When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
It sounds suspiciously like an exhaust leak because of the very low rumble.
Check under your car and examine the entire length of the exhaust pipe, specifically at the joints. These things can and do crack as well as corrode. Not sure about your particular model but the manifolds are also known to develop cracks at the welds because MB didn't add any flex sections.
Last edited by slammer111; Feb 21, 2021 at 01:28 AM.
It sounds to me exactly like a classic exhaust leak.
It can be from the exhaust manifold, or any pipe in the exhaust system.
Open the hood, see if you hear noise near the exhaust manifold.
Get cardboard, etc, put on the ground, then listen/look for leaks under the car.
Note: The exhaust can get very hot over 300F. Use gloves/etc to protect your hands, if you're going to feel around.
Also, car jacks are NOT SAFE enough for people to get under the car.
Car jacks fall ALL THE TIME - people get injured and killed - a lot! So, do not use a car jack, then crawl under the car.
Look on the exhaust side. Start at the manifold and follow the entire length of the pipe all the way down to the muffler. Specifically check all welded sections and joint connectors, all the way around. If there is nothing there, check the rest of the piping. If still nothing, have a buddy start the car and rev the engine. That should show the source of the leak real quick. Be sure to wear safety goggles to avoid getting a blast of hot exhaust to the face.
As RedGray mentioned, do not depend on a jack to hold the car up. Jack stands or ramps only.
Last edited by slammer111; Feb 19, 2021 at 12:49 AM.
my brother and I went out and played with the car. he revved the engine up and nothing was leaking from underneath. that puddle came out of the exhaust. I took a picture of that random part hanging off. I don't know what it is or what happened to it, I also made a video of the engine bay, no leaks at all. but I did smell a fume for a short period of time before it went away. it smelled like an old fart haha. puddle from exhaust random plug hanging down
>>RedGray
>>It sounds to me exactly like a classic exhaust leak.
>random plug hanging down
Sweet, I was right. What do I win? ;-)
Good bad/news.
Yes, you have an exhaust leak.
Good News: Your exhaust pipes/mufflers look like they are in pretty good shape.
Bad News: That's an oxygen sensor. It may be the primary or secondary. Either way, it is bad that it's broken off.
Bad as in "likely not cheap to fix". You'll need at least two new oxygen sensors (primary & secondary ~$50->$100+ each). And, at least one (maybe both) new catalytic convertor and down-pipe section. Around ~~~$400-$700 each. Plus, removal, install, etc.
The leak might simply be the hole where the oxygen sensor used to sit.
Replace the sensor first. I would not reuse that one. Bouncing along the road can't be good for it.
The next question would be why the sensor fell out in the first place. Hopefully the hole/bung where the sensor sits is still attached, and has good threads.
Last edited by slammer111; Feb 23, 2021 at 02:55 AM.
Welding those bungs to the pipe/cat requires MIG/TIG and some reasonable amount of welding experience.
Plus, the oxygen bung came off the pipe/cat for a reason. It's most likely because of rust. So, trying to weld to that area would be a joke.
In the picture posted, you can see that the mounting bung is still on the oxygen sensor.
So, for whatever reason, the mounting bung came off the pipe/cat.
Adding/moving oxygen sensor bungs gets into an semi-involved topic. It's not too hard to do a half-*ssed job putting on a sensor bung, and say "Look. I fixed it, I be super smart". When, in truth, it was a POS cr*p repair that will fail is a short time. So, there are plenty of POS ricer repair/etc options, that are great for screwing the buyer. Similar to the many many exhaust sleeve clamps, and the extremely few good/acceptable ones.
The following are pictures of a different catalytic convertor. But, they show what a MB oxygen sensor bung on a catalytic convertor looks like:
(Below, the oxygen sensor bung is in the middle of the catalytic convertor.)
what tells you that it's an exhaust leak? I want to know exactly for myself. I appreciate how you broke it down in the good news/bad news. I am currently looking for oxygen sensors right now. When tackling the catalytic convertor and down-pipe section task, what should i be looking for to determine what needs to be replaced, since you said a least one or maybe both? thank you for the links.
As I mentioned above: "Welding those bungs to the pipe/cat requires MIG/TIG and some reasonable amount of welding experience.
Plus, the oxygen bung came off the pipe/cat for a reason. It's most likely because of rust. So, trying to weld to that area would be a joke."
Fwiw, I taught engineering for many years. I was initially going to be college professor. But, building real things proved to much for me to pass up.
The point is that I know very well that no one is born "knowing about stuff, or how to do stuff". Imho, that also why I think that teaching is such a neat profession - they can change people's lives for the better.
I learned about cars/etc from some great mentors. I also made a lot of mistakes, and learned a lot along the way.
My comment about never ever ever trusting a car jack - guess how I can say 100% that it may work fine many times, but all it takes is that one time, and then you better pray for the best. Fwiw, I was lucky - very lucky.
This is well past a repair for someone new.
It takes time, experience, tools, knowledge, etc.
There are many ways that someone rather new to car repair can cause massive damage when trying to replace an exhaust.
Now, I have a nice ~$600+ tool to heat bolts, to get bolts loose from a cylinder head/etc. I've also use torches/etc many times to loosen bolts. And, I've snapped many bolts because I didn't have that experience that has to be obtained in real life (nor the expensive tools, along with the experience and knowledge on how to use them).
I don't know what your local laws are for catalytic convertor replacements.
Maybe, just maybe, thanks to the past election and this PITA pandemic, people will get a better understanding of the name of this country, and what it really means - The United States of America.
So, you may be able to have a local mechanic just replace the bad catalytic convertor & down-pipe, along with the oxygen sensors.
Or, you may be screwed like the people in CA, where just about every mechanic/shop would require two new cats. And, they could also very easily require new mufflers and pipes, even those yours look in very good shape. Sigh.....
I don't know your local laws.
Again, the laws vary by State and by County. That's how it is. Being a life-long New Englander, I guess I know/appreciate the history/reasons more than most.
Instead of guessing, look at the damaged area on the exhaust system.
A video is nice, but the resolution is poor.
And, you clearly can't tell what is or isn't on the oxygen sensor, from the video or from looking.
Imho, it very strongly looks like that either the threads "stripped out", or part of the sensor bung is still on the sensor. Maybe someone replaced the sensor, and stripped/cross-threaded the sensor when the threaded it into the bung.
Or, maybe Superman had too much to drink, and went around ripping out sensors from cars.
Or, maybe Anna Kendrick is leading the smurfs on a rampage to damage exhaust systems.
Or.....
Hey, I have a great idea, look at the damaged area on the exhaust system.
What O2 sensors look like, notice the threaded area.
I have the same droning noise on my 2007 e320 diesel and I’m still trying to figure out what the solution is! So I took it for a spin last night and went through manual mode. I really pinned it down to this.. Gears 1-5 shift perfect and drove smooth as butter, when I hit 6th gear around 40mph on light throttle, the car just vibrates and shakes so bad. Even under load. It’s as if I am driving on unbalanced tires. It’s anytime it gets into 6th and 7th gear. Has anyone had that happen or know what the deal is?
I spent two weeks going back and forth between wheel bearing, ball joint, engine mounts, wheel balance, drive shaft, u joint, flex disc, differential, carrier bearing as alignment. All of which is in good shape!
I took the car to AAMCO, and they said it’s a bad transmission but couldn’t tell me what exactly was bad. So I am going for 2 more opinions... one at another transmission spot and another at an import specialist.
Help! I really want to keep the car but It’s not worth 4K to fix it.
Mercedes SLR McLaren 722 S Is Extremely Rare Example Modified by McLaren
Slideshow: A one-of-one U.S.-spec Mercedes-Benz SLR McLaren Roadster became even rarer after a factory-backed transformation at McLaren's headquarters.
