy.


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## thewolf (Jun 20, 2010)

Thanks for the reply, but other forum threads state that both fans should be running together, initially at 1st speed, and then if the temperature gets really high, at 2nd speed.
Can anyone check if their fans run together or if initially just the smaller one goes on?

I think even simply turning the air conditioning should start both fans and not just the small one, like it happens on my car.

Thanks.


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## Hoggy (May 8, 2002)

Hi Wolf, Turning air con only starts the small fan, which is why if stationary in traffic after a blast & air con is on, the indicated temp on gauge rarely rises above 90 because the small fan is already running pulling cooling air through rad.
Hoggy.


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