Lose Pulley rattling & smoking belt !? help
Thread Starter
MBWorld Fanatic!
Joined: Mar 2008
Posts: 1,232
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From: Glasgow, Scotland, UK
SL 350 R230 (3.7L with AMG Speedshift autobox)
Lose Pulley rattling & smoking belt !? help
Hi Guys
This morning I started my car and seconds later I could smell burning rubber and see smoke from my engine.! When I stopped and looked in the engine, it was coming from where the belt was slipping on one of the pulleys near the left side of my engine lookind down.
There is a rattly noise and looking closer I can see that the very bottom small pulley looks to be out of line as if the bearing has worn and is not sitting central.?
If you look at the photo, I have indicated this pulley with a red rectangle. If you look at the belt you can see evidence of where the belt seems to have been worn on only half suggesting that the pulley is not straight.?
Can anyone advise if this is a tension pulley, is it easy to replace? Also I think there is only one long rubber belt in the engine so should I be replacing this ?
Thanks
This morning I started my car and seconds later I could smell burning rubber and see smoke from my engine.! When I stopped and looked in the engine, it was coming from where the belt was slipping on one of the pulleys near the left side of my engine lookind down.
There is a rattly noise and looking closer I can see that the very bottom small pulley looks to be out of line as if the bearing has worn and is not sitting central.?
If you look at the photo, I have indicated this pulley with a red rectangle. If you look at the belt you can see evidence of where the belt seems to have been worn on only half suggesting that the pulley is not straight.?
Can anyone advise if this is a tension pulley, is it easy to replace? Also I think there is only one long rubber belt in the engine so should I be replacing this ?
Thanks
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Joined: Nov 2001
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From: Boston North Shore
2001 CLK320 Cabrio
Here is the US, we do not have the CLK230 (only the CLK 320 and 430).
The part in the red rectangle appears to be the guide pulley (a.k.a. idler pulley).
Enclosed is a diagram of the belt system for your car. Note that the tensioning pulley is located under the guide pulley and a bit lower and to the right of the compressor.
For US models, the guide pulley is made of plastic with a single bearing and very prone to failure. Therefore, to avoid an inopportune and expensive breakdown/repair, since it is an inexpensive (less than $20) and very easy to replace part, many replace it as preventive maintenance.
This first thing I would check, would be for a faulty guide pulley. Check if the single long bolt, that attaches it to the engine, has worked lose or if the front or back of the pulley structure has cracks or bearing has failed (e.g. excessive play/wobble and/or bearing noise).
If so, you are lucky (e.g. averted an inopportune breakdown/collateral damage/expensive repair) and will only have to replace with a new pulley and serpentine belt (very easy and inexpensive DIY).
The part in the red rectangle appears to be the guide pulley (a.k.a. idler pulley).
Enclosed is a diagram of the belt system for your car. Note that the tensioning pulley is located under the guide pulley and a bit lower and to the right of the compressor.
For US models, the guide pulley is made of plastic with a single bearing and very prone to failure. Therefore, to avoid an inopportune and expensive breakdown/repair, since it is an inexpensive (less than $20) and very easy to replace part, many replace it as preventive maintenance.
This first thing I would check, would be for a faulty guide pulley. Check if the single long bolt, that attaches it to the engine, has worked lose or if the front or back of the pulley structure has cracks or bearing has failed (e.g. excessive play/wobble and/or bearing noise).
If so, you are lucky (e.g. averted an inopportune breakdown/collateral damage/expensive repair) and will only have to replace with a new pulley and serpentine belt (very easy and inexpensive DIY).
Last edited by Serndipity; Nov 7, 2013 at 04:30 PM.
Member
Joined: Jan 2009
Posts: 168
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From: Hollywood, CA.
2005 CLK55 COUPE
It was pretty easy really. I did it all from the bottom of the car. You will need to take off the bolts on both sides of the radiator support center piece so that you can pull the radiator forward a little due to the bolt that holds the idler pulley its pretty long. Once you unscrew this bold you will see how long it is so the idea is to pull back on the radiator and bull the idler pulley bolt out and up at the same time and it will come out fin as long as your pulling back on the radiator a bit. The tension pulley assembly just has 3 bolts from what I can remember and it straight forward it worked best for me when I did the job from the bottom of the car.
Thread Starter
MBWorld Fanatic!
Joined: Mar 2008
Posts: 1,232
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From: Glasgow, Scotland, UK
SL 350 R230 (3.7L with AMG Speedshift autobox)
It was pretty easy really. I did it all from the bottom of the car. You will need to take off the bolts on both sides of the radiator support center piece so that you can pull the radiator forward a little due to the bolt that holds the idler pulley its pretty long. Once you unscrew this bold you will see how long it is so the idea is to pull back on the radiator and bull the idler pulley bolt out and up at the same time and it will come out fin as long as your pulling back on the radiator a bit. The tension pulley assembly just has 3 bolts from what I can remember and it straight forward it worked best for me when I did the job from the bottom of the car.
Thanks for the feedback. The pulley I need to replace is the middle one in the pdf numbered as no.1 it sits below the smaller guide pulley and is about 10cm or 4" diameter is this the one you replaced?
If so did you replace the actual holder part or just the pulley wheel and is there a single nut that holds the pulley wheel on?
Thanks
Member
Joined: Jan 2009
Posts: 168
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From: Hollywood, CA.
2005 CLK55 COUPE
Hi,
I apologize for you earlier post as I just noticed that I did not read it carefully enough. I assumed you have a 320, 430, or a 55 as we do here in the U.S. Your pulley setup seems a bit different than what Im used to on my own vehicle. After taking a second look at the photo you provided, the pulley in the red rectangle looks like the idler pulley as its called here in the U.S. and not the tensioner pulley (#1 in diagram).
The idler pulley (#6 in diagram) has one long bolt that holds it in place and also has a plastic cap hiding the bolt (security torx) the tensioner pulley at least on my car see diagram (#1) has 3 bolts (allen or torx) holding it in place and one 17MM nut which is the tension bolt which is how you would loosen the tension in order to remove the belt.
I hope this helps.
I apologize for you earlier post as I just noticed that I did not read it carefully enough. I assumed you have a 320, 430, or a 55 as we do here in the U.S. Your pulley setup seems a bit different than what Im used to on my own vehicle. After taking a second look at the photo you provided, the pulley in the red rectangle looks like the idler pulley as its called here in the U.S. and not the tensioner pulley (#1 in diagram).
The idler pulley (#6 in diagram) has one long bolt that holds it in place and also has a plastic cap hiding the bolt (security torx) the tensioner pulley at least on my car see diagram (#1) has 3 bolts (allen or torx) holding it in place and one 17MM nut which is the tension bolt which is how you would loosen the tension in order to remove the belt.
I hope this helps.
Thread Starter
MBWorld Fanatic!
Joined: Mar 2008
Posts: 1,232
Likes: 168
From: Glasgow, Scotland, UK
SL 350 R230 (3.7L with AMG Speedshift autobox)
Hi,
I apologize for you earlier post as I just noticed that I did not read it carefully enough. I assumed you have a 320, 430, or a 55 as we do here in the U.S. Your pulley setup seems a bit different than what Im used to on my own vehicle. After taking a second look at the photo you provided, the pulley in the red rectangle looks like the idler pulley as its called here in the U.S. and not the tensioner pulley (#1 in diagram).
The idler pulley (#6 in diagram) has one long bolt that holds it in place and also has a plastic cap hiding the bolt (security torx) the tensioner pulley at least on my car see diagram (#1) has 3 bolts (allen or torx) holding it in place and one 17MM nut which is the tension bolt which is how you would loosen the tension in order to remove the belt.
I hope this helps.
I apologize for you earlier post as I just noticed that I did not read it carefully enough. I assumed you have a 320, 430, or a 55 as we do here in the U.S. Your pulley setup seems a bit different than what Im used to on my own vehicle. After taking a second look at the photo you provided, the pulley in the red rectangle looks like the idler pulley as its called here in the U.S. and not the tensioner pulley (#1 in diagram).
The idler pulley (#6 in diagram) has one long bolt that holds it in place and also has a plastic cap hiding the bolt (security torx) the tensioner pulley at least on my car see diagram (#1) has 3 bolts (allen or torx) holding it in place and one 17MM nut which is the tension bolt which is how you would loosen the tension in order to remove the belt.
I hope this helps.
The belt was actually very easy to change and needed just an 8mm socket to take the tension off. My engine does not have as many pulleys as yours but so long as you note the position of the belt before its easy enough to replace.
I have two belts you see, and I am now waiting for my part to arrive from Mercedes on Monday .
