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Mercedes 300 SEL 1991, 175K, 3.0L
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Discussion Starter #1
hello there,

yesterday i bought my very first mercedes! its a 1991 300 SEL 3.0 L with only 175K on the clock! Wow what a machine!

well all seems good except for a few minor things (for £500 there are always going to be problems, but thats half the fun !)


The first is it makes a very odd noise when the ignition is on, it sounds like a fan or something simular, but quite loud. the noise seems to be coming form behind the glove box. (the noise is also present and auidble when the engine is on)

Before i start digging aound in there is this normal ?
any ideas whats located behind the glove box?


The second issue is hopefully minor/less urgent......

the rear suspension makes a very slight knocking noise its not a big clonk but is not slilent over the bumps... suggestions of things i can check or general advice is very welcome.

thanks all

Matt
 

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Two quick thoughts:

1) possibly the blower fan for climate control? Do you have the dual controls or single pushbutton unit? What happens if you turn that off?
2) I'd check your sway bar links for the rear suspension - white (well, maybe dirty grey by now!) pieces that connect the sway bar to the wheel hub. Cheap, easy to replace, and might be your problem. If not that, maybe shocks, maybe rubber shock mounts, or other suspension items.

Best of luck!
 

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CH4S Admin , Outstanding Contributor
1985 500SEC, 1991 190E 2.6.
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40,755 Posts
hello there,

yesterday i bought my very first mercedes! its a 1991 300 SEL 3.0 L with only 175K on the clock! Wow what a machine!

well all seems good except for a few minor things (for £500 there are always going to be problems, but thats half the fun !)


The first is it makes a very odd noise when the ignition is on, it sounds like a fan or something simular, but quite loud. the noise seems to be coming form behind the glove box. (the noise is also present and auidble when the engine is on)

Before i start digging aound in there is this normal ?
any ideas whats located behind the glove box?


The second issue is hopefully minor/less urgent......

the rear suspension makes a very slight knocking noise its not a big clonk but is not slilent over the bumps... suggestions of things i can check or general advice is very welcome.

thanks all

Matt
Have you tried a forum search? The archive has a wealth of information.

Welcome, to take advantage of all the forum features, please re visit the 'Welcome to the Forum' tutorial sticky on top of the W126 page, as well as the two DIY stickies.
It will show how to search the forum (3 words min.), and has a link to the Russian MB site where you can run a VIN#.
Cheers
 

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2000 ML320 / 1988 300SE / 1985 380SE / 1969 280SE
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180 Posts
The first is it makes a very odd noise when the ignition is on, it sounds like a fan or something simular, but quite loud. the noise seems to be coming form behind the glove box. (the noise is also present and auidble when the engine is on)
With my 560SE, the aux fan was always on, which made an unpleasant fan noise whenever I turned the ignition on.
Please open the hood and check if the fan(not the clutch fan) is on when you turn the ignition on (not the engine).
If that's the case, not normal

the rear suspension makes a very slight knocking noise its not a big clonk but is not slilent over the bumps...
I would like to find out too.
 

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Mercedes 300 SEL 1991, 175K, 3.0L
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45 Posts
Discussion Starter #5
Thanks for the pointer,

I have the dual contols for the climate control, i tried turning off all the air circulation/ conditioning stuff but the noise was still there? the noise is right behind the glove box , i had a look in the engine bay last night (it was getting dark ) but couldn't see past the battery will have another look tonight.

I assume that no fans should come on with the ignition?

Will check the sway bars tonight, can you give me some pointers to what i'd be looking for?
 

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Thanks for the pointer,

I have the dual contols for the climate control, i tried turning off all the air circulation/ conditioning stuff but the noise was still there? the noise is right behind the glove box , i had a look in the engine bay last night (it was getting dark ) but couldn't see past the battery will have another look tonight.

I assume that no fans should come on with the ignition?
Correct, nothing should come on with no ignition/power. The blower fan is behind the glovebox, that's why I suggested that.

Will check the sway bars tonight, can you give me some pointers to what i'd be looking for?
Looks like this:
 

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Mercedes 300 SEL 1991, 175K, 3.0L
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Discussion Starter #7
Thanks,

if it is the blower fan it doesn't push any air out the vets until i turn it on from the center console, is this possible?
 

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Mercedes 300 SEL 1991, 175K, 3.0L
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Discussion Starter #8
right i've had a chance to have a good luck and as markusfmeyer suggested it looks like the blower fan is making the noise but it makes the noise all the time even when the blower isnt on?

the pitch of the fan changes slightly when i turn the recirculation on and off and also when i turn the blower on.

anyone ever had something like this before? any ideas?
 

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'82 Euro 500SEL, '85 Euro 500SEC AMG WB Cabriolet,'86 Euro 500SEC RUF
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Does the 300SEL have the Temp sensor blower motor? It is behind and right of the glovebox. This is the air sampler motor. They do go bad occasionally. They do run when the key is on.
 

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Mercedes 300 SEL 1991, 175K, 3.0L
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Discussion Starter #10
ahha the sampler blower motor , thats sounds like it could be the one , thanks.

Now for the questions!

why does it start when the key is on? wouldn't it make more sense to come on when the AC was on?

Has anyone removed/ repaired on of these? i'm going to give it a go tonight so any advice would be very welcome.

Do you know what fues this is on (i don't have any wiring diagrams etc ) ?

oh and finally if i remove the motor or the fuse (just to shut it up!) what will be the side affects?

anyone know of a UK parts specialist?

Sorry for all the questions but i'm going at this a bit blind! In other news i fixed my Cruise control last night!! i took the control unit out and resoldered the connections seems to have done the trick!!!

Matt
 

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Mercedes 300 SEL 1991, 175K, 3.0L
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45 Posts
Discussion Starter #12
hi,

well.... it was the sampler motor, it seems its just mounted bellow the glove box on the carpet covered shin level trim . it attached by a plastic bracket s so when it vibrates the whole thing acts like a big drum!

Is this where its usually located? should there be some rubber absorption matting surrounding it?

Thanks

Matt
 
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