2019 Leon Cupra 290 run-on pump

[RUM4MO]

Today I was lucky enough to get access to my older daughter's 2019 Leon Cupra 290, and so fitted its new air filter.

Just one question, and probably I'm being lazy, what is the coolant flow path when the electric pump is running on after a hot engine stop - in other words should the coolant get pumping into the reservoir via the small top hose - as is normal on some other VAG engines, I didn't spot any coolant flowing out of that small pipe?

Other thing, I found peanut skins in the air box below the air filter element, so, I removed the top cover of the snorkel thing - and found a complete peanut with its shell still on - nasty little mouse must have stolen some of the nuts that my daughter sees squirrels stashing "for later" - hoovered that area out using my garage hoover (James) with a washing machine waste pipe stuffed up its hose, easily big enough "mouth" to suck in that peanut while being small enough to get up into that space.

 

[SuperV8]

Have a look at self study: ssp-606 to see an overview of the EA888 coolant system.

As a general comment, I would say an expansion tank does not normally have any coolant flow - its just a high point to collect air and allow space for coolant expansion.

example:

 

[RUM4MO]

Thanks for that, I'll spend some time looking at that.

Just one generalised comment, typically VW Group cars in the past, have used that small pipe to maintain a flow of coolant through the reservoir to assist in purging air trapped in the system - in more recent times, ie while the Silicate pouches were required, things had to be done this way to assist in dosing the G13 coolant with product from these pouches.

Though that does not mean to say that the 2.0TSI 290PS system does that.

I tend to over think things until I've got a grip of them, but, my 2000 VW Passat 4Motion with the 30V 2.8V6 Audi engine, did have a run-on pump which returned coolant through that small pipe, my wife's 2015 VW Polo 1.2TSI also does the same, my 2011 Audi S4 doesn't, but, it only has an electric pump that circulates coolant around the supercharger intercooler - on demand and is driven by PWM supply - so no run-on at hot switch off under normal circumstances(apparently the plan is, if mapping that car or changing the supercharger drive pulley, is to cut one of the wires that control that pump and the system will default to run the pump at max speed always).

All I can confirm at the moment is, that there is certainly a run-on pump operating in the 2019 Leon Cupra after a hot engine switch off, which is what I'd expect.

 

[SuperV8]

This was the link I saw:

One moment, please...

In the 'general coolant' layout image I shared, you can see in the LH feed pipes there is a restriction, and the RH pipe an one way valve, so i'm sure they don't intend any meaningful flow through the header tank.

 

[RUM4MO]

Thanks for that, I've just run the coolant pump for my S4's supercharger intercoolers, and yes I can hear it running, but no coolant being returned to the reservoir - the engine was cold when I tried that, so my idea of what normally happens with all cars wrt coolant, though maybe only low volumes, getting returned to the coolant reservoir, seems to be falling apart!

I'll now check to see if I can command the electric coolant pump on my wife's 2015 VW Polo 1.2TSI to run, as it normally returns coolant to the reservoir - in fact, it seems like many people use this "function" to replace their coolant, ie disconnect the small pipe at the reservoir, join an extension length of pipe to it and direct it into a container, start engine and keep pouring fresh coolant into the reservoir until you have collected roughly 8 litres in the container connected to the small "return" pipe, stop engine, adjust level of coolant in reservoir - job completed! I'll stick with dropping the coolant out of the bottom of the radiator as doing that will allow any accumulated crap to escape as well, same for charge intercooler loop.

The trouble can be, some of these coolant paths get altered when the engine is hot, I'm checking "how things are" with a cold of just warm engine - that the same thing!