Engine undercooling

Mines similar lol
Think its just a dodgey coolant temp semsor

Does it happen when it's cold outside but runs normal when the outside temperature is like 10-16 deg celcius or so. My 110 bhp tsi leon was the same and the cordoba is something similar as well. Just block off half your radiator with a bit of cardboard. Only really works if it's not raining as you don't want the cardboard going into mush and clogging up the radiator.

To be honest it's not really a bad thing! Mine does it aswell. Wouldn't worry about it.

I'd change the thermostat and coolent temp sender. It's not ment to do it. I've just changed both on my ibiza and fix the problem

Undercooled and overheating mean the same thing, undercooled suggests not enough cooling.

The car isn't supposed to be doing this. It could be the sender giving incorrect temps or the thermostat stuck open. Changing both doesn't break the bank,I've done this as I said both and it fixed the problem as said above.

Just to add this could and prob is affecting fuel consumption

Turbo boy your leon looks sweet. If the outside temperature is low enough then the system will not be able to get to normal operating temperature especially if your dumping what you can of it into the cabin. I would have thought that it wouldn't be preferrable in terms of engine wear as the manufacturers recommend no idling and getting the engine up to operating temperaure quickly but not not aggressively. It definately affects fuel economy. I observed this from my own experiences, very much so.

Any vag dealer eg Seat,egay,gsf,Eurocar parts etc

Pimped up vario said:

Turbo boy your leon looks sweet. If the outside temperature is low enough then the system will not be able to get to normal operating temperature especially if your dumping what you can of it into the cabin. I would have thought that it wouldn't be preferrable in terms of engine wear as the manufacturers recommend no idling and getting the engine up to operating temperaure quickly but not not aggressively. It definately affects fuel economy. I observed this from my own experiences, very much so.

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Thank you mate,its currently in winter mode and up for sale

Your thermostat is stuck open all the time therefore cooling the engine too much.
And for the sake of it, change the coolant temp sensor, buy one with the green top.
Its just too cheap not to change it

tstrahonja said:

Your thermostat is stuck open all the time therefore cooling the engine too much.
And for the sake of it, change the coolant temp sensor, buy one with the green top.
Its just too cheap not to change it

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Echo.......eeeccchoooo....echo.

Anyone else noticed and echo in here?

Echo, echo, charlie fox trot. The thermostat may not be stuck open. If it does it in the summer time, then yeah. But the winter can cause it even when the thermostat is ok just because of the heat exchange to the outside temperature.

Can I just add that it being winter will make the car take quite abit longer to warm up ;-)

but this isn't your problem, as tstrahonja cleverly pointed out your thromostat may be stuck open but you may as well change the sender at the same time as they are cheap enough if you fit them yourself.

I do think its strange people seeing there temp fluctuating like this and just ignoring it. My car was doing it when I drove home from picking it up and it drove me insane,goes to show people will spend x mount on trying to make it go faster or shiny bits but day to day running, and things get pushed aside and its a cheap thing to fix.

Need to change my thermostat, gonna do it within the next 2 weeks,

The stat is less than £10, only prob is the bloody awkward location on the engine!

Mine done that when I first got mine changed the thermostat and it sorted it there supposed to run at 90 once warmed up same as pretty much all the vag range took me 30mins to do with the right tools its easy just fiddly

I've just done my thermostat today and its 3'c outside n it doesn't cool down from 90 once warmed so is vote for a stuck open thermostat!

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Tucker157 said:

I've just done my thermostat today and its 3'c outside n it doesn't cool down from 90 once warmed so is vote for a stuck open thermostat!

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Did you do it with the inlet in place or remove it?

turboboy said:

Did you do it with the inlet in place or remove it?

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Most Defo don't take the inlet off!


Take off the water hose to the thermostat housing, take off an 8mm nut on a cable bracket on the alt and use a wobbly ended 6" extention with a shallow 10mm (single hex 3/8 preferably but I've used multi hex in the past) take out both tens, pull out old one with seal, moisten the new seal with coolant, refit thermostat (brace almost vertical) , then seal then housing, bolt it back up, cable clip back on, hose back on, slightly overfill water tank, put the cap on! Run the car, heaters off, at 2k rpm for 3 mins, then idle till the fans come on, check heaters are hot, switch car off, allow car to cool, till top rad hose has lost all pressure, then top up,



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