# Loud / noisy air pump on cold start ????



## duvs182 (Aug 5, 2009)

Hi ! 

Do you have that noisy /loud sound when you first start the car. It sound like an exhaust leak and last about 20 seconds. It seem to be the air pump. Had similar issue with my old jetta 2003. Air pump that put air into the exhaust a cold start. It was failing because rivet that keep the air pump together. So air pump had a leak and make a loud sound.


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## GavinD (Jun 19, 2014)

I've commented about this before. On our car, it is a loud exhaust sound, but doesn't sound like a _leak_. All the noise appears to be coming out the end of the exhaust.

It is LOUD though. It drones inside my house pretty noticeably.


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## MisterF (Jul 26, 2018)

Could it be the Budak cycle doing its job?

Sent from my SM-N950U using Tapatalk


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## GavinD (Jun 19, 2014)

MisterF said:


> Could it be the Budak cycle doing its job?
> 
> Sent from my SM-N950U using Tapatalk


I don't believe so. Based on my experience, the Budack cycle produces a subtle growling compared to the typical even thrum of the engine noise in Otto mode. It can be heard under light loading and low RPM, especially when in Eco mode.

The secondary air injection pump is a decidedly different noise, similar to what the OP describes. There's a loud sound of sucking air under the hood, and the exhaust note has the same tone, but with a noticeable increase in volume. It shuts off a few seconds after the car has been started and never does it again until the next cold start.


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## SnakeEarl (Dec 11, 2013)

The pumps are loud. Don't worry about it unless you get a related fault code.


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## rkfast (Jun 28, 2018)

SnakeEarl said:


> The pumps are loud. Don't worry about it unless you get a related fault code.


FWIW, other brands exhibit this behavior. On cold start my wife's Mazda CX-5 sounds like the exhaust system fell off the engine. Goes away in about a minute.


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