csmax

My 2012 GLK makes a "vacuum" like sound about 20 sec after starting engine and lasts for about 5 secs or so.
What is it?
My 2010 GLK did not make this sound.

csmax

40 views and nobody has this sound?

About 10 sec after starting the engine this will occur.

Sounds like an electric vac or motor and lasts for about 5 sec.

ble2716

Ask the dealer??

dmbolp

Post it on youtube so we can see if it sounds similar to what we experience?

shotgun_banjo

brake vacuum pump maybe?

csmax

Only happens when the engine cold.

venchka

The car is under warranty. Take it to a dealer. Let it sit overnight. Start it with an audience. Ask that the source of the sound be located and repaired. Come back when it is fixed.
I assume the sound happens regularly?
For what it is worth, our 1 year+ 2012 GLK with 14k+ miles doesn't make any sounds that it shoudn't. Quite the contrary. It is too quiet.

Wayne

csmax

Dealer said it is the air pump (sits on the top forward part of engine, just above the belt) comes on when cold to add oxygen to the catalytc converter.

Comes on 18 secs after start and lasts for 5 secs.

They said some are louder than others..

venchka

Thanks for the update. I guess it doesn't get cold enough at home to make ours noticeable. I'll keep an ear tuned for the sound.

Wayne

Mcosman1025

so the dealer said it is a normal thing. I just had my spark plugs replaced on my 2010 glk 350 with 133000 miles and it is making the same sound you are talking about. Goes away after the engine is warmed up. I noticed it gets louder the colder it is outside.

Mmr1

It’s not normal to be loud. Dealers do that to get out of work , lie.

Mcosman1025

why would they want to get out of work? Wouldn't they want to get more work lol. It's ridiculous how much they charge per hour for labor. All the locations near me charge around or $300 an hour

calder-cay

So, you've resurrected two threads with different issues ... this one from **2012** about a vacuum sound ... and the other from **2019** about a ticking noise.

It might have been in your best interest to start a new thread, presenting both issues you're hearing, as they might be related (maybe not ).

Mmr1

On warranty work from warranty’s they sell you as extra they loose money, right? Or why do they try to get out of warranty repairs ? They must share a burden of cost.