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Noise in front/upper engine area - 95 C220

9K views 17 replies 9 participants last post by  georgebuhr 
#1 ·
I have a 95 c220 with almost 200K miles on it...just bought it a week ago and have no idea of what maintenance was done between 100K and 200K... (I have all the original docs and books from when the first owner had it and he did everything in the books up to 100k miles when he traded it in. After that no idea...

My question...There is a rattle noise in the front upper engine area, noticeable at idle, but goes away when just off of idle. It is most noticeable when cold, but can be heard at pretty much all times if you listen for it at idle. I am not familiar with with the internals of this engine yet, but it is basically under the large cover area at the front where I assume the timing gears are. I don't even know for sure, but assume these have gears or a chain and not a timing belt??
It doesn't sound to me like a noisy lifter type of rattle, but more of maybe a tension-er mechanism or something in that area?
It there somewhere I can find a parts breakdown/diagram of this area?
Any advice.
 
#3 ·
Your belt tensioner on that car has a shock built into it. This shock is removeable/replacable. Have a look at the top mounting bolt on that shock - it is possible that there is play, which is giving you the noise at idle. It is a very common issue and very easy to solve - remove the top bolt and insert some sort of a washer or grommet and then put the bolt back into place. That little bit of extra material provided between the bolt head and the mounting flange will take up the bit of slack that is causing your noise. If you want to test the theory, use a long screwdriver to exert a bit of force on that top shock mount while the motor is running - this will take up the slack. If the noise stops, you've found your problem.

You could also replace the shock entirely. I know it is a tough job on an M104 because of very limited space. But the M111 should give you another 5 inches of clearance in the front end that will make this job easier. I know there is plenty of DIY info on this on peachparts.com
 
#6 ·
re: noise



Thanks, I found it. Sure enough, that's my problem. The bushing is worn out and it rattles at idle.

Until I got a new one, here's a temp fix for those with the same problem that seems to work. I took a sheetrock screw and drove it in about a 1/3 of an inch kindof at an angle so that the screws bites into the rubber that's still left. This takes up the slack.

The downside I see with this fix is if it happens to pop loose, the screw is going to most likely fall to the ground with someone getting a flat tire :(
 
#7 ·
I checked the top of the shock absorber on mine and it seems fine on the top end, but I can definitely feel a vibration resonating through it which seems to be coming from down at the bottom end of it....So I assume I need a tension er replacement...haven't got a round to doing it yet, will prob do it in the spring, as it is getting cool out now.
 
#14 · (Edited)
Remove the main engine fan shroud in two pieces, and you'll have all kinds of room to work on the top bolt of that shock. I was able to easily get a ratchet and extension in there by turning the main engine fan so that the gap between the blades was lined up with the bolt.

The noise is caused from wear on the rubber bushing that is part of the top mounting bolt assembly - it wears with time and you get more flexibility there - now that everything isn't together as snuggly, the movement creates the noise.
 
#16 ·
i have a 95 c220 i just picked up, has the same noise. when i put pressure against the shock then yes it does go away mostly.

so here is my question... i did try to fit a washer on the top mount of the shock but it wouldnt fit, i replaced the belt while i was at it because it needed it and put it back together and same noise..


so what do i have to replace??? just the shock part?? or the tenssioner that bolts onto the engine??? or do both need to be replaced??
 
#17 ·
Idle rattle

I replaced the shock once and the tensioner twice and the noise came back right away. If I apply tension with my fingers to the pulley bolt it does let up. Thinking about resetting the computer to possibly get a higher idle as it goes away a few rpms from where it is now. I can live with it but people ask if its' a diesel!
 
#18 ·
What happens is the shock absorber has a rubber bushing at top and bottom that bolt goes into. The hole in the bushing elongates, and get somewhat cured like that due to the heat of the engine, thus creating an elongated hole which creates play. The heat from the engine hardens the rubber bushing in that shape. The fix would be a different designed bushing that holds things solid. Not even really sure why the car needs the shock, as my Benz is the only car I have ever seen that needed the absorber on a belt tensioner.
 
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