R320 Serpentine Belt Replacement
Thread Starter
Newbie
Joined: Jun 2009
Posts: 12
Likes: 2
From: Burlington, Vermont
2007 R320
R320 Serpentine Belt Replacement
Hey Gents,
My son and I just replaced the serpentine belt on our 2007 R320.
It's pretty straight-forward but I wanted to do a quick write-up.
I found the new belt at my local dealer and it was competitively priced with belts online (and in stock!)
First thing you need to do is remove the turbo intake. It's held on by a wacky female hex nut, an upper and lower hose clips, and two bolts to the block. Luckily I had the hex tool (T20) for it in my drill bit kit. After you remove that bolt pull out the C-clamp it was holding on.
Next, remove the large clip holding on the bottom part of the hose on the lower part of this assembly, pull the whole clip off and the hose will easily pull away.
Next remove the two bolts holding the bottom of the intake to the block. We used an 8mm socket, the lower bolt is much longer than the upper bolt.
Now you should have a pretty good view of the belt. Memorize where in goes, it's pretty easy.
Now find the tensioner pulley. Don't touch the center bolt!! Get a 17mm socket and a large socket wrench or bar. Attach this to the lower hardpoint on the pulley, now push hard counter-clockwise and this will relieve pressure off the belt so your helper can remove it from the tensioner.
Remove old belt and replace with new leaving the tensioner part to the end.
The belt removal and replacement was cake, the turbo cover was a slight PITA.
Hope this helps.
My son and I just replaced the serpentine belt on our 2007 R320.
It's pretty straight-forward but I wanted to do a quick write-up.
I found the new belt at my local dealer and it was competitively priced with belts online (and in stock!)
First thing you need to do is remove the turbo intake. It's held on by a wacky female hex nut, an upper and lower hose clips, and two bolts to the block. Luckily I had the hex tool (T20) for it in my drill bit kit. After you remove that bolt pull out the C-clamp it was holding on.
Next, remove the large clip holding on the bottom part of the hose on the lower part of this assembly, pull the whole clip off and the hose will easily pull away.
Next remove the two bolts holding the bottom of the intake to the block. We used an 8mm socket, the lower bolt is much longer than the upper bolt.
Now you should have a pretty good view of the belt. Memorize where in goes, it's pretty easy.
Now find the tensioner pulley. Don't touch the center bolt!! Get a 17mm socket and a large socket wrench or bar. Attach this to the lower hardpoint on the pulley, now push hard counter-clockwise and this will relieve pressure off the belt so your helper can remove it from the tensioner.
Remove old belt and replace with new leaving the tensioner part to the end.
The belt removal and replacement was cake, the turbo cover was a slight PITA.
Hope this helps.
Junior Member
Joined: Jun 2017
Posts: 21
Likes: 0
E350 C207
Hey Gents,
My son and I just replaced the serpentine belt on our 2007 R320.
It's pretty straight-forward but I wanted to do a quick write-up.
I found the new belt at my local dealer and it was competitively priced with belts online (and in stock!)
First thing you need to do is remove the turbo intake. It's held on by a wacky female hex nut, an upper and lower hose clips, and two bolts to the block. Luckily I had the hex tool (T20) for it in my drill bit kit. After you remove that bolt pull out the C-clamp it was holding on.
Next, remove the large clip holding on the bottom part of the hose on the lower part of this assembly, pull the whole clip off and the hose will easily pull away.
Next remove the two bolts holding the bottom of the intake to the block. We used an 8mm socket, the lower bolt is much longer than the upper bolt.
Now you should have a pretty good view of the belt. Memorize where in goes, it's pretty easy.
Now find the tensioner pulley. Don't touch the center bolt!! Get a 17mm socket and a large socket wrench or bar. Attach this to the lower hardpoint on the pulley, now push hard counter-clockwise and this will relieve pressure off the belt so your helper can remove it from the tensioner.
Remove old belt and replace with new leaving the tensioner part to the end.
The belt removal and replacement was cake, the turbo cover was a slight PITA.
Hope this helps.
My son and I just replaced the serpentine belt on our 2007 R320.
It's pretty straight-forward but I wanted to do a quick write-up.
I found the new belt at my local dealer and it was competitively priced with belts online (and in stock!)
First thing you need to do is remove the turbo intake. It's held on by a wacky female hex nut, an upper and lower hose clips, and two bolts to the block. Luckily I had the hex tool (T20) for it in my drill bit kit. After you remove that bolt pull out the C-clamp it was holding on.
Next, remove the large clip holding on the bottom part of the hose on the lower part of this assembly, pull the whole clip off and the hose will easily pull away.
Next remove the two bolts holding the bottom of the intake to the block. We used an 8mm socket, the lower bolt is much longer than the upper bolt.
Now you should have a pretty good view of the belt. Memorize where in goes, it's pretty easy.
Now find the tensioner pulley. Don't touch the center bolt!! Get a 17mm socket and a large socket wrench or bar. Attach this to the lower hardpoint on the pulley, now push hard counter-clockwise and this will relieve pressure off the belt so your helper can remove it from the tensioner.
Remove old belt and replace with new leaving the tensioner part to the end.
The belt removal and replacement was cake, the turbo cover was a slight PITA.
Hope this helps.
Hi, i have an e350 cdi which is the same engine as yours i believe. The problem i have is how do you even get to the belt. I cant even remove that black turbo intake box because there isn't enough room to get to it as the fan is in the way..
Any help would be appreciated!
Thank you
Junior Member
Joined: Jun 2020
Posts: 33
Likes: 9
From: Fairfax County, VA
2008 R320, 2002 E320
All, sorry for the late addition, but I am in the process of this repair and having some challenges. My belt gave out when the tensioner bearing died on my 2008 R320 and the whole roller axle broke off, so it was pretty obvious what to fix. I have a few questions though in working on this:
1. How do I get the black caps off of the idler pulleys to access the bolts underneath and swap them out? I have tried a few different prying tools and right angle tools and can't pop that off, and don't want to pry too hard for fear of cracking that thing. Alternatively, what's a good way to break them off, and what would be the part number for that cap? Replacement pulley didn't come with cap.
2. After the belt is on, is it common to have a bear of a time getting that black turbo intake quieter part circled in green in this thread (A 642 140 06 87) back on? I can't get those two torx bolts back up into position very easily as one person, not sure if I'm doing something wrong.
3. Is it also somewhat common that this black turbo intake piece should have a bunch of oil in it, much like the air intake pieces coming from both airboxes? I have been changing those two red rubber gaskets on the air intake connectors, though perhaps not often enough
4. It appears that the black turbo intake quieter got sliced open when the serpentine belt failed - is this a somewhat common failure as well? If I were to order a replacement, does that come with the rubber o-ring that's installed on the upper end? What is the part number for that o-ring?
1. How do I get the black caps off of the idler pulleys to access the bolts underneath and swap them out? I have tried a few different prying tools and right angle tools and can't pop that off, and don't want to pry too hard for fear of cracking that thing. Alternatively, what's a good way to break them off, and what would be the part number for that cap? Replacement pulley didn't come with cap.
2. After the belt is on, is it common to have a bear of a time getting that black turbo intake quieter part circled in green in this thread (A 642 140 06 87) back on? I can't get those two torx bolts back up into position very easily as one person, not sure if I'm doing something wrong.
3. Is it also somewhat common that this black turbo intake piece should have a bunch of oil in it, much like the air intake pieces coming from both airboxes? I have been changing those two red rubber gaskets on the air intake connectors, though perhaps not often enough
4. It appears that the black turbo intake quieter got sliced open when the serpentine belt failed - is this a somewhat common failure as well? If I were to order a replacement, does that come with the rubber o-ring that's installed on the upper end? What is the part number for that o-ring?
Last edited by doctorroboto; Feb 14, 2022 at 08:00 PM.
Junior Member
Joined: Aug 2016
Posts: 19
Likes: 2
MB R320 2009
All, sorry for the late addition, but I am in the process of this repair and having some challenges. My belt gave out when the tensioner bearing died on my 2008 R320 and the whole roller axle broke off, so it was pretty obvious what to fix. I have a few questions though in working on this:
1. How do I get the black caps off of the idler pulleys to access the bolts underneath and swap them out? I have tried a few different prying tools and right angle tools and can't pop that off, and don't want to pry too hard for fear of cracking that thing. Alternatively, what's a good way to break them off, and what would be the part number for that cap? Replacement pulley didn't come with cap.
2. After the belt is on, is it common to have a bear of a time getting that black turbo intake quieter part circled in green in this thread (A 642 140 06 87) back on? I can't get those two torx bolts back up into position very easily as one person, not sure if I'm doing something wrong.
3. Is it also somewhat common that this black turbo intake piece should have a bunch of oil in it, much like the air intake pieces coming from both airboxes? I have been changing those two red rubber gaskets on the air intake connectors, though perhaps not often enough
4. It appears that the black turbo intake quieter got sliced open when the serpentine belt failed - is this a somewhat common failure as well? If I were to order a replacement, does that come with the rubber o-ring that's installed on the upper end? What is the part number for that o-ring?
1. How do I get the black caps off of the idler pulleys to access the bolts underneath and swap them out? I have tried a few different prying tools and right angle tools and can't pop that off, and don't want to pry too hard for fear of cracking that thing. Alternatively, what's a good way to break them off, and what would be the part number for that cap? Replacement pulley didn't come with cap.
2. After the belt is on, is it common to have a bear of a time getting that black turbo intake quieter part circled in green in this thread (A 642 140 06 87) back on? I can't get those two torx bolts back up into position very easily as one person, not sure if I'm doing something wrong.
3. Is it also somewhat common that this black turbo intake piece should have a bunch of oil in it, much like the air intake pieces coming from both airboxes? I have been changing those two red rubber gaskets on the air intake connectors, though perhaps not often enough
4. It appears that the black turbo intake quieter got sliced open when the serpentine belt failed - is this a somewhat common failure as well? If I were to order a replacement, does that come with the rubber o-ring that's installed on the upper end? What is the part number for that o-ring?
2. You need some patience finding the right position of the turbo intake. Lower bolt was a bit hard to position. May be if you place bolts itself into holes without turbo intake will help you to find right angle and memorize the position of bolts with regards to surrounding parts and then replicate it.
3. Not sure.
4. A picture would better explain your problem.
Senior Member
Joined: Mar 2017
Posts: 258
Likes: 50
R320, Astro, JSW, ST4
1. They snap in, but aren't absolutely necessary. They are dust covers. You can punch through and pry them out if you're not concerned about preserving them. But they can be taken off without damage, with picks.
2. The turbo muffler is prone to leaking at the ends/seals. After having to remove and replace it many times over the past couple of years, I focus most on getting the upper oring and clip situated, before worrying about the bolts. I do the bolts from top to bottom even though the bottom one can be hard to locate if everything isn't cleaned thoroughly. The bottom bolt did not have enough length even when new, to thread completely into the tapped hole in the block - I imagine the threads in the block often get stripped from over torqueing.. The middle bolt which attaches to the base of the oil filter housing is at an odd angle and again, can easily be over torqued.
3. Yes. The crankcase vent / PCV which is at the back of the right hand cylinder head, often fails then burps too much oil into the intake. You might consider replacing it as a maintenance item. It's also possible if you have a brake booster /vacuum line leak, for the vacuum pump to be pumping excess air into the crankcase, which would then blow through this same vent too hard.
4. I can picture this happening, bakelite is pretty hard, but not like metal. The oring part number is A0279974745 (supercedes A0129979045)
Here's a page with many of the parts you're possibly interested in:
https://www.idparts.com/intake-inter...-c-29_166.html
If you only have a crack or slice in the part, you could seal it with epoxy after cleaning and sanding it, with a product like JBWeld.
2. The turbo muffler is prone to leaking at the ends/seals. After having to remove and replace it many times over the past couple of years, I focus most on getting the upper oring and clip situated, before worrying about the bolts. I do the bolts from top to bottom even though the bottom one can be hard to locate if everything isn't cleaned thoroughly. The bottom bolt did not have enough length even when new, to thread completely into the tapped hole in the block - I imagine the threads in the block often get stripped from over torqueing.. The middle bolt which attaches to the base of the oil filter housing is at an odd angle and again, can easily be over torqued.
3. Yes. The crankcase vent / PCV which is at the back of the right hand cylinder head, often fails then burps too much oil into the intake. You might consider replacing it as a maintenance item. It's also possible if you have a brake booster /vacuum line leak, for the vacuum pump to be pumping excess air into the crankcase, which would then blow through this same vent too hard.
4. I can picture this happening, bakelite is pretty hard, but not like metal. The oring part number is A0279974745 (supercedes A0129979045)
Here's a page with many of the parts you're possibly interested in:
https://www.idparts.com/intake-inter...-c-29_166.html
If you only have a crack or slice in the part, you could seal it with epoxy after cleaning and sanding it, with a product like JBWeld.
