R320 CDI New timing chain rattle
03-08-2023, 06:14 PM
#1
Junior Member
Thread Starter
R320 CDI New timing chain rattle
Good evening,
As per title my R is showing symptoms of something I can't quite get my head around, last year (March 2022) the chain and the tensioner were replaced at an authorized Mercedes service, after it started to show the symptoms of a stretched chain (rattle on cold start up), everything worked fine until September/October, when I started to notice a very slight rustle coming from the left bank, between 900 and 1200 rpms (the one that Mercedes doesn't touch during the chain replacement). At this point the tc+tensioner had 15k km on them.
Since I was worried I brought the car to an indy shop, one that works only on benzes, we removed the left valve cover and noticed that the timing chain had some play in it, less than 1 centimeter, I mentioned this to the shop that made the repair in the first place and they said that is fine. We also replaced the filter housing gasket, it was cooked and some kind of magician repaired it using a sealant that was also obstructing one of the canals of the oil flow (previous ownership). After this intervention the noise seemed to cease and I had not much time to spend on the car.
Now, 6 months and 15k km later, I'm still in time to claim the Mercedes service&parts guarantee, indded when slightly yet quickly depressing the accelerator between 900 and 1200 rpms I hear a silent, brief yet distinctive rattle. My only explanation is that when the rpms increase the tension on the chain increases, it decreases for a moment when I leave the pedal and when I press it again, in that fraction of time, before the tensioner "interveins" again the timing chain is loose enough to slide and produce the above-mentioned rattle.
Now, I know it sound tedious and honestly hard to understand, but I hope someone will take some time to read this.
What could it be imo?
Bad tensioner
Stretched tc (already?)
Faulty/deteriorated guides
Camshaft sprocket (never heard something like this in OM642)
Balance shaft
All of the above 😵💫
TL;DR: My R makes ugly noises after an authorized shop worked on her, now they must remedy.
Thanks in advance
Francis
P.S, Please don't suggest me to bring the car to a graveyard etc., I'm really proud of my R, it's a memory of my father, and in the future she will be a garage queen.
As per title my R is showing symptoms of something I can't quite get my head around, last year (March 2022) the chain and the tensioner were replaced at an authorized Mercedes service, after it started to show the symptoms of a stretched chain (rattle on cold start up), everything worked fine until September/October, when I started to notice a very slight rustle coming from the left bank, between 900 and 1200 rpms (the one that Mercedes doesn't touch during the chain replacement). At this point the tc+tensioner had 15k km on them.
Since I was worried I brought the car to an indy shop, one that works only on benzes, we removed the left valve cover and noticed that the timing chain had some play in it, less than 1 centimeter, I mentioned this to the shop that made the repair in the first place and they said that is fine. We also replaced the filter housing gasket, it was cooked and some kind of magician repaired it using a sealant that was also obstructing one of the canals of the oil flow (previous ownership). After this intervention the noise seemed to cease and I had not much time to spend on the car.
Now, 6 months and 15k km later, I'm still in time to claim the Mercedes service&parts guarantee, indded when slightly yet quickly depressing the accelerator between 900 and 1200 rpms I hear a silent, brief yet distinctive rattle. My only explanation is that when the rpms increase the tension on the chain increases, it decreases for a moment when I leave the pedal and when I press it again, in that fraction of time, before the tensioner "interveins" again the timing chain is loose enough to slide and produce the above-mentioned rattle.
Now, I know it sound tedious and honestly hard to understand, but I hope someone will take some time to read this.
What could it be imo?
Bad tensioner
Stretched tc (already?)
Faulty/deteriorated guides
Camshaft sprocket (never heard something like this in OM642)
Balance shaft
All of the above 😵💫
TL;DR: My R makes ugly noises after an authorized shop worked on her, now they must remedy.
Thanks in advance
Francis
P.S, Please don't suggest me to bring the car to a graveyard etc., I'm really proud of my R, it's a memory of my father, and in the future she will be a garage queen.
Last edited by stars_gatherer; 03-08-2023 at 07:03 PM.
03-17-2023, 07:08 AM
#2
Junior Member
That is unfortunate. I guess the shop did just wind the new chain on? That is quick and easy with a holding tool, but then you haven't inspected the timing chain guides. You replaced the tensioner when the chain was changed, but I would start at changing it out again, preferrably with a OEM part with the latest part number. Secondly I would suspect the guides. You use MB approved oil with 229.31, 229.51 or 229.52, and change it regularly?
03-17-2023, 11:26 AM
#3
Junior Member
Thread Starter
Thanks for the response, as for the oil, the oil changes are and were regular, the car was serviced in MB until 170k km then by me with Shell Helix Ultra, 229.51 spec every 15k km.
The thing that bothers me the most is the approved mb shop saying, that in that range of rpm it's normal for the engine to make that kind of sound, as for the diagnose part, I'm also prone to thinking that the guides might be the problem, the tensioner was replaced with the chain and it figures in the invoice I received.
In June/July the car will be brought to an independent shop for a preventive oil cooler seals replacement, swirl flaps update (x8r) intake cleaning, guides, and perhaps the crankshaft bearings, as the engine will be out of the car anyways.
I wonder if this will resolve the problems.
Francis
The thing that bothers me the most is the approved mb shop saying, that in that range of rpm it's normal for the engine to make that kind of sound, as for the diagnose part, I'm also prone to thinking that the guides might be the problem, the tensioner was replaced with the chain and it figures in the invoice I received.
In June/July the car will be brought to an independent shop for a preventive oil cooler seals replacement, swirl flaps update (x8r) intake cleaning, guides, and perhaps the crankshaft bearings, as the engine will be out of the car anyways.
I wonder if this will resolve the problems.
Francis
03-17-2023, 02:35 PM
#4
Junior Member
It is very easy and cheap to change out the timing chain tensioner before you do the guides! I would absolutely do that before the guides, even if it was replaced not long ago!
The only OM642 (of many) I have been in contact with that has that sound you are describing, the chain was worn out on it, and I replaced the chain on that engine last summer. Looking at the marks on the cams, the chain was several cm streched, as the cams were many degrees off. The other OM642s I have been around does not make a sound like that. Not even a high mile (400.000 km) OM642 on a W211 I had, with original chain.
Sounds like your oil and oil changes is not to be blamed!
The only OM642 (of many) I have been in contact with that has that sound you are describing, the chain was worn out on it, and I replaced the chain on that engine last summer. Looking at the marks on the cams, the chain was several cm streched, as the cams were many degrees off. The other OM642s I have been around does not make a sound like that. Not even a high mile (400.000 km) OM642 on a W211 I had, with original chain.
Sounds like your oil and oil changes is not to be blamed!
