Mercedes-Benz GLA Forum banner
1 - 20 of 27 Posts

·
Registered
Joined
·
79 Posts
Discussion Starter · #1 ·
I have noticed my car makes various noises hours after it is shut off. Sometimes it sounds like a tiny cooling fan somewhere in the firewall area. Some times it sounds more like a whine noise. I don't touch the car, have the key on me or even have any mbrace options. The car has the base radio.
 

·
Registered
Joined
·
816 Posts
The "hours after" throws me a bit, BUT the whine/cooling fan noise is probably the after engine shut down turbo cooling pump. Obviously turbos run hot and the bearings in the units reside in a rather brutal environment and that becomes worse when the engine is turned off and bearings sit in oil that is cooking from the heat (term is called coking)…basically a turbo creates extremely high temperatures that will cause the lubrication in the turbo bearing housing to disintegrate and causes coking. A way to avoid this situation is for the cooling oil to continue to circulate thru the turbo thus the 'whine/fan running' sound of the turbo oil pump in action.
 

·
Registered
Joined
·
5 Posts
One thing I did run into is the Can Bus activating. I was working with my Valentine One detector using their new SAVVY module for power that plugs into the OBDII port.
Something with this was being sensed by the Can Bus Network and activating things every 15 minutes for maybe 30 seconds as the Network was detecting and monitoring I am guessing a residual current somewhere, so basically the Alarm system was monitoring and slowly draining power. This was a known issue from Valentine One and they thought it did not occur on the GLA without Keyless, but I proved even on the Non-Keyless GLA it was still an issue. I have not heard if they have the Firmware resolution for Savvy yet.
If you have something external connected, it could be causing this as well. Would not see the battery drain unless you leave the car sit for days on end.
Was real easy to hear if listening to the ECU area under the hood, you could hear it kick on for aforementioned 30 seconds, then kick back off.
 

·
Registered
Joined
·
79 Posts
Discussion Starter · #4 ·
Thank you SSBGLA45 and johfinz for responding. I will try to eliminate or determine if these are the causes.

SSBGLA45 - This answer seems a real possibility. I notice my car is making no noise at my office after being parked 4 hours right now. But frequently I drive home 17 miles. Go in eat dinner, read the paper and maybe watch the news. I go back to the garage/barn with no electricity and it is making the noises. I need to verify but I think I can also go out on a Saturday morning after the car has been sitting all night and hear the noises in the morning at times. I will start recording the times and see if I can determine a pattern. But I can tell you after driving the car for 10 months pretty much the same everyday and I have no sense of a pattern and am sometimes shocked it is making noises and worry about battery life.

Johfinz - I did have a mp3 music player plugged in to the usb port continuously. I will plug it back in and see if that could have been the cause.

I think I will check if it is related to when I have my phone on me and wonder if it is the bluetooth activating in the car when I am near it. That's not it. Just checked.
 

·
Registered
Joined
·
79 Posts
Discussion Starter · #5 ·
Last night I went home and parked my car outside as I had an evening meeting. An hour later I went to the car and it was making the noise. I went to pop the hood and when I opened the driver door to access the hood latch it stopped making the noise. I pulled the hood lever, shut the drivers door and opened the hood. About 30 seconds after I opened the hood it started the noise again for about 5-10 seconds then quit.

Thoughts?
 

·
Registered
Joined
·
5 Posts
Tim,
Do you have the Keyless system or the Key solution?
is the Car Locked or Unlocked when this occurs, makes we wonder if it's recognizing the key being nearby, my Buick Regal GS which was keyless would recognize the key being in proximity and things start to come to life. I think my GLA seems to do this as well up to a certain point. If I leave it for a couple days, I have to hit a button on the Key fob to wake it back up. I had my hood open the other night and I noticed things were coming on from that as well, so I am sure it is recognizing the hood open contact and kicking the Can bus awake to monitor, but my car was unlocked sitting in the garage. Haven't tried this with Locked condition.

Just more thoughts to try and look at.
 

·
Registered
Joined
·
79 Posts
Discussion Starter · #7 ·
I think I have noticed it with the key fob in the house still I will double check that. I did not have the doors locked in the above mentioned sequence so I did not use the fob for anything. But it was in my pocket. I don't have the key less entry or whatever the key solution is that I know of.

The leaving it for a couple of days and it sleeping kind of sounds familiar to mine. I will keep testing.
 

·
Registered
Joined
·
13 Posts
After two hours in the garage, the motor area had a low "hum" eminating...Just after opening the driver door the hum stopped.

Kinda sounded like a very quiet fan,a very quiet PC muffin fan.
 

·
Registered
Joined
·
179 Posts
My CLA 250 did this. It's normal for these cars. You should hear what my GLA45 sounds like when I park it?
 

·
Registered
Joined
·
201 Posts
Most newer cars have a constant low level ecu activity 24/7. There are a lot if checks it conducts while in the off state. Most of the time it is related to the anti-theft mechanism built into the vehicle. Just checks and balances. The GLA is not too insulated as far as noise is concerned, therefore it's more noticeable than other cars.
 
  • Like
Reactions: rvittori

·
Registered
Joined
·
8 Posts
I also get this noise, happens most days about half an hour after it gets parked in the garage.
Been to the dealer twice, but of course it didn't do it and they had no idea what it was. I think the service department thought I was making it up.
In the end mentioned it to the sales rep. that we purchased from and he followed up with Merc. This is the response from them.


The noise that you are experiencing is the "Residual Heat Pump" that is designed to circulate water to cool the engine below certain parameters, this is done via a pump with a separate module to run it so it doesn't run your battery flat.
This can happen well after the vehicle has been switched off and can run anything up to 1.5 hours.


Pity the service department didn't know, would have saved me a lot of time and worry.


Trevor
 

·
Registered
Joined
·
1,407 Posts
I also get this noise, happens most days about half an hour after it gets parked in the garage.
Been to the dealer twice, but of course it didn't do it and they had no idea what it was. I think the service department thought I was making it up.
In the end mentioned it to the sales rep. that we purchased from and he followed up with Merc. This is the response from them.


The noise that you are experiencing is the "Residual Heat Pump" that is designed to circulate water to cool the engine below certain parameters, this is done via a pump with a separate module to run it so it doesn't run your battery flat.
This can happen well after the vehicle has been switched off and can run anything up to 1.5 hours.


Pity the service department didn't know, would have saved me a lot of time and worry.


Trevor
Welcome to the forum tasmerc! This is excellent information. I've heard this sound myself and wondered what it was. Appreciate your contribution to our community body of knowledge.
 

·
Registered
Joined
·
1,407 Posts
This forum has helped me out a bit, and when I saw this post and the theories, whilst I new the correct answer it was only fair that I join up and put a bit back in.


Trevor
That's what makes this a great forum! We look forward to your continued observations, there's no shortage of questions that pop up. We're all learning together.
 

·
Registered
Joined
·
84 Posts
Sorry to dredge up an old topic. I asked my dealership about the noise I was hearing, which is the same as described in this in this topic. I mentioned that I googled and found the answer provided in this topic and asked if they were in agreement.

The following is the shop foreman's reply, which seems reasonable since I have been using my AC recently. I will check out the 1 hour and the 30 minute event timing mentioned when I get a chance.

Good morning,

It sounds like what Mr. xxxxx is hearing is the blower motor for the climate control. Under certain conditions the blower motor will be activated 1 hour after the vehicle is shut down and will operate for up to 30 minutes. This is to facilitate drying of the A/C evaporator in order to minimize the risk of moisture related odor. The information from the forum is incorrect. The activation is initialized by the climate control control unit. The function will not occur if the battery charge level is low so as not to compromise the battery.

Regards,

xxxx xxxxxx
Shop Foreman, Mercedes-Benz of xxxxxxxxxx
AMG Performance Center
2015 Best of the Best Award Winning Dealership
Master Certified
Certified Diagnostic Technician
 

·
Registered
Joined
·
140 Posts
I've heard the small circulation pump, suppose to provide cooling for the turbos and bearings, protects from residual heat. Didn't know about the blower Como g on to dry a/c coils but makes sense. I'm going to leave windows down and see if when I heard the blowing I can just reach in and feel if air is coming from vents a a test. If this feature is for real it doesn't work to prevent mildew because I've had a mildew smell that needed deodorizing.
 

·
Registered
Joined
·
1 Posts
So, what you guys are actually hearing is a vacuum pump in the EVAP system. After 5 hours, if all the requirements are met, like the temp sensor reading cool enough for long enough. This vacuum pump comes on to test the integrity of the evap system. If things aren't right, then there are specific codes it sets off. The reasoning behind this, is because the the two valves in a modern EVAP system, activate hundreds of times a minute and are prone to failure after a few years. Only now, that system is depended upon for a smooth running engine. When the system is not attended to in modern vehicles, it leads to carbon buildup and expensive engine damage.

Oh, and I guess it might be some sort of heat pump, like someone else listed, but I have yet to encounter this part yet. The electric water pump in Mercedes vehicles, as far as I know, is used to pressurize the cooling system from the reservoir bottle used these days. It's one of the noises you hear when first inserting your key to start.
 
1 - 20 of 27 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top