Ok gents.

This is my C43 that's NOT been in a wreck.

Since I bought it, I noticed a slight ticking sound that was relative to the speed of the car (not the engine speed). Most noticeable on takeoff, and wouldn't always occur. Sometimes it would happen, sometimes it would not. I first thought it was a wheel bearing or something, but then I became convinced it was related to motor mounts or transmission mount, because the sound appears to be coming from the center of the car, from behind the dash and downward, it sounds like.

It would only do it when I was accelerating in any way. The minute I released the gas pedal, (like to coast or come to a stop) it would go away.

Ordered new motor mounts and transmission mount. Replaced drivers side motor mount and tranny mount. Could not break loose the top bolt on the passenger side mount. Still, I figured 1 mount + tranny mount would be enough to make a dent in the issue until I could get that top bolt loose on the other mount.

I was wrong. Problem persists, and is WORSE now. Now it's louder, more intense, and does it even when my foot is not touching the accelerator. I'm at a loss.

Youtube video attached:

 

have you checked centre shaft bearing and your flexdisc's?
it could be anything from trans to wear and tear parts on centre shaft?
good luck finding the issues.

 

juding by the location of the sound, i've ruled out it's definitely not the rear flex disc.

it does sound like it's coming from the front flex disc area, but it looks brand new. no cracking, no flaking, no parts sticking off or exposed threads.

I also doubt it could be the center bearing, because it sounds like it is too far forward, but I could be wrong. I'm further perplexed by the fact that it got WORSE after all the work I did today

PS
All these comments about the bolts being easy to remove on motor mounts were BS for me. The top bolts were a freaking nightmare. No room to work, and once I get the ratchet onto the bolt, I have no room to put much power into breaking it loose. That's why I couldn't get the passenger side mount off.

 

There are some alloy insulating covers above the driveshaft, for sound conceal & Exhaust heat insulation,,

did you check it, it may loose & the driveshaft hit it when the car running...?!?

ZAYED,,

 

I looked around and couldn't see anything potentially hitting the flex disc or drive shaft.

I just drove down the street back and forth for a bit trying to listen closely to where the sound was coming from, and it sounds like it is a bit farther back than I originally thought. Now I seem to hear it more behind the gear shifter area. Maybe it really is the support bearing? Got worse because updating the mounts changed the angle of the driveshaft hitting the bearing?

 

Do you have any kind of vibration between 20-90mph....??

ZAYED,,

 

Ive only driven the car that fast once the day I drove it home. I can't remember if it vibrated.

I know my silver one has a vibration that's likely the center support bearing.

Any one got any ideas as to all likely possibilities? Need to order parts asap, and is this a part I can diy?

 

Definitely sounds like something jammed in there. I had a sound sort of like what you had (coming from drive shaft area, wasn't wheel bearing, went with speed not rpm) and I think it took some digging, but either it was hitting the heat shielding, or something had gotten jammed in there like a stick or something. Also the insulation around the tunnel was pretty ripped up.

 

+1,

Prefer to investigate it more & more, before spending $$$,

try to remove the driveshaft assembly, to check it well, and see carefully all the area around it....

ZAYED,,

 

To me it's a "deep" sounding noise (rumble) which doesn't seem to come from something stuck or hitting a turning part. I conclude it could be drive train related or worse something in the transmission. Have you been to a knowledgeable shop for an opinion?

 

It definitely isn't metal hitting metal. It's way too soft for that. Sounds like metal and plastic or rubber. Doesn't shake the whole car and can't be felt through the steering wheel. I can just barely feel it through the shifter. I'm more certain it's drive shaft related, because it does it when the car is rolling but even when the transmission is in neutral (disengaging the transmission from rear wheels).

 

In retrospect, the previous owner said he hadnt noticed the noise. He also only put 200 miles on it because he got afraid of it becoming a moneypit.

The oil leak in the front caused a brand new serpentine belt to failed which was shredded all over the front and bottom of engine compartment. I suppose it could be a piece of that belt is caught somewhere farther back on the driveshaft and is slapping the car? I've inspected it but haven't spotted anything, but I can't inspect it properly with the exhaust in the way. Looks like I'm at least dropping the exhaust and inspecting.

Anyone done any DIY work down there? I'm mainly concerned with how difficult it is to remove the flex disc bolts. Those things look HUGE and I only have hand tools and ramps.

 

Flex disk bolts were surprisingly easy for me. They're big but they shouldn't take too much to break loose. Just turn the driveshaft so the bolt you're working on is the most accessible. And be careful to not strip the bolts, I think I used a monkey wrench on one end because I only had 1 socket that was big enough.

 

I went out and dug and inspected as best I could without taking it apart (my bones and muscles are aching from tinkering on it all day sunday) and couldn't find a damn thing.

Drove it around and listened as best I could. Sounds like its coming from the center-right of the console. Flex discs look brand new.

I'm having a horrifying thought that it could be the transmission? Is that even possible? The transmission shifts and grips completely normally and exhibits NO signs of trouble. I've even done a few full-throttle starts from a dead stop just to test it. If it's the transmission, I'm in serious trouble and this car will be sold.

 

If the T/converter clutches goes bad, loady clicky sound will appears,,

as well as tranny, it has "2" driveshafts, input & output, those driveshafts causes a damn horrible sound if their bearings & seals goes bad,

i hope you don’t forcing these issue...!!

ZAYED,,

 

I would definitely get the vehicle checked by a reputable workshop which knows these vehicles before doing anything else. I still feel that is is tranny of shaft related...
In the worse case scenario and you need a new tranny, contact these people: http://mercedesdismantlers.com/index.html
We had a thread on transmission problems recently. See here: https://mbworld.org/forums/c36-amg-c...placement.html

 

Agreed & prefer that...

ZAYED,,

 

I want to try and rule out the transmission (for obvious reasons)

I'm tempted to think it's not the transmission for the following reasons:

Before the motor mount/transmission mount swap, the problem was not as bad, and was intermittent. Sometimes it would do it, sometimes it would not. I changed 1 motor mount and 1 transmission mount and now the problem is worse and constant. Changing the mounts would not affect the transmission in any way, right? But it WOULD change the angle of the drivetrain/driveshaft from front to back of the car, making a bad center support bearing even worse?

Also, it does the problem even with the car in neutral. I even tried it with the car in neutral and the engine OFF and I could still hear it (I put the rear wheels up in the air, put it in neutral, and used lug wrench to spin rear wheels as fast as I could with my foot). I have a feeling that would mean it's likely not the transmission?

 

You need to drop the exhaust and heat shields and inspect in the drive shaft area. My bet is the u-joint on the rear shaft. When you installed the new mounts and changed the angle it just aggravated the already failing joint. it's an Internet guess but I'd stake a beer it's in that area. .02

 

How many miles on the car? I just had to have the driveshaft reconditioned on my 2000 C280 because the driveshaft u-joint had worn in the running position, making it "notchy". The symptom was a vibration much like you get when the center support is defective as the car shifted into 2nd gear and a clicking sound when applying/releasing the throttle. That started happening about 150,000 miles. I had another C280 that went 254,000 miles without any issue, so it seems to vary by car. Also, I could not see/feel the problem until I pulled the driveshaft out of the car. The u-joint is not considered replaceable - M-B doesn't sell the part and getting the dimensions of the joint itself isn't easy. Also, the joint is staked in place and the shape of the yoke precludes fitting internal snap rings. Specialist shops can recondition the shaft for around $350.

One other thing - change the other mount. It isn't easy, but I managed it on my son's C43 with no special tools. Just put the wrench on the top bolt a lever it over with a bar. You now have the engine cocked relative to the driveshaft which is probably why it is worse.

 

That's super helpful advice, guys. I appreciate it.

Hoping to get it figured out this weekend. But I seriously hurt my arm and shoulder trying to muscle that remaining mount's bolts loose. My arm's still sore as hell today, so I'm hesitant to tear back into it again full throttle and risk needing a doctor's visit or something. I'm a big wuss, I know, I know. I once sprained my ankle changing a flat on my wife's w124.

I've read another thread on there where a guy spent months tracking down a vibration/noise that turned out to be his u-joint, which was apparently replaced without incident. I'm hoping I can have the same luck. I know a really good euro shop I can just take the shaft to to get it replaced. I can do the center support myself (I think? Does it need pressing in our out?).

And btw the car has 190,000 miles. My other C43 has 262k miles and the service history only mentions replaced flex discs. I'm confident the center support is out because of a slight vibration at 55-60mph. It's not bad, though, just annoying for now.

This issue and the roaring ac compressor pulley are the only things stopping me from driving this C43 every day.

I drove a 1994 C280 for 254k miles and it's center support died on the interstate once. Towed it to the dealer = $880!! Lesson learned.

I'm interested to know this trick you used with a lever to get that passenger side top mount bolt off. That **** is on tight. I only have enough room for a short socket and a standard 3/8" ratchet. It's a real bear.

 

At that mileage the u-joint could certainly be suspect.

You can replace the center support yourself, IF, you have the right tools for pulling the old support/bearing off. I was going to do just that when I found the u-joint bad. I was going to put a large bearing separator under the support and use some long studs to a large puller. I was going to make a tool to press the bearing back on. Thing is, when I found the u-joint bad that project stopped dead in it's tracks. The only way I noticed the "notchy" u-joint was when I separated the halves of the shaft and moved the spline back and forth (make sure you mark the shaft before splitting the halves). I sharp detent could be felt in the running position. BTW, I knew to look for this from a discussion thread that had come up on Peachparts some time ago. This is not uncommon.

Your vibration could be coming from the u-joint. My car was noticeably quieter at 60 after the rebuilt shaft was installed.

I ended up going to a local driveline specialist shop. None of the local dealers could rebuild the shaft and the local independents either didn't know what to do or they would try to find a used shaft - a crap shoot IMHO. The specialist shop does mostly commercial vehicles, but were very familiar with the issues with this repair on M-B and BMW vehicles. They could not do the repair "in-house" but had a vendor that could. The repair took only one day. The shaft came back with a new u-joint, center support and was re-balanced. When I look back on it the $350 price was quite reasonable considering what I got in return.

As for the mount bolt, being careful and not getting hurt are first priority IMO. IIRC I placed the box end of a wrench on the head of the bolt. A socket and short breaker bar might work. Just be careful and make sure you are clear if something slips.

 

Anyone know if there's a danger in running the car with the driveshaft disconnected from the transmission? I figure I can isolate the issue really quick if I can:

Unbolt and remove flex disc between transmission and drive shaft
Start car
Put in D
Blip the throttle and see if the noise/knocking is still happening.

 

I think that may sound attractive but in actuality it will be tricky. First, you will have to remove (and temporarily reinstall) the rear mount. To get the flex disc out you will have to push the front half of the driveshaft back on the splines quite a bit. There is a centering sleeve on the driveshaft that fits over the end of the output shaft. To get the flex disc through that gap is hard sometimes. Then the centering sleeve will have to be reinserted on the output shaft (it will want to drift forward anyway because the rubber bellows over the spline acts like a spring). Also, I don't know how the transmission is going to act with zero load on the output shaft. Will the noise, if it is coming from the transmission, disappear temporarily? If it were me I'd get it on a rack at the shop you mention and get a good look at it.

 

You may be able to try it. In addition to the advice already mentioned, keep this in mind, the output shaft will be spinning as soon as you shift from park. Even if you shift to neutral, the shaft will spin due to friction. Be sure to turn the engine off before pitting the transmission into park. This will save your parking pawl and ring from possible damage.