Rough Grinding Noise

[Daniel Rozwood]

Hi,

First time poster. Right up front, I want to thank anyone who replies. I’ve been stumped on this issue for a while. I’m about at my wits end and my next stop might be to take the car to the dealer! Also, sorry this got so long. I guess I really included a lot and tried to be detailed to help anyone reading this.

The short:
Heard noise like bearing.
Replaced bearing, passenger front coil on strut, replace cv axle – then put original back on after rebooting it
Bearing WAS actually bad.
Car still makes noise (kind of a cross between bad bearing and gear grinding when you use a manual transmission and miss a gear)
Not sure what else it could be.

The car:
2006 Mercedes Benz E350 wagon. The car is a US car and we live in Western New York area (thanks for the hint about mentioning all the details “new members read this post to get the best help”). It is a 4-matic (basically real-time AWD engage but drives RWD most of the time). This car does have CV Joints on the front.

Symptoms:
When turning left at a “reasonable” speed or while accelerating (such as entering a main road from a driveway) the car makes a metallic grinding noise. The noise “seems” to come from the front passenger side of the car.

Troubleshooting (the long):
I’ve heard similar noises before on my truck – which had a bearing issue. I thought it could be the bearing. I jacked the car up played with the tire. It did not have any noticeable issues. So, having had a CV Axle issue on a ’97 Plymouth Neon, I thought it could be that. I took the car to an ex- mechanic friend. We put the car up on ramps and took a look. The CV Axle boots looked good but my friend noticed something that the dealer had not noticed in the 4 times the car had been there (inspections, or other MISC things that I did not have time to deal with). The front passenger (left?) side coil spring was snapped!

At this point, I decided that it won’t hurt to just replace EVERYTHING – if I do it myself it will be cheaper and I enjoy working on cars when I have the time.
I ordered the parts online (try to find an aftermarket CV axle for a Mercedes…I dare you!). Everything consists of the spring, the cv axle and the wheel bearing. I did locate 1 manufacturer of a CV axle for this model of car. I ordered that and all three parts arrived. My friend came to my house after work and we started to work on the car. I apologize that I am going to use incorrect terms here – I am not a mechanic, nor technician. We got the support arm off that contained the bearing. I took that to someone with a press to get the new bearing installed. The old one made grinding noises – a credit to Eric’s videos. I was certain it was NOT the bearing since there was no wobble. Following his page on noises helped get me to this point. I thought success!
However, we were not going to take any chances. After getting the new coil put onto the McPherson strut, we managed to pop the old CV axle off and install the new one. After putting the entire assembly back together, we tested the car. It now made a greater metallic sound. When we got the car back up on jacks, we saw that the new CV axle was rubbing the sub frame.

After calling the manufacturer and supplier of the CV Axle, they told me that the axle was made to fit MANY models and there was a chance it did not work with this EXACT configuration, but I had the correct part number. They “allowed” me to return the part less a restock fee. Which made no sense since the part did not fit and even so, there was no way they were going to restock this thing as it was all scratched and beaten up from rubbing on the frame.

I decided to get the original axle inspected. I found a GREAT local mechanic that only does select work because he “got sick of doing oil changes”. This was now a bit out of my reach / capability. Luckily he took pity on me! Anyway, teaching me about the axle as it was disassembled, he determined that the original axle was just fine. So, I ordered a re-boot kit for the original cv axle. He re-packed everything and re-installed the axle for me.

I asked him that IF he still heard the noise could he track it down and let me know what he finds. Of course paying for his time. He determined that he had no idea what the noise was. He did tell me that when he was pulling the cv axle that I was returning OFF the car, he saw that the motor mount was loose. He told me he found that since the mount was in the way of getting a pry bar behind the cv axle and he tried to remove it. Instead of coming out, it spun free.

Throughout this entire process, I was never able to see any scratched metal / worn or ground frame/parts/etc.

Where I am at now:
*The noise sounds kind of like a sound between a bearing grinding and when you are partially in a gear with a manual transmission, but you let out he clutch.
*Excuse my ignorance of motor mounts, but without asking the question, I will always wonder, could my problem be the bolt or something with the motor mount? Maybe when the car is listing to the RIGHT because I am making a LEFT turn and accelerating something pushes DOWN enough to grind? Something I have not been able to see?
*One friend told me it could even be something in the back of the car. That sounds can sometimes traverse the frame and “appear” to come from somewhere else, especially in a car like a Mercedes where there is about 1″ of sound dampening foam all over the bottom of the car.
*I’m a bit stuck on what to even check next.
*I’m okay taking it to the dealer – I have no fear that the car will lose value once they “mark” that the car has some big issue as a trade-in. The car was in an accident where the rear quarter panel was crumpled. Although that was all replaced the car will never be worth more than the loan – so at this point, since my wife uses it to drive our kids to school every day – would like to know what is going on and why there is a noise I’ve never heard before. I would just send her in my car – but she can’t drive stick. And you know how married people are…she can hear me teach her, but she can’t listen to me teach her.

Thank you for all of you help. I tried to include everything, I am sorry this got so long.

Topic

[Tom]

You know the motor mount is bad. It may, or may not have anything to do with the problem at hand, but I would go ahead and take care of that.

Is it possible that it IS a bearing, but not the wheel bearing? Perhaps you are hearing a bearing in the transmission beginning to fail?

[Bill]

Make sure the inner and outer CV joints were replaced. The noise deadener is right… so check all 4 wheels for play. I used to own a Porsche and changed out CV joints regularly. Are you sure the frame was not bent when it was in the wreck crumpling the rear quarter panel? Definitely go ahead and replace the motor mount. It really bothers me that that coil spring was broken… this can also put undue pressure on the opposite side of the car, involving axels, etc. Your best bet for that axle is to go to the dealer or find that EXACT model to take one off of.

[Daniel Rozwood]

Thank you both for your replies!

Tomh, thank you for the reply. Is there a good way to check that it is something IN the transmission? Or do you believe this is beyond the scope of a DIY backyard mechanic? Even the motor mounts “sound” easy, but I feel could be a bit beyond me (I’ve never supported the engine and worked on the vehicle…but you can’t learn without being in the water!).

I’ve read online to check the motor mount, put the car in drive, hold the brake and watch the motor’s movement when pressing the accelerator. Then test again with the transmission in reverse. With the hood open I should be able to see the engine move around. Also, I understand that this car has oil filled motor mounts, so checking on top of the dirt shield would be a good indicator (as whatever oil is in there will be all over) that.

Olnir, thank you as well for the reply. I will have to learn more about the CV joints. When we replace the axle, it was from the front transmission (?) all the way to the wheel. There were two movable joints. When we put the original CV Axle back in, the reboot kit had replacement boots and grease BOTH joints. Maybe I am misunderstanding? I want to be clear and check the correct things.

*We were told the frame was OK. I do believe it because it happened where the car was at a light. At change, it was being driven straight and a person on the right side of the car turned left and “slowly” pushed into the car. Not sure how else to describe it, but it did appear to be just the rear panel that was bent in. Can I say for certain? No, but I do believe the collision shop on that one.

Good idea about looking for a used axle. The OEM is the ONLY one out there and it is up in the “might as well just pay the dealer to fix it” price range (meaning labor end up nothing by comparison to the cost).

Here is what I am thinking I will do:
*Check all 4 wheels for play
*check to see about the motor mounts (look for oil, rev the motor)
*see if I can find some online information / talk to my mechanic friend to see about replacing the motor mounts (some searching leads me to think I need to do at least the pair, but good to do all three if I can)
-They seem reasonably cheap to buy…$60-80 each from RockAuto, so might be worth a try to fix this

After that, I guess I’ll reassess unless someone has any further advice. Again, thank you all for not only reading, but replying! This is certainly a dilly of a pickle!

[EricTheCarGuy]

I cover how to diagnose and solve issues like this here.

http://www.ericthecarguy.com/faq/diagnosing-noises-in-your-car

I’d be looking at the splash shields on the front brakes for starters.

Good luck and please keep us posted on what you find.

[Daniel Rozwood]

Eric,

Thanks! That was the first link that lead me down this path! Your videos have been invaluable to me. Generally, I get the right “terms” from my father (he was an A-Mechanic working on various public transportation throughout his career). Once I get the right term and his description, I watch a video online or read a tutorial. That generally gets me into a comfort area. When that doesn’t work, I bring in a friend (the one I mentioned in my first post).

So far, I have been trying to fix an alignment pin on my tractor – so I’ve not been able to mess with her car yet. I only intended to swap to my snow blade…and ended up changing the transaxle drive belt, 3 “bad” tensioning pulleys and am right now trying to re-weld an alignment pin for the PTO. When it rains, it pours…

After that, I’ll be pulling my wife’s car into the garage to see what else I can figure out. The community has been fantastic!
I will certainly post back once I have something to report. I am REALLY hoping we can work this out!

Thanks again!

[Bill]

You understand right…

[Daniel Rozwood]

I looked into doing the engine mounts myself. $80 each. Not too bad. I then looked into the process. I did not find any really good videos…or at least good for me, that made me comfortable with trying this myself.

Took it to the dealer. I know, I know, kind of a cop-out, but I did not feel comfortable having the engine suspended over my head while I “experimented” with trying to get them in.

Anyway, the dealer came back to me and apparently this resolved the issue. I spoke with the technician. He told me that the boot the CV axle has on it is a high performance material – not a typical rubber. Because of that, it was not ripping through, but just getting malformed / sandwiched between the CV Axle and the frame. With the shape of the CV Axle being a triangular shape, we would get a metallic grind, yet see no evidence of the action.

I was also mislead by YouTube information. I looked up E350 engine mounts. Apparently the online videos that showed an engine with a bad mount will rotate in the engine bay almost 3-4″ is not true of the 2006 E350. These “older” models were NOT oil filled – so they did not GIVE as much as the “blown” newer models. So, with those pieces of information, I was almost lead on a wild goose hunt not being able to locate the issue.

After relaying information about the bearing being bad…I was also warned that on this model the [I am paraphrasing] race and the bearings will sound gritty when the spindle is taken out due to HOW it is manufactured. Once you take it out, there is a good chance that it will be destroyed on purpose so that you are FORCED to put a new one in. Again, think high performance vehicle – no room for error type of thing. Same with the brakes (which I found on my car as well). They are DESIGNED to wear with a LIP on the rotor – so when replacing you ruin the pads, so you MUST replace both in order to ensure proper working order with NEW parts. Lessons learned.

Probably a video in there regarding making certain for information one gathers online is for your SPECIFIC model of vehicle. I thought my mounts were FINE because the engine did not rotate 3-4″ as it did in the video on YouTube. Nor did I see OIL all over the place as in the same YouTube video. However that WAS a newer model….and I never considered that something like an Engine mount would be that drastically different.

Anyway, thank you to the community for all the help! We should be getting the car back today after the dealer reboots the CV Axle (this annoys me more since I already did it once!).

[Author]

Replies