ILikePeeps

Hi all, just registered. I just real recently acquired a used 2007 c230 Sport Sedan, and I've just hit 119k yesterday or so.

Anyways, I've been noticing some type of grinding sound (not real harsh, but noticeable). It seems to happen with lower speeds, as in.. ~5-30 mph or something, and perhaps with RPMs under 3k.

I'm not sure, but it may not seem to happen after the car has been driven for a while (warmed/heated up?). And I also have maybe not noticed it while driving faster such as highway speed(s). It seems to come from the front of the car under the hood or so? I don't think turning while driving has any noticeable affect to where it happens.

Ideas?

It's a slight grinding kind of sound, and it doesn't seem constant like "grrrrrrrr", but more like "grrr gr gr" (intermittent?)

jogger

is it modified?

ILikePeeps

Not that I'm aware of, and I didn't notice anything on InstaVin or w/e or being told anything from dealership. So, it may be stock with exception of maintenance stuff?

Edit: The sound might not happen while the car is in idle or parked either though, but I'm not sure about if I rev it while parked.

ILikePeeps

Listen to a recording I did, it's not as loud on the recording maybe, but..

Anyways, pay special attention at 5 or so seconds, try to listen for like a grinding noise.

http://vocaroo.com/i/s1pVpiRXwAPx

Edit: Not that whining sound, but the like grinding noise...

jkowtko

It's faint, but to me it sounds like a bearing going bad on one of the pulleys on the front of the engine.

On the serpentine belt on the front of the engine you have, in rough order of easiest or least costly to replace:

1) idler pulley
2) tensioner pulley
3) power steering pump
4) alternator
5) coolant pump
6) AC compressor

Not sure if this is from your engine, but you get the idea ...



If you are diy-minded and can get the torx bit that will let you release the tension on the tensioner pulley to remove the serpentine belt, you can try spinning some of the pulleys yourself to see if they turn smoothly or not.

But it might be easier to get in there with a screwdriver to feel the strength of the vibration when you touch it to a (non-rotating) part of each pulley mount.

I don't know if holding an iPhone or other small recording device in front of each pulley will be enough to let you figure out which one is making the noise.

====

There's also a chance of it being something in the cam/valve assembly, or loosening timing chain. I thought timing chain sounded heavier than that though, and I would expect to hear a valve tap if something was loose on top. But I'm not an expert on these things ... so to me it sounds like a bearing.

ILikePeeps

Thank you for the response jkowtko! I'm not as mechanically inclined as my Dad and brother are, and I'm certainly not mechanically inclined when it comes to MBs, hah. Perhaps good news if it's simply (a) pulley(s), rather than something more costly/major.

jkowtko

Try the screwdriver trick first. Using a long screwdriver or a long solid metal rod, touch it to a stationary part of each pulley assembly one at a time while someone revs the engine to get that sound. If you're patient enough you will hopefully be able to feel which part senses the vibration the loudest.

ILikePeeps

Thanks again, I will update in this thread perhaps sometime tomorrow (the 6th) in earlyish-mid afternoon.

ILikePeeps

Wow.. I typed up quite a bit of stuff and it didn't submit... are you kidding me..

ILikePeeps

Ugh, well maybe I'll keep this one more brief and not necessarily as accurate/non-accurate or w/e.

1. No major engine or w/e problems seemingly found.
2. CarMax had maybe paid for it to be serviced back in Jan of 2012 for $644.xx or so.
3. Title changed in Jan of 2012 as well, so perhaps it was sold by CarMax, which may be a positive thing seeing as how it was probably considered up to par to be sold by that company.
4. Might get car back tomorrow; going to get (or unless the process has already started or something?) tranny fluid stuff done as well as new filter, perhaps a better safe than sorry situation.
5. Rode with a tech or something with my Dad and I to try and help hear/point out(?) the like grinding noise, though the person may have seemed to not notice it while I did and perhaps my Dad at least during one point/part of one point. The guy mentioned about the tranny or the whining sound being louder than normal, however I don't know if that's true or what; perhaps because of stuff that has/will get done with the vehicle (fluid/filter) that it'll get better?

jkowtko

When I changed my transmission fluid it felt like it quieted down a lot ... cross your fingers ...

MagCL

Instead of using a torx, use a (17mm I think) socket or wrench to turn what looks like a nut attached to the tensioner to remove the belt. Look at my attachment, its to the lower right of the pulley. It's a little bit more secure than the little torx screw.

jkowtko

On the pulley you pictured, you are correct ... it looks like the torx bit in this tensioner is the bolt attaching the pulley.

Here is a pic of the one on my car (M271) where you can see the torx hole for releasing tension ... you may have the one pictured above which would use a standard hex socket ...



Definitely don't accidentally remove the pulley while it's under tension!

MagCL

I think that op may have the 272 engine though. I guess he will know how to loosen both tensioners now.

ILikePeeps

Got car back, no charge for diagnostic(s). Tranny fluid was drained and filled or something, as well as new filter.

Got papers in which includes stuff that passed, failed (or at least what it's considered or something?), and caution.

However, all of the failed stuff has something about being based on mileage or time, or w/e.

So, perhaps thing(s) were changed at a non-MB place, thus them having no previous record(s), thus the failed statuses? Things such as cabin air filter perhaps.

Also, which type of engine does the car have? Here's two pics that may help identify what engine type it is..

jkowtko

Sorry, I shouldn't have mentioned the torx version of the tensioner ... 2006+ C230 switched from the I4 to the V6 ... So as MagCL says you should have the M272 engine, which has the hex bolt on the belt tensioner:

http://www.partsgeek.com/catalog/200...tensioner.html

Also, you mentioned filters ... both the engine air filter and the cabin air filter should be pretty easy to change and will save on unnecessary labor costs.

By the way, is the transmission quieter now after the fluid change?

Javvy

did u use MB or equivalant fluids??

Very important any good MB indy would know about this important fact...

Javvy

ILikePeeps

Car was serviced at a MB dealership or w/e, .

MrC240

You better hope it's not a pulley and or belts. My pulley just went yesterday and they don't make the pulley itself anymore for my car so I'm paying $1000+ for a whole new AC compressor along with main serpentine belt and under pulley.

VVF

C240, check your alternator pulley. Should be freewheeling in one direction, without engaging the alternator. I would almost bet it's seized on you.