nir08

Hello, I'm new to this forum. Recently, I've purchased 2009 GL320 Blutec. It was all fine for a few miles and then I started hearing high pitched whistling / screeching sound from the engine. The dealer sold the car without warranty, so no point of going back to him (he is located in Another state, anyway). I showed the truck to a local mechanic. He charged $ 800 for replacing the drive belt tensioner, belt and some sort of pulleys. However, the sound still persists. Any clue ? The sound varies as per the speed ( and also while in neutral by raising the RPMs..so, its not a wind noise). Pl. help. I've already spent enough of money and cant drive properly because of this annoying noise. Thanks !

N_Jay

Did it get any better or different when they changed the tensioner?


If you are not mechanically incline, I would search out a local independent shop with MB experience.


$800 For a drive belt and tensioner is outrageous. Are you sure that is all they did?


EDIT:
Noise from the front of the engine can be internal or an accessory.
Accessories include; Water pump, power steering pump, alternator, AC compressor, and a few idlers and the tensioner.


A quick test it to take off the serpentine belt and start the car briefly (very briefly as the water pump is not running)


If the noise is gone then you need to start playing with each of the above list and see if one (or more) does not feel right.


If the noise still exists you need to go in deeper.

nir08

Thanks Jay,
Checked everything including belt, tensioner, alternator, water pump, compressor etc. found nothing. I suspect the noise is due to turbo exhaust, as I also smell some exhaust from the engine. The noise starts only when the engine is warmed up (after driving for few miles). I've taken an appointment with a dealer on Thursday. Anyone has clue, where I should ask them to start from (like sensor or something) ?? As, I've heard about dealer suggesting to replace to whole part like turbo or exhaust, even when its not required. I just wish to go there with some knowledge so, dealer doesn't hit me hard

nir08

The noise exists even if the car is parked. I've noticed that the noise starts only when the engine is warmed up. Appreciate, if anyone could help me with the steps on checking out Turbo and its exhaust,

N_Jay

Maybe get a contact stethoscope and start probing around.

nir08

Cant do that...Maybe, that's what you know at the best !! Thanks for your stupid (oops) suggestion.

N_Jay

Why is that a stupid suggestion?


(Are maybe the question is; "why is any stupider than asking people here to guess what problem you are having and providing the steps for you?")

alx

really?

you asked for help, a (proper) suggestion was given and you... get offensive?

good luck

BlownV8

nir08, you may not be very familiar with cars or equipment so I think your quip may have been centered around ignorance. There is an automotove stethoscope you can use to determine where the noise is located. Do a quick search on the internet and buy one. Just be careful with the rotating pieces and parts of the engine so you don't get hurt.

nir08

I sincerely apologize Jay...I didn't know about automotive stethoscope and I assumed you were just making fun of my question. Sorry..I generally try with our regular screw driver, if I want to check out the noise and had no clue about this type of stethoscope. You tried to help me and i got offended. Very sorry about it.

Update: Yesterday, check engine light came on with P0426 code ( Catalyst Temp Sensor Range/Performance Bank 1). I'm pissed of

N_Jay

Since the car is new to you, you need to get it sorted out by someone you trust.


Where are you located?

nir08

Princeton, NJ

N_Jay

Try asking here;
https://mbworld.org/forums/tri-state...nnecticut-153/
Or maybe here:
https://mbworld.org/forums/mid-atlantic-121/

drgeeforce

P042X Exhaust Catalyst, therefore:
1.Exhaust Manifold Leak. 2 gaskets~$20/pair. + labor
2.Turbocharger Exhaust Collector Pipe leak. 2 gaskets~ $9.00/pair + labor
3.O2 sensor leak. $23 + Labor


http://www.mbpartsworld.com/showAsse...sembly=1079902

bha

Are you sure it isn't the A/C?

Mine has a high pitched whine/whistle and the problem is these trucks came with A/C pulleys that fail. You can replace the pulley ($180 part) and it's difficult, or the entire compressor ($450 part) and it's easier.

To test, make SURE the A/C is off and see if the noise goes away.

The reason I say that in caps is nobody knows how to turn off the A/C properly in these trucks

Pushing the AC button so the light is off does NOT turn off the compressor. You need to turn the AC off first, then push the off button on the entire climate control. Then the AC stops running.

So hold your truck at 1200-1800rpm or so on the road or in park (wherever you hear the noise, but mine is somewhere around there). While doing so, listen for the whine, shut the AC button off, then shut the climate control completely off.

If the noise goes away, let me know and I will send you the document on replacing the pulley.

alx

the ac clutch signal is manipulated directly via the ac button on the dash. once activated the ecu decides when to disengage and re-engage the clutch based on evap coil temp, refrigerant temp and other things.

short story - you have the a/c button "off" - the ac compressor is not turning as the button is necessary but insufficient requirement for the ac clutch to engage

bha

Although the clutch disengages, something is still spinning until you shut the system off. The pulley/clutch/compressor on this truck is a bit unique so it operates differently than others.

MB specifically says when you are diagnosing pulley noises to do exactly what I said above. They tell you to shut off the A/C and then shut off the entire system.

On mine, the pulley keeps whining after you shut off the A/C. As soon as you shut off the entire system, it stops.

alx

no. the setup is ac mb-generic as they come. if yours behaves differently then there is something wrong there. turn off a/c via the button and see if cold air still comes out after 30 seconds. what you might be experiencing is a/c lock out - ie there is e predefined delay before the compressor can be shut down (and turned back on btw) to prevent short cycling. this is the only scenario when the a/c button can be ignored, but shutting down the whole system disengages the clutch anyhow and overrides the lock out.

mb specifically says to shut off the climate control altogether for simplicity of following rules in the field and to rule out the compressor lock out period.

the a/c button does just what it is supposed to do. there is no trickery there if you are not hitting the lock out period

nir08

UPDATE : The noise was due to the loose clamp on Turbo Exhaust. It is fixed, now.

Thanks guys for your support..I've learned a few great things, here.

nir08

Thanks..

drgeeforce

Your welcome. The codes pretty much tell you what's wrong.

drgeeforce

Your welcome. The codes basically tells you what's wrong, or where to start looking.

Lamont Clemons

I’m having the same issue I think whine noise then smell exhaust drive it 20 mins both goes away. What did u come up with


QUOTE=nir08;6059095]Thanks Jay,
Checked everything including belt, tensioner, alternator, water pump, compressor etc. found nothing. I suspect the noise is due to turbo exhaust, as I also smell some exhaust from the engine. The noise starts only when the engine is warmed up (after driving for few miles). I've taken an appointment with a dealer on Thursday. Anyone has clue, where I should ask them to start from (like sensor or something) ?? As, I've heard about dealer suggesting to replace to whole part like turbo or exhaust, even when its not required. I just wish to go there with some knowledge so, dealer doesn't hit me hard [/QUOTE]

DennisG01

[QUOTE=Lamont Clemons;8479528]I’m having the same issue I think whine noise then smell exhaust drive it 20 mins both goes away. What did u come up with
QUOTE=nir08;6059095]

Lamont - read through the entire thread. There's good info in there and the OP mentioned the fix, as well.