One hellacious rattle at idle...what is it? - Page 2 - PeachParts Mercedes-Benz Forum

dieseldiehard · #16 12-03-2006, 03:48 PM

The tensioner spring has been reported weak by a few people but I've never replaced one, its usually the shock or the bearings in the tensionser wheel that usually go bad. The bearings make a grumbling noise. If your able to press the belt in 1 inch its too loose, somethings wrong.
I would remove the shock, test it by hand it should be hard to move in and out, and spin the tensioning wheel it should spin easily with no friction. These are high wear items and often need replacement, just figure how many revs they make, no lube oil except what little is sealed in the bearings, its a miracle they last more than a year

Look at the front cover on the vac pump, if its crimped over around the edges and no bolts holding it on its the early version and you should plan on replacing it.

TMAllison · #17 12-03-2006, 04:55 PM

Do yourself a favor and look at your motor mounts.

I recently had a nightmare with my 99 E300 (uses the same tensioner system your model does) where I overheated 2 shocks, melted the bushing from a 3rd one, broke a tensioner spring, stretched a belt 26mm and wore out the insides of the pivot arm ALL due to one semi-collapased motor mount.

My problems started out as noise, then vibration, then component failure.

Was very misleading (and expensive).

If you can see the top of the mount, carefully lift the engine 1/4" and see if the rubber is cracked or separating.

W Black · #18 12-03-2006, 08:14 PM

Chedk your water pump and fan clutch. My 350SDL was doing the same thing and I found the fan clutch bad with excessive side play.

Full Monte · #19 12-04-2006, 06:51 PM

You guys are great!

I'll take your advice. I know exactly what to do now. I will report back what I find out. Thanks again!

sublettm · #20 12-04-2006, 08:09 PM

I had no idea a worn motor mount could do that kind of damage. My 87 is also making this type of noise and just started doing so a few weeks ago. I know teh entire front end of my car needs replacing, just haven't had time to do so. I know it can't be teh tensioner and such on my car as this was just done about six months ago. I also know it isn't the water pump on mine since I replaced it about 10 months ago. I guess it is time to bite the bullet and replace the worn ball joints, tie rods, drag link, shocks, motor mounts, and every other part I have no desire to replace. The kicker of all of this is that I just finished replacing all of the above on the wife's 84 300D a couple of months ago. What did I do to deserve having to replace the front end components on two cars in a year? The bad part is that I have to pull the springs to do all of this on the 87...or so I gather from reading all of the posts on the subject. Anyone know how much Performance Products charges to rent the spring compressor? I'm not even going to suggest that I am going to use any other compressor than the one intended to do the job properly. For those of you who have replaced ball joints on both the 124 and 123, how similar are the jobs?

Brian Carlton · #21 12-04-2006, 08:18 PM

Quote:

Originally Posted by sublettm

Anyone know how much Performance Products charges to rent the spring compressor?

IIRC PP charges $75.

But, you, since you are a well respected member of our community, can rent the identical spring compressor from one of our forum members for a price of $30.

sublettm · #22 12-04-2006, 08:32 PM

I don't know about well respected, but I am definately a glutton for punishment as I keep doing these awful repairs myself. I keep telling myself that I will eventually fix everything wrong with these two cars and won't have to devote every weekend to fixing something. I am starting to think that by the time I fix everything, the parts I replaced will start to break again and I'll start from the top. The wife's car REALLY needs to have that little seal replaced that goes from the turbo drain line into the oil pan. I have been avoiding this little repair for a couple of years now as I was scared senseless after reading the posts on this subject. How can a two dollar part be that big of a pain to replace?

I really hope I enjoy the ride of the 87 once the suspension parts are replaced. There was a brief, very brief, time when I enjoyed driving this car. It lasted for about a month, then things started going wrong. The engine is strong, it has lots of power, but the suspension parts almost make it embarassing to drive with all of the squeeks and groans. If what was said is true, I need to get off of my rear and replace all of this since the last thing I want to do is replace the tensioner again. That was a royal pain in the but and I think I recall losing my religion, and a few years off of my life, that day.

Brian Carlton · #23 12-04-2006, 08:35 PM

Quote:

Originally Posted by sublettm

If what was said is true, I need to get off of my rear and replace all of this since the last thing I want to do is replace the tensioner again. That was a royal pain in the but and I think I recall losing my religion, and a few years off of my life, that day.

.........well, you already know the alternative to wrenching on old M/B's.........

.........if you need a hint.........it begins with an H.

Full Monte · #24 12-24-2006, 12:21 AM

OK...here are the results. After living with it, I determined the noise was coming from two sources...the vibration dampener AND the alternator. Once the serpentine belt was off, I spun the alternator by hand. It made the sound of dry bearings. So, after replacing the alternator and the dampener, the car runs very quiet now. Thanks for all the help on this, guys. I'm sure some of the other noises listed are possibles in the future, but not this time.
Thanks again!

JohnPeter · #25 12-30-2006, 07:54 AM

Is there a vibration dampener in a 1980 MB 240D? My Dad's car vibrates terribly at low RPMs, such as those observed at idle, with automatic transmission in "drive."

Thanks in advance.

I appreciate Full Monte's follow-up!

mbenzer · #26 12-30-2006, 10:25 AM

For what it's worth here guys after the fact, my 300D Turbo developed a knock that worsened over time and given all that I've read here about diesels in cold weather, I wasn't too alarmed. Then, when my wife wouldn't drive the car anymore, I decided to take a closer look. I still could not come up with anything. The next morning I decided to drive it down to my MB mechanic and I wasn't 4 miles away from home when I heard a loud bang and looking out of my rearview mirror I saw parts flying out of the back end of my car. Scary stuff. It was my main pulley! Two bolts were broken off in the damper, two bolts were completely missing and two bolts were holding a piece on the engine.