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Discussion Starter · #1 ·
The last 2 days temperatures in the UK have been around 29°C and when I first start the car I get what sounds like a short blast from an airline blowing from under the bonnet. No warning lights or anything else untoward, just the noise of a high pressure gas discharge like the car is venting excess pressure.

I’ve had a look and can’t see any tell tale signs around the hoses etc.

Anyone else experienced similar ?
 

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That would be the high speed cooling fan
 

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Discussion Starter · #3 ·
Thanks. Is that specific to Suzuki ? What’s it do as I’ve never encountered one in 45 years of driving.
 

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If the high temp switch in cooling system or engine is activated the fan turns on.. sit back, take a deep breath and relax..
 

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Discussion Starter · #5 ·
It’s not a relay or electrical sound, definitely the sound of a high pressure gas release. It only happens on the initial start of the day so I wonder if it’s a/c related. I’ll try and get someone else to start it while I shove my head (and phone) under the bonnet.
 

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I doubt it's a/c - the system doesn't hold enough refrigerant to sustain more than one or two "blasts", I doubt it's a cooling fan, you wouldn't get a gas discharge unless the air is trapped.

Isn't the boosterjet turbocharged? Can the turbo system hold pressure over night or will it leak down? I would think it would gradually loose the pressure.
 

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The turbo charger does not have the capacity to retain any pressure once the turbine stops spinning..

Maybe a sticky gate momentarily holding pressure on startup..
 

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Did some digging,, looks like the over pressure dump solenoid will purge hot air from intake pressure side on startup if ambients are above 25C to aid in engine mixture control on startup in hot conditions
 

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Discussion Starter · #9 ·
Did some digging,, looks like the over pressure dump solenoid will purge hot air from intake pressure side on startup if ambients are above 25C to aid in engine mixture control on startup in hot conditions
Thanks GV. That is more in keeping with the sound I heard and sounds like a sensible way to operate. Normally the car is in the garage so even if temps are high, they don’t hit the same levels as steel exposed to hot sunlight.

Today I had a relatively long journey (about 400 miles) planned so I turned off the a/c before I started up. Ambient temperatures still the same but I’d parked the other way around on the drive so the front hadn’t been exposed to the sun. No blow off noise but of course I’ve changed 2 factors.

I’ve backed up the driveway again today so I’ll see what happens tomorrow but it sounds like a hot weather feature we need to start getting used to over here.
 

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Discussion Starter · #10 ·
I should add that it returned 46.5 mpg (real ones not the US short measure) at a steady 70 ish mph with a/c set at 18°C (around 12°C below ambient). There’s so much to like about these cars.
 

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Discussion Starter · #11 ·
If the high temp switch in cooling system or engine is activated the fan turns on.. sit back, take a deep breath and relax..
Is the fan powered by Unicorn farts because the sound of high pressure gas and an electric motor are totally different.
 

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Is the fan powered by Unicorn farts because the sound of high pressure gas and an electric motor are totally different.
I know where he's coming from, I have a silly vehicle at work that fires up both fans as soon as the car starts for about 3 seconds, sounds like an air hose has popped off something with the nose it makes. You dont hear the motors, just the air noise. In your case tho, I suspect it's the dump valve purging the intake of hot air
 

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Discussion Starter · #13 ·
It hasn’t done it the last 2 mornings. I favour your suggestion because even though the ambient air temperature is mid to high twenties, the coolant won’t be anywhere warm enough to trigger the fan.
 
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