Audi A3 Temperature Issue (Car running cold)

Tata just called. Car will be ready @ 15:30

They just going to give it a wash for me. They tested and the thermostat is working as it should. They compared it to their Bolts and theirs is the same. Just how the Bolt is it seems, so normal for this car. At least now I can chill and know that there is nothing wrong with the car :)
 
My Polo started after 200k km to also run slightly cold in the winter. Would assume it is the valve not fully closing as it used to. Probably around 70deg now normally. Dont see it as an issue neither have I experienced a major fuel consumption increase In the summer it comes to temp easily.
 
So it has taken a while but finally got the dealership to replace the thermostat and the car is working as it should now. 5 minutes to get up to temp (90 deg) and stays there whole time. Also have noticed the fuel consumption has improved :)
 
A car cooling system is 2 loops joined via the thermostat. When it is cold water will circulate only around engine to get up to temp quick. As the temp rises the thermostat will open allowing the water to now circulate through the radiator to start cooling. If the temp drops to much the thermostat will close the water to the radiator to help raise the temp. A fan would also switch on when the temp goes higher than the set target like in standing traffic as added aid.

Different cars would run at different ideal temps. Most in the 90 degree range. Modern thermostats are designed to fail in an open position so the car would not overheat when it fails. You would notice such a failure in winter not really in summer.
Regarding another question here. The moment you have a long downhill your foot of the accelerator the ecu would not inject fuel. The wheels is actually turning the engine keeping it spinning. Thus you have no combustion but the engine is turning and water pump is moving water. So you have cooling but no combustion creating heat. So the engine would cool down very quick which is normal.
 
^very good summary

The reason why a car needs to run with the water at a certain temperature is also to help with atomisation of the fuel. If the cylinder head temp is too cold, the chance of unatomised fuel running down the cylinder walls and causing oil dilution and eventually premature wear to the rings and the cylinder bore increases.

Engineering is fun :D
 
wabbit16 said:
^very good summary

The reason why a car needs to run with the water at a certain temperature is also to help with atomisation of the fuel. If the cylinder head temp is too cold, the chance of unatomised fuel running down the cylinder walls and causing oil dilution and eventually premature wear to the rings and the cylinder bore increases.

Engineering is fun :D
Click to expand...

Also, needs to run hotter for lower emissions.
 
Ockie said:
Mine did that a few weeks ago on long road going away for the weekend. Went down a long down hill, had the car in 5th and by the of the downhill it went from 3 bars down to one bar, then after a few minutes of driving and giving petrol it went back up again. What does that mean? Problem????
Click to expand...

On overrun (when in gear and on a downhill without your foot on the accelerator), the Engine Management System shuts off fuel-flow to the injectors - so in essence your engine is not being heated by combustion, (the moving parts are kept in motion through the transmission, by virtue of it remaining in gear) so the airflow over the radiator will have the effect of cooling down the water circulating through it - once you put your foot on the accelerator again, the fuel injection re-commences and therefore combustion will then increase the engine temperature once again.
 
Unlike my first car (a 1981 VW Golf 1 GTS), which often kept the fan running for a few minutes, to cool the radiator down when you switched off the ignition and the temp gauge needle was hovering in the middle position, my current car (2008 Tata Indica LXi) immediately switches off the fan when you turn off the ignition, so I just let it idle for a minute or two, until the fan switches off, once the temp gauge has moved back down from the middle to the 1st 1/4 mark.

I also make a habit of checking the radiator expansion tank once a week, and if needed, top it up with 50/50 coolant anti-freeze.

A lot of people also tend to get overheating issues because they DON'T keep to the manufacturer recommended mix of anti-freeze & water (which varies from one manufacturer to another - check your owner's manual for the approved % mixture), which raises the boiling point of the water to above 100 deg C and thereby improves cooling efficiency.
 
Ivan Leon said:
which often kept the fan running for a few minutes, to cool the radiator down when you switched off the ignition and the temp gauge needle was hovering in the middle position
Click to expand...

I have seen so many dying batteries pushed over the edge because of this 'trick'. VW is the only manufacturer that I know of that does this, as both my old Ballade and my i30's fans turn off immediately as you turn the key back onto acc mode.

My KLR650 also keeps the fan running, and I can get it to turn on without the ignition turned on by shorting the temperature sender wire to the frame. I have also once been left in the lurch by this 'trick' a few years ago, so now I let it idle a bit to get the temp down before turning off. Talk of this issue makes me miss my old air cooled XT550 with kickstart :(
 
wabbit16 said:
Talk of this issue makes me miss my old air cooled XT550 with kickstart :(
Click to expand...

Before I became a 'cager', I learnt to ride on the first bike I purchased in 1981 - a Yamaha XT 500 'thumper' - I still have not-so-fond memories of it kicking back with a vengeance when you forgot to set the indicator correctly on the crankcase cover window with the decompress lever BEFORE hoofing it to start - I bent the rear crash-bars up quite a few times!
 
You had crash bars? Lucky :p yeah those thumpers could kick back quite a bit if you caught it on the wrong stroke.

The 550 had a nice auto decomp system that was well tuned and never once kicked back. Pity the 4-valve head design was very soft and prone to damaged valve seats and an even bigger pity I wrote it off when I was in matric :(

I often see one at the local filling station and the next time I see him I want to ask him if he would be willing to sell it. Fond memories
 
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