Fans after shutdown

[woofy]

I've been letting the car idle for a few minutes especially on hot days....or after a long run, but notice this causes the fans to come on after switching off the car for quite a while on a hot day.

I've always assumed this is normal, as any car left idling for a while tends to kick in the fans due to the lower air movement.....just from what someone said on Briskoda, I just want to check everyone else sees this?

Its always a bit of a compromise, as you should let the turbo cool down, but when there is low airmovement and the car is just sitting in a hot air at the moment, all the heat gets transferred to the radiator and intercooler, which prompts the fans where normally on a hot day you try and avoid idling.

[Lams]

These cars are fitted with secondary water pumps (electric), that are used to cool the turbo when switched off. That's why there's no need to let it idle or install a turbo timer on these cars

[brad]

I've been letting the car idle for a few minutes especially on hot days....or after a long run, but notice this causes the fans to come on after switching off the car for quite a while on a hot day.

I've always assumed this is normal, as any car left idling for a while tends to kick in the fans due to the lower air movement.....just from what someone said on Briskoda, I just want to check everyone else sees this?

Its always a bit of a compromise, as you should let the turbo cool down, but when there is low airmovement and the car is just sitting in a hot air at the moment, all the heat gets transferred to the radiator and intercooler, which prompts the fans where normally on a hot day you try and avoid idling.

My MkIV Golf used to do that. I was never quite sure what blowing a bit of air back through the engine was meant to achieve as I would have thought operating temperatures were greater than what heat soak would cause (and all the really hot stuff is shielded by the block. I figured it was something to do with crap Euro electrical plastics.

I don't bother idling down - I just drive conservatively once I get near home or wherever I'm going to. Strangely, I've never noticed the post-shutdown fans on the Skoda. I figured VW had come to their senses. I really think modern cars are beyond all that "warm-up/warm-down" shennanigans.

[brad]

These cars are fitted with secondary water pumps (electric), that are used to cool the turbo when switched off. That's why there's no need to let it idle or install a turbo timer on these cars

Yeah? Well there you go then.

So the turbo is water cooled? I'll have to pay more attention when I switch off.

[mrx]

Yeah, the fans tend to crank up for a few seconds after shutdown, especially if you've been using the aircon. The aux coolant pump kicks in to back feed water through the turbo cooling galleries, you can hear it wirring away if you listen carefully once the radiator fans have finished their bit.

[gregozedobe]

I don't bother idling down - I just drive conservatively once I get near home or wherever I'm going to. Strangely, I've never noticed the post-shutdown fans on the Skoda.

I usually slow down when I am about 3-5 minutes from my destination. When it is hot the fans seem to go for up to 30 seconds or so after I switch off, when it is cooler (ie not like it has been recently) the fans don't usually run at all after I switch off.

If I ever have to stop unexpectedly soon after I have been working the engine hard (eg stopping for roadworks near the top of a "fun" mountain pass), I always let the engine idle for a few minutes before switching off to let the turbo cool down a bit. Even though the coolant is pumped past, the oil pressure is gone, which lets the impeller shaft touch metal, and there can then be hot spots which could "coke" a small amount of oil in that critical area. Normally I don't worry about it, but a hard working turbo can get really, really hot and I am pretty conservative.

Some Skoda Octys have electrical problems (relay or controller ? ) which run the fans continuously when switched off, even after the engine is cool. This will flatten the battery pretty quickly, so if the fans don't stop before you leave it may be worth checking again in 10-20 minutes to ensure they have stopped.

[chisler]

During the recent hot spells, my fans will stay on a extra few seconds after I turned the engine off, in my RS TDI.

with this weeks normal weather they switch straight off with the engine.

[woofy]

All sounds similar to what I find. Although modern turbo engines shouldn't need cooling down, it does say to leave it a few minutes in the manual itself. On a much cooler day like today, the fans don't even run when stopping. Wherever possible, I try to drive a bit more sedately in the last bit before stopping.....

[chisler]

but you have to admit, the recent heat wave was a tad on the extreme side.

looking at the start up side of things, it normally takes my car 5 - 10 minutes to warm up, but would only take 1 - 2 minutes during the heat wave.

so maybe the fans running is a good thing? I like to think that maybe the cars smart enough to know its just to damm hot, and lets the fans run for a bit.

[Treza360]

Yep the R does this after a good run too. You'll hear the fans kick in and make a good racket in the garage even though I've locked it up and walked away. They can kick in quite a while after having walked away as well. Sometimes nearly five minutes.
Cheers,
Trent

[chisler]

Yeah, the fans tend to crank up for a few seconds after shutdown, especially if you've been using the aircon. The aux coolant pump kicks in to back feed water through the turbo cooling galleries, you can hear it wirring away if you listen carefully once the radiator fans have finished their bit.

I'm now starting to think the aircon plays a big part, with fans after shutdown.

lately I've been keeping the aircon in "econ" mode, so doesn't happen, though this evening I went to the milkbar, (which is a 2 min trip at 50kmh) I had the Aircon on "climatic" control, and got about 1 sec of fan after shutdown.
which is kinda weird I think, not like I had the engine running hot, or the turbo going.