I have a 2003 W203 C230 Kompressor (built in 12/2002) with the M271 engine with 137,000 miles. My issue is not something I think is major, but it does leave me scratching my head sometimes and I just want to be certain it is not an indication of a bigger problem. Just a quick note, I have searched the forums and haven't found anything related to my issue. Upon driving the car after it sits for a long period of time, overnight for example, it has a moderately noticeable knocking sound under acceleration. There is no apparent performance loss and it starts up just fine and idles down as it should from a cold start. I will say this knocking was much more noticeable, louder, and rougher sounding over the winter months when it got well below freezing most nights. That being said, the engine is quite smooth at idle speed, even when it's in gear sitting at a red light. It occasionally shudders slightly if the engine has only being running for a couple minutes and it's not at operating temp (90ºC or so). That's the other thing, this knocking under acceleration still occurs well after the engine totally warms up, again this was more pronounced during the colder months. It only totally goes away after diving it at highway speeds for at least 20-30 mins.

Some recent history of the car (may or may not have anything to do with the issue): about 7,000 miles ago, the whole engine wire harness was replaced by the stealer along with 4 new spark plugs and 2 new oxygen sensors. (Oil had wicked from the leaking cam sensors all the way to the oxygen sensors which caused big problems and a lot of trouble...) Prior to that, the cam sensor "pig tails" and actual sensors were replaced under recall. However, upon recently removing the plugs from the sensors, the connectors are totally saturated with oil. I'm thinking maybe the sensors themselves weren't actually replaced

Anyhow, after getting the new harness on, I am getting excellent gas milage. I can easily get 30 mpg cruising at 80 mph on the highway and typically get around 22-23 mpg in the city (I would consider myself a spirited driver ). I have always used 93 octane fuel from the same station (which says is ethanol free) and use a bottle of Techron every few thousand miles and run it hard every now and then as I have heard many people say you should not baby the M271 . I try not to drive it like a race car all the time though.

So my current thoughts are that it could be the leaky cam sensors sending erroneous data to the ECU that is causing the timing to be slightly off when it's cold. Could this be an early sign that my timing chain is starting to stretch? Also, could the motor mounts cause a knocking noise like that? I think they are original... I'm kinda stumped other than that.

Any thoughts or tips would be appreciated. Thanks in advance!

 

One thing I forgot to mention is that there are no stored or pending trouble codes.

 

Timing chain!! Search for the m271 timing chain stretching noise and see if it sounds like that.

 

Here's a video of my car starting up several months ago back before the harness was replaced and it was running very rough. One other thing to note was that my belt tensioner recently seized and was replaced, so some of the noise here could be coming from the failing tensioner.

I couldn't find any go videos of the chain stretch noise, only videos of the chain itself with the cover removed. I will try to get a new video of the start up in the morning.

 

Here's a video of the engine cold starting early this afternoon before I went to work. It had been sitting for about 20 hours or so. Tell me if this sounds good or bad! The cold start has sounded pretty much the same way since I got it nearly 3 years ago with 90,000 miles. Also, the serpentine belt, idler pulley, and belt tensioner were all just replaced about 1,000 miles ago so I highly doubt there is any noise coming from any of those.

I would like to do a visual inspection of the chain, but I have been so busy that I haven't had much time to research, let alone physically take off the valve cover. I would imagine it shouldn't be too difficult to do. Is there a thread that has steps (preferably with pictures) on how to do this? I haven't come across any yet. Thanks!

 

Yeah man, that sounds like your timing chain.

 

How soon do you think it should be changed? Like tomorrow or in the next few months?

 

Yesterday!

 

I just got finished reading through Hogger's thread on his timing chain and head adventures. I watched/listened to the cold start videos posted on page 10 and 11. It seems that most of the engines I've heard make all the same noise at start up, mine included. Any one else want to chime in?

I've thought about taking it to my indy to get his opinion on the matter and check to see if the chain is stretched. I don't have the time or the tools to change it myself so I figure I'll just take his advice.

 

Most mechanics will hear "chain" and insist to you that it does not ever need replaced. I've owned an M271 car, though I don't anymore. I loved my 2005 C230 but the chain was the reason I ended up parting ways with it. It had 146k miles.

Replace that thing ASAP. If it jumps time, it will end up costing you a significant portion of the value of the car at this point to fix it. It's just not worth the risk.

 

Yeah I would like to have it replaced very soon. Any rough estimate on how much this job will cost total (labor and parts)?

 

The parts are not expensive if you source them yourself. The labor varies wildly depending on who you use, so it would be impossible for me to guess that.

 

Yeah I understand about the labor cost. I'll give my mechanic a call this coming week.

So I need to have both the chain and tensioner replaced or just the chain?

 

I would do chain, tensioner, and guides.

 

^+1
Get it done asap as it could break tomorrow or in a year but it will break eventually and it will cost you!!

BTW love Greenville I proposed January 2013 to my GF under the curved bridge at falls park in downtown then went to Larkin's on the River for dinner and spent the night at the Westin. Then the next morning went on a BMW factory tour lol I think I have my priorities in order! The only reason we stopped in Greenville on the way to Atlanta was to spend the night and go to BMW factory then all the other stuff just happened lol

 

Any recommendations on what type/brand of parts I should be looking for or where I should buy them? I know there is a brand of chain that is the OEM brand for MB, but I can't remember the name of it.

Also, after researching more in the issue, I've seen some people say all you really need to replace is the chain only. I hear the tensioner is difficult to get to, therefore it's probably a lot more for labor.

 

Alex, you might be interested in reading my thread below:

https://mbworld.org/forums/c-class-w...limp-mode.html

It's currently in the shop, likely due to timing chain failure.

About 9 months back, I was concerned about the startup noise, and posted in this thread. There are some youtubes I included of my startup sound:

https://mbworld.org/forums/c-class-w...ll-sudden.html


Also, Hogger has a great thread he started with the issues he experienced with his car. Trust me....you don't want to ignore this problem.

Cintoman

 

I just talked to my indy mechanic and he highly advised not to replace the chain or tensioner because it is very expensive and because most of the time you cannot get the timing back the way it was before. He said that in order to replace the tensioner, you have to pull the engine out and take the whole front end off. I also talked to the guy who works on my brother's Beamer who does some Benz work and he said he would check the tensioner before the chain. Is there a way to check the tensioner or is checking slack in the chain the only way?

I would really like to pull off the valve cover just to see, but I'm not exactly sure how to go about doing that. Is it as simple as taking the coil packs off, unplugging some vacuum lines, and taking off what appears to be 11 bolts?

I have read through Hogger's thread before. I'll probably read over it again sometime soon.

 

I'm in a similar boat as you, with the only difference is that my car suffered the failure. So my boat has sunk while yours is still afloat. I was looking to take the valve cover also and check out the chain, but at that point, I felt it might be a bit over my head. I too read Hogger's post, and it's very informative. And, given that I was just provided a quote of about 6 grand for a new used engine including labor to swap my engine out, or over 7 grand to rebuild my engine, my thinking is that I'm going to tackle this job myself. I'm looking at likely a jumped chain and bent valves.

In looking at the valve cover, I counted 12 inverse torx bolts. Perhaps we could tackle the jobs together, if anything. No way in high hell I'm paying that kind of money for an engine swap or an engine rebuild. And this is coming from an Indy shop.

Cintoman

 

Please listen to these guys. Pulling a new chain & replacing the use once tensioner element is easy. That's all that's required.

WIS method is in the Wiki.

This is a simple process. If the chain jumps then it becomes complex & expensive.

You ignore chain noise at your peril with the M271.

 

Clintoman,

Yes, I read through your thread and it certainly seems your boat has sadly sunk. While my boat is still floating, I do believe that I may be beginning to take on water

I will be off of work tomorrow by 2pm, so I will probably have time tomorrow afternoon to pull my valve cover, once the engine cools of course. I'm almost certain of what I'm going to find; a stretched or loose timing chain. I guess the only good this will do me is actual visual confirmation. I've been thinking about contacting the Indy that works on my brother's Beamer again because when I talked to him this afternoon, he seemed a lot more willing to help me out. Just out of curiosity, I suppose it wouldn't hurt for me to call again and ask for his quote to complete this job.

My biggest fear in doing the chain swap myself is not installing the chain properly or throwing off the timing. I also don't have the tool to link the ends of the new chain together, so there's another expense. The biggest task I've ever done on my car, or any car for that matter, is changing and flushing the coolant and power steering fluid! In other words, I don;t want to bit off more than I can chew with swapping the chain.

Is there any actual written DIY on this at all? I've read through almost all of Hogger's thread and while there is a ton of info, there's no pictures or anything like that to walk me (or us) through the procedure.

 

Glyn,

Could you post a link to the Wiki? Being the Newby I am, I'm not totally sure what the Wiki is

I do appreciate everyone's help and support!

 

Just as well you pointed this out. The link is gone from the Wiki. I will repair.

Here:

 

Clintoman (and others),

I am taking my valve cover off this afternoon to investigate. I will take pictures and post them. Once I confirm the chain is loose, I am going to contact the other Indy I talked about and get a labor quote from him

 

If the indy says you have to pull the engine out or anything rediculous...then I would run...run far far away from him cause he does not know what he is talking about.

Paitence is the key...you are still ahead of the game.

Goodluck.

Javvy