Hi everyone,

For the past 6 months, I have been noticing a squeaking sound in the drive belt, which wasn't noticeable on the freeway but has been slowly increasing and now the whole car is vibrating at 20 mph and above. The vibration is light and seems to start at the passenger side.(Never dared to go past 30mph). I don't feel it in the steering but can clearly hear it.

Could it be because of drive belt/tensioner/idler pulley? If so, how do I test it? I tried to rev it in park but couldn't reproduce the vibration. I removed the fan shroud today (by breaking it a little, to avoid opening the fan clutch) and can see everything being tight. Can't really tell if the belt is good or not (idk how to tell). I couldn't see anything wobbling like crazy except for maybe the water/coolant pump. I was thinking to go get a 15mm socket in the morning and loosen the tensioner to remove the belt and turn on the engine to see if anything wobbles. Is it a good approach?

Also wondering it its something else thats causing the vibration.
Potential causes

• Something to do with transmission
  • Last year while doing an oil change, I stupidly drained the transmission fluid, by removing the bolt directly in the center of oil drip pan. I poured the same oil back in. So I suspect I could be a little low on ATF.
  • Every time I put the car into reverse gear, I hear a very loud cranking sound. Seems important that I should fix it right away but being a broke student, I was thinking to do it right after fixing the vibration
  • I also notice the car jerking when I take my foot off, maybe when its changing gears (Is it a spark plug issue, sorry if I am dumb)
  • (Idk how to check) Transmission mount
• Tires
  • All 4 tires are new (Michelin, less than 1 year old) but happy to check if I damaged the rims or something else
  • Last year, my car was vibrating like crazy at speeds of 60mph and above, until suddenly the rubber of one of the tires came out on the freeway and broke the back bumper. I had forgotten that I was using a very very very old spare tire. Ended up changing all 4 tires and problem was completely gone
  • Maybe I could do a tire rotation or use the spare at different positions to see if the vibration still exists
• Engine mounts
  • Car history shows they were replaces in 2017. I don't see any leaks but couldn't get a great view
• (Not sure if it cause vibration but AC stopped working new summers ago and coolant seems to be low also)

Money is really tight right now between new tires, set of 2 rotors and 2 brake pads, having to buy 2 bottles of power steering fluid because of a o ring problem, engine oil and filter in this year already. So, would like to diagnose first and buy the spare parts but very willing to put in any amount of work, even if it takes long time to learn and do. After this is fixed, I'll see about changing the ATF fluid, coolant and then spark plugs.

Any and all help is really really appreciated. Been walking everywhere for over a month now. Happy to attach pics or take videos. Here is a audio clip from inside the car. This was the sound heard during the vibration. I let my foot off gas and the vibration stopped when the speed was under 15 and started again when I went past 20.

Thank you so much in advance

 

sounds like you have loads of issues---------pick one problem go back and edit your post and list all your of what you diagnosed, ie 20mph vibration---forget about idler has nothing to do with vibration, forget about AC has nothing to do with vibration, tires dont and bla bla
engine and transmission mounts do, the drive shaft does
Put the car on a lift and run at starting vibration speed-----now what do you hear and see while inspecting the underside of the car-----bla bla

 

Thank you for the advise. It definitely sound like a good idea to focus on whats relevant first. Since I don't have a lift, maybe I can put it on jack stands and try it?

One question though. Can't a bad pulley cause a belt to slip out and make the car vibrate?

 

From what I read about your post and car, my recommendation and recommendation only, is to take it to professional, better yet, take it to the dealer. You clearly does not have any idea or know how to find what's wrong. Before you do any more damage or to spend money on you don't need, take it to professional. Now, I know you're tight on money, but as I mentioned before, doing more damage because you don't/didn't know will cost you more, dearly.

Now, I have few idea what may be causing it, but I won't discuss it here for fear of more damage. As Plutoe has mention, vibration and squeaking has nothing to do with it and I'm very certain that it's not related.

Your other choice is to cut your loss, sell the car and get something in your league. Most of Japanese cars are dependable and parts are cheap. You can always come back and get yourself another MB down the line. Our MB is not a car you count every pennies you have, or try to fix it yourself but you have no idea what you're dealing with (I'm a mechanic and still learning my E320). Unless you know what you're doing or have plenty of money, get something else.

 

I understand where you are coming from and really appreciate your advise. I wouldn't want to cause more damage either but I really love my car. I've had it for 5 years now and it only has 130k miles on it. I want to take all the right steps and fix it the right way but I want to make sure I know something is really wrong instead of replacing parts one by one.

I'm very willing to learn, even if it takes time. I will inspect the drive shaft/flex discs first (because it could cause the clanking noise when switching to reverse) and see if anything is visibly wrong. I can also check the transmission and engine mounts.

Any other advise is appreciated.

 

My advice would be, to never take an old car to a dealer. They are sure to find thousands of dollars worth of repairs, and likely don't have anyone old enough to remember how to fix a w210. What you need is an honest mechanic. They exist, but can be hard to find. They can take it for a short drive with you along and tell you what the problem is, and point out what to worry about and what can wait. You find an honest mechanic by asking a number of long time locals who they like.

My guess for a low speed vibration would be a bad wheel bearing or a tire cupping problem due to bad shocks. The clunk when shifting between forward and reverse could be normal drive line "lash" but check the drive line over to be sure everything looks good.

 

Thanks. I will check the wheel bearings. Any advise on which wheel to look for? I feel the vibration coming from the right side. I will start with the back right since that where the incident occurred on the freeway last year.
About the clunk, maybe it is a bad flex disc but idk much about it. I will update this thread. Thank you again.

 

Think very carefully about what you said and remember the comment 20mph------now wada you think???

 

Amazing restraint Plutoe. When I read his essay, I assumed you'd unload. I enjoy your comments and realize they're meant in good humor (for the most part). You've shown your bark is worse than your bite.

 

Sound advice. I get my college students something like a sound but bit older Toyota Corolla or similar Honda..even better if they can drive a stick. Since I live in Georgia, they're typically in OK shape physically and one can find a nominal and knowledgeable shop that knows how to fix them. Our old MB's, love them as we do, are just too much to keep up when you lack the skills and tools. And his tranny problem sounds expensive.

 

Thank you so much for your response. I will look into good mechanics near me.

I did try to check for bad wheel bearing by trying to rock the wheels left-right and up-down but there was no play as far as I can tell. I did notice something weird. When I am rotating the back tires manually, I am noticing a light clunk in the same area as when switching to reverse gear.

 

When you rotate the tire and hear the clunk, that's because the rear-end pumpkin is connected to driveshaft. When the trans is in either park or neutral, driveshaft don't spin. Hence car is stationary. But rear tires/wheels are connected to axle shaft, and rear axle are connected to differential, that is connected (well, not really connected, but you got the idea) to pinion gear, which is connected to driveshaft.

Normally, that clunk you hear is one of the U-joint going bad. Rear or front? I'm not sure. It's all depending on where the clunk is coming from. And don't tell us you hear it from the rear or front. Only way to check is for you to crawl under the car and listen to both front and rear U-joint. It's very are that you can tell from outside of the car. And if you hear the clunk that loud that's you're able to tell if it's coming from the front or the rear, it usually time to change the U-joint, or driveshaft right away. Normally, you'll feel the U-joint before you hear it.

Why don't you hear it when it's in drive (or reverse)? That's all depending on where the play is at in the U-joint. Now, you may get lucky by locating the used driveshaft, but that's another $$$ and if you plan to replace the U-joint, that's $$$$$ U-joint is pretty cheap, but you need to press out the old one and put in new one. And it DOES require some kind of press. Hopefully, hydraulic shop press. Your best bet is take it to machine shop and have them do it.

Lastly, as always, my experience are from other makes and models, so it may not apply to our beloved MB.

 

This is really helpful information.

I wasted today taking the belt out only to be unable to determine which of the belt/pulleys were causing the squeak. I might need to remove the radiator to get a good view. But I did get to borrow 2 additional jack stands today. So tomorrow I can lift the car on 4 sides if need be.

Tomorrow I'm planning on going under the car to see if there is any play in the drive shaft, u joints and possibly also the flex discs. I don't think the transmission mount was ever changed but I'm not sure if I will be able to get a good view. I'm currently reading through different threads and watching videos to see how other people have done since I've never lifted my car from 4 sides before. Hopefully whatever is bad turns out to be a cheaper part. I also want to drain the transmission fluid in the coming days. Will update the thread

 

There's a difference between belt squeak and pulleys making squeaky sound. From my past experience with other car, both V-belts and serpentine, IF indeed belt is causing the squeal, then it's very easy. Just change the belt. If your belt have cracks on outer edge, or look glazed, change the belt. If you have money, I would say change it anyway just to make sure but in tour case, it's bit different If one of the pulley is making noise, it's usually idler pulley. It could also be the tensioner, but that one usually is weak spring and can't hold the belt tension. So although technically, it is possible, but usually tensioner is bad spring that can't hold the tension.

Are you sure it's not like water pump or power steering pump making the noise? Or even perhaps AC compressor. As you can see, there are so many possibility that you should really take it to professional. Don't take me wrong. I give you credit for trying (or at least wanting to try), but there's just so many possibilities and you have no idea what to look for. But don't take it ti just anyone, or the cheapest place. Take it to reputable shop. They can at least tell you what's wrong. But don't buy the parts just yet. Confirm it by checking it yourself ( where the noise coming from). Then you can take it from there, if you wish.

Also, you mentioned draining the ATF, but did you know most of the ATF is in torque converter? You need to open the drain plug on the converter as well and drain fluids from there, Once that is done and you fill the trans with fluids, you need to start the car for few seconds, and few seconds only, check the fluid level and add whatever amount you need. You run it for more than few seconds, you may risk burning up the front pump due to not enough fluids. Now, you can also do fluid change without draining from converter, but you need to drain the fluid in the pan, fill it with proper amount, run the car for few minutes, stop and drain the fluid, refill again, run the car again, do this another four times and you should have almost all new fluids but there's no guarantee that it is. But that's another $$$ because you can only change three to four qt max, and you need to do this like 6 time total. Maybe (probably) more. Another $$$. Other option is of course, take it to professional and have them actually do pressure flush the system and refill it. But that's another $$$$$. addition to these, if you're not sure of the car maintenance history, you may want change the trans filter.

Can of worms getting bigger and bigger........................Do you see the $ signs now?

Lastly again, my experience are from other makes and models so these may not apply to our beloved MB.