Re: Serpentine belt fitting

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chesterpiglet

Active Member
Joined
Oct 8, 2008
Messages
319
Car
Mercedes W211 E280 Cdi Sport Estate
Poly V Serpentine belt snapped on Monday. I have the correct MB belt A002993429664(thanks for the help btw) & have been advised to check all the pulleys to find the cause of the failure. The 1st photo shows the old belt- it looks pretty ancient to me. I cannot find the exact belt diagram for mine(2008 W211 E280 3.0 Diesel Sport) so if anybody has it could they post it please? I found similar(photo 3) with 7 pulleys & mine has 8. Obviously the crank pulley moves & 6 all turn freely for the A/C, alternator, water pump etc but one does not turn which is the tensioner pulley(photo 2). Am I right in thinking when there is no belt on it it rests on the bracket next to it(2nd photo) preventing it from doing so(with the belt on it is held under tension in a different position?)-is this correct? The obvious thing to do is put a socket on the tensioner bolt & turn it to the left but I cannot see where this is- can you help? Photo 5 shows a pulley which spins freely but looks to be covered in "something rough"(it does look as though it could be removed though as you can see the lip of the pulley), clearly it shouldn't be like this so what's it called & how do I remove it? Photo 4 shows a part which I believe is the air intake pipe A6421400687 which needs to be removed to fit the belt, how does this come off? I'm getting grief from my French missus as to why I don't buy a modern car so I'm keen to try & do it myself. Any suggestions would be a god send. Many thanks as always. Rob.
 

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I would as I said in my previous post change the idlers and tensioner. When you wind the tensioner back there is a hole that takes a locking pin to allow you to fit the new belt. Difficult to see from the top, a new tensioner should come with a pin in place.
 
I would as I said in my previous post change the idlers and tensioner. When you wind the tensioner back there is a hole that takes a locking pin to allow you to fit the new belt. Difficult to see from the top, a new tensioner should come with a pin in place.
Is photo 5 an idler? How is it & the tensioner removed? Many thanks.
 
I think if you pop the plastic cover off the pulley you will see a tork bolt, undo that and the pulley will come off.
 

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Quick update, given the talent & workmanship on this forum that sadly I don't have everything takes me a long time to do. Torx set arrives in the post but there is no mention in the ad that it is for a 3/8ths socket & not 1/2" so I had to order some adapters(6) from TEMU. I had no idea they were coming from China but they duly arrived within a week- postage free for £7. They work & fit OK(all combinations are now catered for) so would recommend on that basis(also the delivery updates were very good & accurate). First job was to remove the air intake hose which came off quite easily. Next I tried to move the tensioner to see if the pulley wheel would turn. I have watched videos to see the force required & it appearedED60A596-580E-4D6E-A29D-C3CB924C1751.jpegF05C2A8A-A41B-4815-9B53-71AB501D0E00_1_201_a.jpeg37ED2A5B-016A-48C0-ACF3-8692100CB2F1_1_201_a.jpeg to be seized solid so I removed it & the pulley wheel is seized solid too. I have a genuine Mercedes one(A6422001370 which supercedes mine which was A64200070) arriving on Wednesday. The pulley appears to have stopped working a long time ago- how could the belt continue to power everything when not under the correct tension? Everything appears to be original to the car. The tensioner I think is dated 2005, the idler bearings 20-06-2007 & the cover May 2005- car is just coming up to 282,000 miles. Although I am a bit embarrassed I have attached the photos of what I took off. One idler pulley is covered in 2 or 3mm of rubber! I must confess to only casual examination of the belt going around & thinking "well if it's going round all must be well"! Please try & be gentle with your comments..........
 
I think that I may have mentioned the possibility of orher idlers Etc being chuffed. Looking at your photos I am amazed that anything was going round ? Was it not making any unusual noises ?
 
I think that I may have mentioned the possibility of orher idlers Etc being chuffed. Looking at your photos I am amazed that anything was going round ? Was it not making any unusual noises ?
Yes, the idlers still turned but made a whirring noise when turned. Yes, really everything worked power steering, water pump(water temp was normal), air con. I'm sure we all know the sounds(or in the case of my Isetta & 2CV smells) of our respective cars but really nothing unusual until the morning the belt failed & even then nothing loud! I really could not turn the tensioner at all, is there a bearing in the lower part because the bolt undid quite easily & did not appear to be seized on it?
 
Could anybody please tell me what size this is(the fixed nut on the bottom of the belt tensioner)? 16mm is too small & 17mm is slightly too big. Is this a TORX bolt(if so what size)or is there a special tool? On the YouTube videos it said a 17 or even 18mm socket depending on the video. Many thanks.F040D629-5D87-48AB-968B-06464AC8747E.jpeg
 
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You will need a Torx socket for that, can't remember what size you need sorry. You may find that a 12 point metric socket will do it.
 
Many thanks
 
It’s bigger than E20 which is of course the largest I have! No, my metric socket did not fit tightly enough. Hopefully someone will be along with the size although I'll have to buy more larger Torx.
 
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