new_mb123

Hello, when I startup my car (CLK 320 03) in morning, there's a strange rattling noise... I've got a feeling it's something behind the COMAND console. Anyways, after about 5 minutes once the car heats up the noise goes away.

I've seen a few posts regarding rattling noise, but not sure whether they apply to CLK. In any case, I will be looking behind COMAND on the weekend, but if someone else had/has a similar problem do let me know.

Thanks!

lkchris

Just deductive thinking would suggest it has something to do with the heater, i.e some bearing shaft lubrication gets stiff when cold, some vacuum-operated door malfunctions, something like that. These are really the only moving parts under your dash. Although coolant moving through heater lines can be "bubbly."

new_mb123

Thanks, lkchris.

I've looked into the issue today, but didn't manage to solve it.

Here's the problem: once I unlock the car, but before I start the engine, something behind COMAND starts making this strange rattling noise.

My suspicion was that it's something in the NAV drive in comand, but I tried it with both a disc inside and empty - the noise remains.

Problem disappears after about 10 minutes of driving, once the car heats up. So, it is something with the heater... I doubt it has anything to do with the doors since the noise clearly comes from behind the COMAND.

I've replaced water with anti-freeze just in case it was causing problems.

Anyway, can lkchris or anyone else give me a few hints/links that might give me some further suggestions on what to try? (I'm a newbie to cars in general and MB in particular).

new_mb123

Just a quick add-on, I was checking this thread:
https://mbworld.org/forums/showthrea...t=heater+noise

But my noise is different, and what's important i can hear it before starting the engine. My noise is kind of rattling, as if a small piece of plastic has come off... but the noise disappears, which suggests that everything inside is alright... :?

Diesel Benz

Could it be one of those heater air flow control actuators? I believe on a C-class at least those have failed.

Edited: this car still appears to have vacuum controlled flaps, should not be the above issue then.

Do you mean you only open the door, or do you also switch ignition on?

I'm not sure if the small interior temp sensor fan would start before ignition is switched on, I don't think so.

Diesel Benz

I started wondering what did you mean with the above? You could not have water (instead of a mix of water and coolant) in the cooling system? I don't see how the windshield washer could be connected (there I could understand one using pure water, even if this isn't the best even at non-freezing temperatures.

new_mb123

Diesel_Benz, I mentioned the anti-freeze windscreen washing liquid because where I am the temperature goes down to -25 C over the night and I don't have a garage. So, my first suspicion was that I left too much water overnight and so the ice expanded and that lead to plastic making some noise... quite a story

Anyway, I put in a whole bottle of anti-freeze now so there isn't much water but the noise persists... so, I guess it's something else.

I've been reading other threads and there was an old (2004) post with some similar problems... I now also hear whistling noise when turning heater in the morning. Those threads don't post any solutions, so it's probably 'normal'... as in, tech people don't consider it significant enough to solve..

Diesel Benz

-25 Celsius, there isn't a place that cold this time of the year? If it was, you might start hearing a lot of unusual plastic noise, but it shouldn't be the rattle you describe.

A frozen washer pipe could make some noise but those are all at the engine bay or the hood and the sound should not appear inside.

Did you already try to take the Comand unit out? Perhaps the source would come more obvious. Comand should have a cooling fan, gyros and the CD(/DVD) drive, did you have a disc in the unit?

I wish you luck with the fix and hope the temp reading was an error, not that nice to work in the car if it is really cold.

whoover

Nowhere?

http://uk.weather.com/weather/local/...code=code&y=15

Diesel Benz

I said nowhere, that is nowhere

But I doubt an MB would be driven at that place.

grane

I had a similar noise in my Gwagen in the same location and they replaced the HVAC system stepper motor and some wiring. Thank gd for extended warranties. Suggest that to them...might be something similar.

Grane

new_mb123

Thanks for the feedback!

Yes, it does get that cold in Russia and CLK is really not the best choice for this kind of climate. In the mornings it takes about 10-15 minutes to warm up the car and what I find somewhat alarming the displays change very slowly when the car is cold (I mean the displays behind the wheel. Comand works fine.) Once the car heats up both the noise goes away and display works slowly.

And as for Grane's comment, that probably is the solution to my situation.. except I bought the car used (in Germany) and doubt I will get warranty honored here. Usually, we're charged for just about anything

webada

under extreme cold temp, the parts might be contracted enough to be loose... this explains your rattling noise in the morning. The same goes with the display, Liquid crystal will reponse slower under extreme temp.

i've seen cars when under cold temp, the windshield rattles before the car was warmed up.

grane

So if it's the stepper motor it is just defective. The cold may make it worse since parts may contract but it may make it better also since parts may contract - and NOT rub.

Good luck,
Grane

new_mb123

Thanks for the feedback. I'm kinda used to the noise now, although slightly disappointed. My previous car - Toyota, was working very well under this weather without any noise. But there isn't much I can do aside from paying to replace the parts, which I will need to postpone until next fall.

On a related note, there are contradicting claims on the net regarding warming up cars in winter (that is letting the engine work for a while, before taking off). Now, in my official Toyota handbook it was written that it is NOT recommended to 'warm up' the engine, but rather begin driving slowly.

I wasn't able to find a similar note in MB handbook, so can some experienced user tell me: under such temperature extremes am I damaging the engine by letting it run for about 10 minutes before taking off?

Diesel Benz

First, at -25 Celsius or lower, you should be sure you have 0W-xx (MB approved) oil, like 0W-40. Then let the car idle a few seconds to be sure oil pressure is OK and oil starts flowing in all parts of the engine. Then start driving, but very slowly and carefully at reasonable RPM and slowly increasing load.

The problem with idling only is that the engine would generate very little heat with no load and there is a lot of water in exhaust gas that starts condensing and remains in the engine, spoils the oil and then lubrication stops working...

I would certainly use a block heater or a fuel heater to warm up the engine a bit first (say to 0 Celsius or above). Still you would have to drive carefully first as the tranny and the suspension and everything else is cold.

It would be important to run sufficiently long with a fully warmed up car at least frequently if not every time.