JoE TeE

Hey guys,

Last night I noticed that my 2010 E550 coupe abruptly began making a loud fan noise after start-up in the late evening. It sounds as if the fan was attempting to cool the engine (..1st time starting the engine for the day). I drove the car for about 20 mins to grab a bite and noticed that the fan stayed on the duration of the trip and after I shut off the vehicle. Has anyone experienced any issues like this before? The sound is comparable to a loud vacuum cleaner...as odd as it sounds..

Thanks,
JT

drey63

Mine does the same when it's hot outside. I guess it's normal to do like that because it's trying cu cool down the engine or the interior. Anyway, it sounds like a nuclear power plant

JoE TeE

My exact thoughts on the sound. Our buddy who works in the MB service dept. said that his CLS550 made a similar sound yesterday. Possibly due to the sweltering temps we are experiencing in Houston lately. My coupe was left baking in the garage for the sunday bake fest until the initial evening start-up. If the sound continues, I may possibly bring it in for service and have him take a look at it. Thanks for the info, good to know im not going to crazy listening to Zeus blowing air on the engine.

Jake94526

I kinda thought it sounded like a turbine spooling up..

calbear550

same here....doesn't matter if it's hot or cold. usually on starting up after the cars been sitting for a couple hours. doesn't happen on initial start up in the morning, but intermittently during the day if the cars sits.

a13xgh

i was having this issue with my mercedes on cold morning starts on my e cab and the dealer stated that a separate motor starts up that cools the temperature of the engine so it starts up at the correct temperature.

its a safety feature and is not an issue.

i hope this helps.

Tmaxxman

So has anyone figured out the cause My 2010 E550 is doing the same thing regardless of temp outside ?

Mr. Toad

I don't know if this applies to MB, but some BMWs did this as well, and on those cars it was often an indicator that the water pump was about to fail.

mikefalz

Code P2237 (Attached) is one of the codes that can pop up for it.
It's possible that the Coolant Temperature Sensor OR its related Sending Unit is malfunctioning. If the cars computer isn't getting a correct, or any signal at all, regarding the temperature of the engine coolant, the computer goes into a failsafe setting to ensure that the engine doesn't seriously overheat and get damaged/destroyed.

oldmots

It may be the secondary air injection pump on the front of the engine. This thing is loud and sounds like a turbine. It usually starts with the engine and runs a little bit and quits. It is a part of the emissions system.

oldmots

Just to add a little info here, the air pump pumps air into the exhaust on start up to get the converter heated up quicker to reduce emissions on start up.

Dnasty

Did anyone figure this out. I am now having a loud fan noise and constant running. It is however extremely hot right now with temps of 105 at times and 80's at night so is it related to ambient temps? My ac also just recently stopped blowing cold air and I heard that if the fan malfunctions that it will cut the compressor off as a safety precaution.