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Hey everyone, trying to find where this bolt goes on my 2014 C300 4MATIC Sport.
The other day I was doing an oil change and when I pulled the splash guard off to get to the oil pan this bolt was just sitting on it...
The bolt is an E12 Torx and is about 3 7/8" long or 98.425mm.
It's a partially threaded bolt which leads me to believe it may be related to something suspension wise but I'm not seeing anything when I look.. I've also had a "metal/shaking" sound when going over potholes or other rough bumps which would cause the suspension to quickly compress. Looks kind of similar to one of the bolts on the strut tower.
I know it's a pretty vague question and there could be tons of applications for this bolt but hoping maybe someone can help me find a way to check any spots this thing may be missing from or just any information in general.
(Head of the bolt says KX2 with the number 88 below it)
2015 SL400 (M276 Turbo), 2014 C350 Sport (M276 NA), 2004 SL500 (M113), 2004 Audi TT225 (BEA)
Can you measure the bolt diameter? The length is close enough to 100mm that the bolt size might be something like M12x100 or M10x100. As Tim mentioned, the suspension bolts I've seen are always 10.9 hardness.
Hey Tim, glad to see a reply from you considering the amount of help you gave me with my trailing arm job!
Yeah I wasn't sure about the bolt grade either. The initial measurement included the bolt head. I did re-measure and got 92mm without the head.
As far as which side was close I'm assuming you mean which side did I find the bolt on? If so, I'm not sure. When I removed the 8mm screws to drop the guard it just came rolling out.
That bolt in the diagram you mentioned looks like the threading is a bit shorter depending on how accurately it depicts the bolt. I'll crawl up under there later today and see if I can't take a look at it.
Edit:
I'll check the alternator bolt as well. That picture looks very similar to the bolt
Last edited by TheMilli; May 9, 2024 at 12:03 PM.
Reason: Got a new reply while typing initial reply
Maybe the bolt holding the alternator on. its 90mm. #200 in diagram.
I was able to run and do a quick check on the alternator. All 4 bolts are there so that's checked off the list. I'll get back about the one on the steering rack later today.
@TimC300 is close. It’s a shoulder bolt so similar application. The 88 is probably 8.8 strength. Just off the top of my head: A/C compressor, power steering pump, aux air pump. Also, some of the timing cover bolts may be long, but that would be unusual.
Its used on the alternator and also the ac compressor to hold them on.
That bolt looks clean, is that how your engine bay and car looks in general, clean? All my exposed bolts look mostly filthy.
Was anything done to the car recently, or ever that you know about? Anything that would require the alternator or the ac compressor removed?
Anyone else work on the car that could have dropped that bolt and installed another one instead because they couldnt find it?
I dont see how a bolt like that can wiggle out on its own.
Originally Posted by Odd Piggy
@TimC300 is close. It’s a shoulder bolt so similar application. The 88 is probably 8.8 strength. Just off the top of my head: A/C compressor, power steering pump, aux air pump. Also, some of the timing cover bolts may be long, but that would be unusual.
Yeah most of the bolts are pretty clean in general.
I've had the car just under 2 years now and haven't had any issues up until the beginning of this year. Since I've owned it other than putting tires on, I've done all the work myself and the only front end work I've done is control arms and brakes which don't have any bolts that match up. Previous history other than oil changes I'm not sure about.
I'll check out all the other places you guys mentioned today and get back to you.
2015 SL400 (M276 Turbo), 2014 C350 Sport (M276 NA), 2004 SL500 (M113), 2004 Audi TT225 (BEA)
The strut tower bolts are E12 and the ones I could see on the power steering pump are E12, but the two in front are blocked by a pulley and the accessory belt. Another bolt on the side of the PS pump is also E12. None of these look like they could just come out. I could not get a good view with a mirror to see what was stamped, if anything, on the head.
I'm pretty much at a loss for where that things goes at this point.
Crawled under there today and checked everything mentioned in this thread and all the bolts were there. I spent a good 30 minutes just skimming over anything this could of came out of and found nothing.
Like it was mentioned before, I'm pretty confused how a bolt like this would even make its way out of wherever it came from but for now I'm just gonna assume everything is good to go... Still not sure what that "clanking" noise is when going over pot holes and such but I'm assuming that is an unrelated issue.
I'm pretty much at a loss for where that things goes at this point.
Crawled under there today and checked everything mentioned in this thread and all the bolts were there. I spent a good 30 minutes just skimming over anything this could of came out of and found nothing.
Like it was mentioned before, I'm pretty confused how a bolt like this would even make its way out of wherever it came from but for now I'm just gonna assume everything is good to go... Still not sure what that "clanking" noise is when going over pot holes and such but I'm assuming that is an unrelated issue.
Thanks for the suggestions guys!
Do you know your sub model, as in 204.???. Or what is your vin # so i can look it up. I am very curious to find out where it goes.
I have been looking at my cars 204.081 diagrams which should be pretty much the same as yours, except yours is 2014 and mines 2010. May be some different engine related things that im not seeing with my diagrams.
I went thru the diagrams for the suspension, front axle, substructure, steering, front end/firewall, exhaust, and my M272 engine. I searched for every bolt from 80-100mm and the only ones ive come across are the alternator and the ac compressor bolts.
Which undertray was it laying on, the front or the middle one?
The starter bolts look to be hexagonal head M10x90mm. Could be different for other engines.
The 3 bolts at the top of the strut are only around 1" long. The other two bolts holding the strut to the wheel carrier are 70mm and much thicker.
When I had metal-on-metal clanking it turned out to be bad sway bar links. It was most noticeable when at highway speeds hitting a pot hole. It sounded like 3-4 clanks in a row, the first one loudest. Easy way to check sway bar links is with the entire front end in the air wheels off just grab the link and see if it twists easy, if it does the ball/socket is probably worn. Check the rubber boots for tears, water can get in and wash the grease out resulting in faster wear.
Sorry for taking so long to reply some personal stuff came up and had to leave the problem alone for a while.
The bolt has yet to find it's home. I'm convinced this doesn't even belong to my car at this point lol. As for the "clanking" noise it is still there and I've replaced a few things with no fix. So far I've replaced the lower control arm and the sway bar links on both ends.
The noise is coming from the center of the car which is why I've been lead to think the CV axle could be an issue? It seems odd to me that it would be this because I have no other symptoms of a bad CV. I'll post a video and all the symptoms I've noticed below.
Symptoms:
- Metallic "clanking" noise when going over pot holes or other rough bumps between 15 MPH and 30 MPH
- Backing up or going forward at low speeds (5 MPH or less) giving the brake a quick firm tap it almost feels like something is shifting
looking at the video, is it normal for the CV axle to have play/make noise like that? I’ve only replaced a few in my life but it’s always been for bad linkage. Everything on my CV seems to be fine other than the noise when I shake it.
Clanking and clunking over potholes is often something like a bad strut bushing, bearing, or bumper.
This was my assumption as well. I was planning on taking apart the strut and looking at it but I'll have to get a strut removal socket first.
But I also feel like if it was strut related I would notice other issues don't you think? If I go over long smooth speed bumps (the ones that are more like hills than bumps) I don't notice anything at all. The car also sits perfectly fine and I don't notice any sort of extra body roll when turning either way. Maybe it could be the bump stop but that just seems so un likely to me.
I will most likely be taking it apart soon either way just to check it out.
Im wondering if the previous owner had work done and dropped the bolt, couldnt find it, so installed another bolt? Does look like the alternator bolt to me.
The cv axle does move in and out, like in your video. Its designed like that. Unless the boots are torn and leaking grease I wouldnt think they are the cause of the noise.
Maybe jack up the front end and start wacking things with a rubber mallet, not the engine but connection points of the suspension and steering. See if you can reproduce the sound. Hit where the sway bar connects to the car.
I was just remembering over the winter I heard a banging noise that in my head i thought may be the sway bar link, to me it sounded like metal hitting metal. Turns out there was a screw missing securing a section of the plastic undertray. This section when not secured is allowed to really bang around under there. It was missing the screw and the metal insert in the frame. Worth a look to see if all the screws in your undertray are there.
What brand sway bar links did you install, Mercedes? Did you torque the nuts down to 98nm/72ft lbs?
I ask because i had previously bought and installed a set of chinese knockoff links and had issues, actually 2 sets since the first set was defective right out of the box. Returned and ended up installing a Febi set of links which were working great, until i recently noticed one of the boots is already cracking apart. Im about to exchange it under warranty.
In the oil exchanger repair work there are a couple of those screws I think I remember.
A three-bolt rear tie rod behind the steering pump sounds familiar to me.
In what area was the screw?
Im wondering if the previous owner had work done and dropped the bolt, couldnt find it, so installed another bolt? Does look like the alternator bolt to me.
The cv axle does move in and out, like in your video. Its designed like that. Unless the boots are torn and leaking grease I wouldnt think they are the cause of the noise.
Maybe jack up the front end and start wacking things with a rubber mallet, not the engine but connection points of the suspension and steering. See if you can reproduce the sound. Hit where the sway bar connects to the car.
I was just remembering over the winter I heard a banging noise that in my head i thought may be the sway bar link, to me it sounded like metal hitting metal. Turns out there was a screw missing securing a section of the plastic undertray. This section when not secured is allowed to really bang around under there. It was missing the screw and the metal insert in the frame. Worth a look to see if all the screws in your undertray are there.
Originally Posted by TimC300
What brand sway bar links did you install, Mercedes? Did you torque the nuts down to 98nm/72ft lbs?
I ask because i had previously bought and installed a set of chinese knockoff links and had issues, actually 2 sets since the first set was defective right out of the box. Returned and ended up installing a Febi set of links which were working great, until i recently noticed one of the boots is already cracking apart. Im about to exchange it under warranty.
Passenger side Febi link after only 2yrs:
I actually have all 3 under pans removed right now and still have the issue. I tried getting a video of the noise but being that it only happens between 15 mph and 30 mph it's hard to get a good clip without the sound of wind or other noises.. I'm going to replace the CV axle and see if that could be the issue. I know it's unlikely but for some reason I just feel like it's got a little more play in it than it should and the whole slow roll braking that makes it feel like the axle is slipping is the biggest reason I think it could be the problem.
The links I installed were Delphi (TC3385 and TC3384). Was going to go with MOOG but I liked how the Delphi matched the style of the OEM's.
It may be a bit until I get to it but once the axle is replaced I'll post an update! On top of all these issues I'm now getting the start up rattle from the VVT sprocket/Cam adjusters on the driver side so I guess I'll be adding that to the list of things to do
For what it's worth, I had clunking that I swear was something else other than the strut, but turned out to be exactly that. Didn't know struts clunked but they did. Probably wasn't the strut bearing since on the 204 the thrust bearing is mounted on the spring, not the strut rod, and under load even when the suspension is unloaded.
Had some time to pull the strut out yesterday and discovered that the bearing seems to be bad? I'm not exactly sure if it is or not but it has a ton of play and spins more freely than i would assume a bearing should so I'm going to replace it on Wednesday and will update.
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