Whirr in Engine

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Reen49
Posts: 3
Joined: Sun Oct 18, 2020 6:46 pm

Whirr in Engine

Post by Reen49 » Sun Oct 18, 2020 7:14 pm

Hi there, I'm a newbie. Just bought a 1.2 manual petrol Pulsar having had a 1.6 Audi A3 so it's a bit of a change. Not sure if it's because it's a smaller engine and it's a perfectly normal engine sound or if there's something amiss with mine but the engine makes a little whirring noise as I drive, getting higher as I accelerate and lower as I decelerate. Do other people hear this? Is it a small engine thing?
Also, when I've the heater on to demist the car in the mornings and am stopped at traffic lights, the fan seems to drop in speed for a second or two and then go back to speed and drop again maybe 10 seconds later. I had them check the battery when I bought it and they gave me a report to say it's fine but I've never heard a fan do that before. Any thoughts on either would be much appreciated.

stiyo
Posts: 52
Joined: Wed Aug 01, 2018 10:07 am

Re: Whirr in Engine

Post by stiyo » Mon Oct 19, 2020 7:35 am

It should be the turbo whirring.

If it's an automatic temperature, when you push the de mist, it should turn the flap inside the ventilation, it takes a second or two and it's reducing the fan speed and it turn on the AC compressor, when the flap is on it's position, the fan starts to full.

Reen49
Posts: 3
Joined: Sun Oct 18, 2020 6:46 pm

Re: Whirr in Engine

Post by Reen49 » Mon Oct 19, 2020 9:38 am

Many thanks for your reply Still.
Do you think that's a normal sound for the turbo to make? My old car didn't make it.

Also, the fan speed seems to drop and rise several times when stopped at the lights, not just once. It feels like there's not enough power to run it at full so it turns down and then turns up again.

stiyo
Posts: 52
Joined: Wed Aug 01, 2018 10:07 am

Re: Whirr in Engine

Post by stiyo » Mon Oct 19, 2020 10:32 am

I have 1.5 diesel with turbo and i can hear it whirring especially when i open the windows. As far as i know, it has a variable intake valve (don't know if it's a correct term), i can hear it whirring on acceleration then stabilize on cruising then whirring again on deceleration. Surely its noise are more augmented on gasoline engine.

Some cars installed their turbos on the front of the engine or side to be closer to the intake or intercooler, maybe the turbo on your old audi was installed on the front so you can't hear it whirring or it is just better isolated.

The turbo of my nissan is installed very close to the cabin more on the passenger side, naturally its noise is easier to hear.

For the fan, do the display for the fan speed reduced automatically (the speed bar) or the fan speed itself can not stay on on its speed?
Maybe check the battery voltage, the alternator voltage...

Reen49
Posts: 3
Joined: Sun Oct 18, 2020 6:46 pm

Re: Whirr in Engine

Post by Reen49 » Mon Oct 19, 2020 2:29 pm

Many thanks for your reply. Yes, I think the turbo must be installed on the driver's side near the cab so it's probably completely normal. Thanks for the reassurance. As you say, the Audi may have elsewhere.
I think the fan speed drops but the display remains the same, suggesting that it's on full speed but only blowing at half speed. I'll double-check it next time it happens.
Thanks for the advice.

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