C6 cooling fan normal behaviour

[Spindle]

Potentially an odd question - What is the normal behavior of the cooling fans on a C6 RS6?

I'm interested in when they come on on yours, and how often?

Having recently bought an RS6 the normal behavior is a bit unknown. Of all the ones we looked at we didn't even start two of them up due to oil leaks etc, one we road tested I didn't notice them come on but this is not to say they did or didn't.

The one we have bought, while on cold start up the radiator fans switch on for a bit and it sounds like a jet plane. They are very much 'on'. The fans then ran yesterday for a bit after a short drive too. There are no faults logged so I feel like it is normal but it seems odd they come on straight away on cold start up.

Is this correct or am I already going to have to investigate a fan issue? Complete cold start, ignition on and the fans run.

TIA

[Jim Haseltine]

Are you certain that its the rad fans running on start up? The air injection pump on my car can be very loud at times and my partner has in the past likened it to a jumbo jet.

[Spindle]

Are you certain that its the rad fans running on start up? The air injection pump on my car can be very loud at times and my partner has in the past likened it to a jumbo jet.

Now there's a thing for me to learn about then! It sounds like fans, doesn't the injection pump run all the time though? This is like radiator fans switching on and speeding up then after a while - I have not timed it - they switch off.

Next time I get a chance I'll open the bonnet to have a listen to see if I can work out where it's coming from.

[IanH755]

The Secondary Air Injection (SAI) pump fires up for the 1st 30 seconds or so on a "cold" start but once the engine is warm it'll not fire up again until the engine cools back down

If you open the bonnet, the sound comes from the front passenger side (UK cars), its very loud and is a much higher pitch than the radiator fans, almost like a Dyson hoover. The pump looks like this and it is found under the power steering Reservoir at the front passenger side -



There's also two "combi" valves, one per side, which feed that SAI air into the engine and you might be able to hear a high pitch sound coming from them as well but the SAI pump is way louder.

[Spindle]

The Secondary Air Injection (SAI) pump fires up for the 1st 30 seconds or so on a "cold" start but once the engine is warm it'll not fire up again until the engine cools back down

If you open the bonnet, the sound comes from the front passenger side (UK cars), its very loud and is a much higher pitch than the radiator fans, almost like a Dyson hoover. The pump looks like this and it is found under the power steering Reservoir at the front passenger side -



There's also two "combi" valves, one per side, which feed that SAI air into the engine and you might be able to hear a high pitch sound coming from them as well but the SAI pump is way louder.

Not been on here for a while and to be honest we've not heard the noise for a while either!

Thanks for the reply, if I hear it again then I'll nose at the SAI and see if it is that.