Belt Idler Pulley
Thread Starter
MBWorld Fanatic!
Joined: Mar 2006
Posts: 3,254
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From: Louisiana
03 E500 and Corvette
Belt Idler Pulley
I have 83,000 on our E500. The belt still looked good but I decided to change it. The car is very well maintained. I found the belt Idler pulley bad when I spun it you could hear the noisy bearings. The car is under warranty and I could take it back but I ordered a new pulley and changed it. Took about 5 minutes to change it.
I would have to drive 200 miles to get warranty. You might consider checking your idle pulley. It is the small one and will have the most wear exclusive of the tension pulley.
I would have to drive 200 miles to get warranty. You might consider checking your idle pulley. It is the small one and will have the most wear exclusive of the tension pulley.
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Joined: Apr 2006
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From: Maryland
Eurocharged 2004 E500, Eurocharged ECU/TCU 2005 SL600, 2010 Caddy SwaggerWagon
I have 83,000 on our E500. The belt still looked good but I decided to change it. The car is very well maintained. I found the belt Idler pulley bad when I spun it you could hear the noisy bearings. The car is under warranty and I could take it back but I ordered a new pulley and changed it. Took about 5 minutes to change it.
I would have to drive 200 miles to get warranty. You might consider checking your idle pulley. It is the small one and will have the most wear exclusive of the tension pulley.
I would have to drive 200 miles to get warranty. You might consider checking your idle pulley. It is the small one and will have the most wear exclusive of the tension pulley.
My engine has that sound. Almost reminds me of an old school super tight radiator fan clutch. Meaning, you would goose the throttle, while idling, and you could hear the radiator fan over top of the engine sound. Some people my have ZERO idea of what I'm talking about, but I bet you do.
Hard to describe.
Thread Starter
MBWorld Fanatic!
Joined: Mar 2006
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From: Louisiana
03 E500 and Corvette
The pulley was not making noise you could hear with the engine running. I do know the type of noise you are referring.
I changed the belt then spun the bearing by hand and could hear the rollers inside. No lubricant left in the bearing and this was in early failure mode.
The new bearing was tight, no noise. IT is easy to remove the belt. 17mm socket and wratchet to back off the tensioner remove the belt from the idle pulley. Then you can easily spin it. Mine was really making noise but you could not hear it over engine. Glad I found mine,, if it fails you will throw a belt and be stuck with a break down.
I changed the belt then spun the bearing by hand and could hear the rollers inside. No lubricant left in the bearing and this was in early failure mode.
The new bearing was tight, no noise. IT is easy to remove the belt. 17mm socket and wratchet to back off the tensioner remove the belt from the idle pulley. Then you can easily spin it. Mine was really making noise but you could not hear it over engine. Glad I found mine,, if it fails you will throw a belt and be stuck with a break down.
Senior Member
Joined: Apr 2007
Posts: 311
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From: Richmond, Virginia USA
'12 E550, '10 ML350, '06 E350, '20 GLC300, '21 GLC300
I have had the same bearing go bad twice under warranty (now @ 52K). Simple test. With the engine running, carefully hold a wooden stick such as a wooden chopstick again the center bolt of the suspect pulley. If the bearing is bad, you will feel the singing vibrations in your hand. Absolutely keep it away from the moving belt. If your hand eye coordination is solid, a screw driver will work too.
Thread Starter
MBWorld Fanatic!
Joined: Mar 2006
Posts: 3,254
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From: Louisiana
03 E500 and Corvette
I have had the same bearing go bad twice under warranty (now @ 52K). Simple test. With the engine running, carefully hold a wooden stick such as a wooden chopstick again the center bolt of the suspect pulley. If the bearing is bad, you will feel the singing vibrations in your hand. Absolutely keep it away from the moving belt. If your hand eye coordination is solid, a screw driver will work too.
But then I am sure German engineering has considered all of this.
Thread Starter
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From: Louisiana
03 E500 and Corvette
The Mercedes uses an automatic spring loaded tensioner that automatically sets the tension. All you have to do is pull it back to remove the belt and install. Caution NEVER let it snap hard to the mechanical stop you might crack the supports. Took me about 5 minutes to change a belt.
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MBWorld Fanatic!
Joined: Apr 2006
Posts: 8,137
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From: Maryland
Eurocharged 2004 E500, Eurocharged ECU/TCU 2005 SL600, 2010 Caddy SwaggerWagon
Some pretty good info in the thread. I just changed my MAF and I'm doing plugs this weekend. I may just add this for good measure, since I'm sitting at 80K miles now. Also gonna do passenger valve cover gasket. Starting to get a little blow-off around it.
Price for belt and pulley?
Price for belt and pulley?
Thread Starter
MBWorld Fanatic!
Joined: Mar 2006
Posts: 3,254
Likes: 15
From: Louisiana
03 E500 and Corvette
Some pretty good info in the thread. I just changed my MAF and I'm doing plugs this weekend. I may just add this for good measure, since I'm sitting at 80K miles now. Also gonna do passenger valve cover gasket. Starting to get a little blow-off around it.
Price for belt and pulley?
Price for belt and pulley?
Also I was concerned there might be a siezed plug. After you get the plug to move about 1/8 turn loose, tighten back up a bit then loosen. Do this slowly each time comming out a small amount more. This will allow the plug to clear itself without damaging the threads. I did use never sieze for plugs but only a very tiny bit. I also used dielectric grease on the plug caps. You will have to push hard to seat the plug cap on installation. Try one on the plug wire when you have the coil out. You will see how it fits up.
Also use caution I broke a clip on the coil wire removing it.
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Joined: Apr 2006
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From: Maryland
Eurocharged 2004 E500, Eurocharged ECU/TCU 2005 SL600, 2010 Caddy SwaggerWagon
I did my plugs last week. I used the owners manual and bought those that matched the recommended parts. I bought Bosch 7422 from a MB supplier in arizona. You will need a 27mm torq to remove the coil. A 17 MM open end wrench will get the plug caps off but twist them first it will make them easier.
Also I was concerned there might be a siezed plug. After you get the plug to move about 1/8 turn loose, tighten back up a bit then loosen. Do this slowly each time comming out a small amount more. This will allow the plug to clear itself without damaging the threads. I did use never sieze for plugs but only a very tiny bit. I also used dielectric grease on the plug caps. You will have to push hard to seat the plug cap on installation. Try one on the plug wire when you have the coil out. You will see how it fits up.
Also use caution I broke a clip on the coil wire removing it.
Also I was concerned there might be a siezed plug. After you get the plug to move about 1/8 turn loose, tighten back up a bit then loosen. Do this slowly each time comming out a small amount more. This will allow the plug to clear itself without damaging the threads. I did use never sieze for plugs but only a very tiny bit. I also used dielectric grease on the plug caps. You will have to push hard to seat the plug cap on installation. Try one on the plug wire when you have the coil out. You will see how it fits up.
Also use caution I broke a clip on the coil wire removing it.
I actually installed headers a couple of weeks ago so I had to go through 95% of this process. I didn't have the plugs yet, so I couldn't leverage that opportunity. But yea, the 17mm open end wrench is what I used to pry the caps off. And since I also used dielectric grease on the plug caps, they should come off pretty easy this time. I also purchased the Bosch 7422 from autohausaz.com
It's like you're my doppelganger.
Super Member
Joined: Apr 2005
Posts: 666
Likes: 4
From: Boston, MA USA
03 E320 -wife's car now; 07 Porsche Boxster S - my toy
I have 83,000 on our E500. The belt still looked good but I decided to change it. The car is very well maintained. I found the belt Idler pulley bad when I spun it you could hear the noisy bearings. The car is under warranty and I could take it back but I ordered a new pulley and changed it. Took about 5 minutes to change it.
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I agree with you on changing the idler/tensioner pulleys when changing the belt -- it comes from my timing belt changing mentality. As you found out, the pulleys for the serpentine belt are small money, so it's worth replacing them.
BTW, have you ever changed your own ball joints in the E500? I got one done at the shop and was considering doing the other one myself since I have a shop where I work who will press fit the new joint if I bring him the steering knuckle.
Good to see you're still around and it sounds like you're enjoying yourself. Best wishes.
Regards,
paul...
Thread Starter
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Joined: Mar 2006
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From: Louisiana
03 E500 and Corvette
Hi vettdvr,
I agree with you on changing the idler/tensioner pulleys when changing the belt -- it comes from my timing belt changing mentality. As you found out, the pulleys for the serpentine belt are small money, so it's worth replacing them.
BTW, have you ever changed your own ball joints in the E500? I got one done at the shop and was considering doing the other one myself since I have a shop where I work who will press fit the new joint if I bring him the steering knuckle.
Good to see you're still around and it sounds like you're enjoying yourself. Best wishes.
Regards,
paul...
I agree with you on changing the idler/tensioner pulleys when changing the belt -- it comes from my timing belt changing mentality. As you found out, the pulleys for the serpentine belt are small money, so it's worth replacing them.
BTW, have you ever changed your own ball joints in the E500? I got one done at the shop and was considering doing the other one myself since I have a shop where I work who will press fit the new joint if I bring him the steering knuckle.
Good to see you're still around and it sounds like you're enjoying yourself. Best wishes.
Regards,
paul...
I followed your instructions on plugs. Job went pretty easy other than dropping my torq socket under the engine. Then while mirror searching promptly burned my hand on the cat.
Now we are getting the suspension alarm for too low and the car corrects. This is every time we take a drive. So now it is scheduled for warranty service again. Everytime I have had this on other cars it is air leak on shocks. Guess MB isn't ready to pony up the $$ for the warranty yet.
Thanks Paul for all your help. If you have the C clamp press you should be able to do the MB joints. Jim
Newbie
Joined: Sep 2007
Posts: 20
Likes: 0
2005 E320 CDI
Tensioner Pulley Procedure
Here is a bit of a write-up on the tensioner replacement.
http://e320cdi.blogspot.com/2008/07/...tensioner.html
http://e320cdi.blogspot.com/2008/07/...tensioner.html
Super Member
Joined: Aug 2008
Posts: 528
Likes: 20
From: Chicago IL
X166 gls450 2017
I had Chirpiing sound coming from the belt / pulley(s) while cold starting. I took it in and they replaced the V-belt and tensioner pulley. This morning I heard the sound again, though not that loud (maybe 10% of the previous one).
My question is why the noise used to go away when the engine warms up ? Also, should I suspect another pulley goin loose, Is it serious enough to take it in again (I'm under warranty another 4k miles)
thanks
My question is why the noise used to go away when the engine warms up ? Also, should I suspect another pulley goin loose, Is it serious enough to take it in again (I'm under warranty another 4k miles)
thanks
Thread Starter
MBWorld Fanatic!
Joined: Mar 2006
Posts: 3,254
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From: Louisiana
03 E500 and Corvette
I had Chirpiing sound coming from the belt / pulley(s) while cold starting. I took it in and they replaced the V-belt and tensioner pulley. This morning I heard the sound again, though not that loud (maybe 10% of the previous one).
My question is why the noise used to go away when the engine warms up ? Also, should I suspect another pulley goin loose, Is it serious enough to take it in again (I'm under warranty another 4k miles)
thanks
My question is why the noise used to go away when the engine warms up ? Also, should I suspect another pulley goin loose, Is it serious enough to take it in again (I'm under warranty another 4k miles)
thanks
Mine is under warranty but the 200 mile drive wasn't worth the effort for me. I changed mine for $25.00 and a few minutes of my time.
Super Member
Joined: Aug 2008
Posts: 528
Likes: 20
From: Chicago IL
X166 gls450 2017
Besides belt / pulley change, I also had the alignment done (both front tire Cambers was off by 1 minute), however the suspension feels 'weird' since after alignment. ... e.g. passing over a speed bump, the front suspension does not feel 'smooth', rather as if something is slightly loose (while descending the bump) ... I hate this dealership, pretty sure if I take it in they're gonna return with NTF (no trouble found) ... any advises how to tacke this & what part could possible be wrong in the suspension ?
Newbie
Joined: Aug 2014
Posts: 14
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2005 E350
Serpentine belt running slightely of idler pulley
I have a 2005 W211 E350 Mercedes - The belt tends to run slightly overlapping one of the idler pulleys. This is the plain pulley without the grooves. The belt overhangs the forward edge of the pulley. This happens even after fitting a new genuine Mercedes belt. The last one lasted 20,000 km. Eventually the belt frays on the forward edge i.e. the one that overhanging the pulley. I thought of putting washers between the pulley, where it mounts on the block, to bring it forward and into line with the belt. I assume it is out of line with the rest of the pulleys. .
Has anyone else had this problem and if so what did you do about it?
While the pulley problem has been ongoing and I have lost two belts this way, I also have a loud squeal from the motor. We sprayed Q20 in the vicinity of the front alternator bearing and the squeal went away. I assume the alternator bearing is the culprit.
Has anyone else had this problem and if so what did you do about it?
While the pulley problem has been ongoing and I have lost two belts this way, I also have a loud squeal from the motor. We sprayed Q20 in the vicinity of the front alternator bearing and the squeal went away. I assume the alternator bearing is the culprit.
Thread Starter
MBWorld Fanatic!
Joined: Mar 2006
Posts: 3,254
Likes: 15
From: Louisiana
03 E500 and Corvette
I have a 2005 W211 E350 Mercedes - The belt tends to run slightly overlapping one of the idler pulleys. This is the plain pulley without the grooves. The belt overhangs the forward edge of the pulley. This happens even after fitting a new genuine Mercedes belt. The last one lasted 20,000 km. Eventually the belt frays on the forward edge i.e. the one that overhanging the pulley. I thought of putting washers between the pulley, where it mounts on the block, to bring it forward and into line with the belt. I assume it is out of line with the rest of the pulleys. .
Has anyone else had this problem and if so what did you do about it?
While the pulley problem has been ongoing and I have lost two belts this way, I also have a loud squeal from the motor. We sprayed Q20 in the vicinity of the front alternator bearing and the squeal went away. I assume the alternator bearing is the culprit.
Has anyone else had this problem and if so what did you do about it?
While the pulley problem has been ongoing and I have lost two belts this way, I also have a loud squeal from the motor. We sprayed Q20 in the vicinity of the front alternator bearing and the squeal went away. I assume the alternator bearing is the culprit.
You will have continued belt failure until you get the pulleys all aligned. What ever the cause needs correction.
Newbie
Joined: Aug 2014
Posts: 14
Likes: 0
2005 E350
The belt is running off the tensioner pulley. On closer inspection it seems the tensioner pulley is running skew compared with the other pulleys. This would account for the problem. Has anyone else had this problem?
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Joined: Jul 2012
Posts: 1,556
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From: Canada
07 E63 + 07 CLK63CAB
Guys look into the Weistec billet pulleys,I would never replace a plastic MBpulley with another plastic pulley. When the bearing heats up nearing the 30kmark the plastic melts and then you are sitting on the side of the road, with no belt, no pulley, no power steering and no water p.ump, not a good day
Thread Starter
MBWorld Fanatic!
Joined: Mar 2006
Posts: 3,254
Likes: 15
From: Louisiana
03 E500 and Corvette
If the center pivot arm on the tensioner is worn it can allow the pulley to be misaligned with the bearings in the pulley still good. My corvette had that problem. I changed the entire tensioner because of the pivot bearing NOT the pulley bearing.
Newbie
Joined: Aug 2014
Posts: 14
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2005 E350
Belt Idler Pulley
The mystery deepens. The belt tensioner pulley bearing seems OK, there is no play, it spins freely and does not make a noise. I have now checked that it is square by using a straight edge against some of the other pulleys. It is not running skew. It looking out of line and running skew was an optical illusion created by the belt being partially off the pulley.
I have had two belts suffer the same fate. Mercedes supply 6K2398 belt. A Bosch dealer told me it is the wrong belt. The Bosch reference is 63K2404. Trouble is Bosch don't import that belt. Does anyone have any comments?https://mbworld.org/forums/images/smilies/nixweiss.gif
I have had two belts suffer the same fate. Mercedes supply 6K2398 belt. A Bosch dealer told me it is the wrong belt. The Bosch reference is 63K2404. Trouble is Bosch don't import that belt. Does anyone have any comments?https://mbworld.org/forums/images/smilies/nixweiss.gif
