Mercedes-Benz Forum banner

1 - 20 of 20 Posts

·
Registered
Joined
·
125 Posts
Discussion Starter #1 (Edited)
lower/rear engine knock: "tocktocktocktock" (sounds expensive)

So I've got this sound. tock-tock-tock-tock. Recording attached in zip file or listen via google drive. I have pretty much had it since I bought the car with ~104kMiles. The mechanic for the PPI called it a valve lifter. It was (or felt) more intermittent than now. The mechanic said he's heard them before and to not worry about it because these engines run forever. I'm now at ~135k. It's louder. So now I'm worried about it anyway.

Dealer oil-change records from 1st owner. Oil change records from recommended MB indy from second owner. I've been doing my own 0-40 Mobile 1+ fleece changes about every 8k. Noise doesn't seem to change with fresh oil/filter.

The sound is most-likely coming from the back of the lower engine. At least if my garden-hose-to-ear test is accurate. I notice it most during the summer when the windows are open. Especially if the sound can bounce off another car or a wall or something. You don't hear it above idle, but I don't know if it goes away or just gets drowned out by the engine noise. The noise also isn't really noticeable from the front of the car with the hood up. Again, it gets drowned out by all the other accessory sounds. But from beside the car (seems equally loud on either side), it's usually pretty apparent. Sound exists in Park, Drive, Reverse, and Neutral. Slightly louder, but same tone and speed in Drive and Reverse.

Car runs well. Pretty horrible gas mileage anywhere but the freeway, but I attribute that to our traffic. The fact that it gets 23-35 with a roof rack and two standup paddleboards seems alright to me.

The phone-quality (sorry) recording was made next to drivers door, with belly pan removed (though you can hear it without the pan removed) and sound reflecting off driveway. I tried to make a recording from the front but the fan and belts and ticking of purge valve etc drowns it out. 99% sure it's not coming from serpentine belt or tensioner or injectors or anything like that. Definitely a clunk or tock vs. a tick-tick-tick.

Thoughts?
 

Attachments

·
Registered
Joined
·
1,531 Posts
I'm not sure it sounds like a lifter. Sounds a bit heavier with lifter noise in the background,but maybe that's just the recording.
I had a lifter tick tick tick at start up once,fixed it by driving for about a minute at 4000rpm,,,this increases oil pressure to the lifter and can clear a small blockage.
I also switched to 5w-30 oil,I think that helped too.
 

·
Registered
Joined
·
125 Posts
Discussion Starter #3
I'm not sure it sounds like a lifter. Sounds a bit heavier with lifter noise in the background,but maybe that's just the recording.
I had a lifter tick tick tick at start up once,fixed it by driving for about a minute at 4000rpm,,,this increases oil pressure to the lifter and can clear a small blockage.
I also switched to 5w-30 oil,I think that helped too.
Thanks for the response. I'm pretty sure it ISN'T a lifter. My brain is going to rod knock or something terrible like that (I thought these motors lasted forever?). I owned various VW flat motors. Vanagons were notorious for hydraulic valves going flat. That 4000rpm trick worked to fluff them up again. Until it didn't But by then you needed new heads anyway ;-)

Needless to say, this is not that sound. This is deeper/lower.
 

·
Registered
Joined
·
1,531 Posts
A strong dull noise that becomes more rapid as the engine speeds up indicates worn or damaged crankshaft bearings or crankshaft.
Disconnect the coil to one piston at a time and crank the engine over. If the noise stops you have found the problem area.
A similar but slightly higher pitched noise indicates rod bearing wear or damage.
Good luck.
 

·
Registered
Joined
·
125 Posts
Discussion Starter #5
How long do we have?

A strong dull noise that becomes more rapid as the engine speeds up indicates worn or damaged crankshaft bearings or crankshaft.
Disconnect the coil to one piston at a time and crank the engine over. If the noise stops you have found the problem area.
A similar but slightly higher pitched noise indicates rod bearing wear or damage.
Good luck.
Thank you. Though I'm not sure I want to definitively either of those thing that without knowing what "the next step" is. Rebuild? Engine swap? These cars are worth, what? $3000? $4000? What do either of those options cost? $3000? $4000?

Maybe a better question is: if it is bearing wear how long can it go before it grenades? And just as important: how did it happen, given the service records, in the first place?
 

·
Registered
Joined
·
1,531 Posts
very difficult to answer your latter questions.
Engine swap vs scrap vs do nothing are decisions only you can make.
 

·
Registered
Joined
·
125 Posts
Discussion Starter #7 (Edited)
very difficult to answer your latter questions.
Engine swap vs scrap vs do nothing are decisions only you can make.
Oh, I know. I'm just trying to decide if I should drive it til it dies or if there's something I can do in the meantime, or just walk away right now and selling it as a running parts car. I'm leaning toward the first one. I just did a 1000 mile trip and it ran great. 25mpg with four adult-sized passegners, camping gear, and rooftop box. tock-tock-tock the whole way ;-)

I'm more curious about what could have gone wrong throughout the car's ownership to get this "bulletproof" engine to the point where it's making this noise. Did someone skip oil changes? Use the wrong oil or filter? Run it low on oil? Bad day in the factory? Or just bad luck.

I know I can't fix this stuff from the past, but I can't help wondering....
 

·
Outstanding Contributor , SDS Guru
Joined
·
3,240 Posts
Yes, that sounds familiar. Lifter tick, allright. I had a C240 that was sitting for about 8 months or so, same M112 engine as yours. After I fixed the issues that prevented it from starting, when it started it made that noise.

Revving the engine to 3000 rpm for a minute or two made it so that the oil pressure went up and unblocked whatever clog that was clogging the oil feed line, and the ticking went away.

So you either have a low oil pressure(doubtful), no oil going to lifter (blocked oil passage), or damaged hydraulic lifter.

Before you do oil change, do a couple italian tune ups on that car, if possible. If you can't due to circumstances, just downshift to 2nd gear and run it for at least 15 mins or so on the freeway. 2nd gear is good until 65 mph, so.... Ideally you want to be around 4000-5500 rpm for that long.

And then change oil, see what happens.
 

·
Registered
Joined
·
125 Posts
Discussion Starter #9
Yes, that sounds familiar. Lifter tick, allright. I had a C240 that was sitting for about 8 months or so, same M112 engine as yours. After I fixed the issues that prevented it from starting, when it started it made that noise.

Revving the engine to 3000 rpm for a minute or two made it so that the oil pressure went up and unblocked whatever clog that was clogging the oil feed line, and the ticking went away.

So you either have a low oil pressure(doubtful), no oil going to lifter (blocked oil passage), or damaged hydraulic lifter.

Before you do oil change, do a couple italian tune ups on that car, if possible. If you can't due to circumstances, just downshift to 2nd gear and run it for at least 15 mins or so on the freeway. 2nd gear is good until 65 mph, so.... Ideally you want to be around 4000-5500 rpm for that long.

And then change oil, see what happens.
Thanks. I'll give the Italian Tune up + oil change (plus seafoam?) a try next month when the kids are back in school and I have a clear weekend.

Interestingly, I just found this thread another motor with the same sound over in the C209 section. . The initial video/subject of the post isn't quite the same sound as mine. But someone's later post (with a file you have to download from Dropbox. Scratch that, I just put that file on Google Drive: https://drive.google.com/open?id=0B4aT_tPovn5ASDFhWWxmeG4zdXc), sounds pretty much exactly like my car.
 

·
Registered
Joined
·
162 Posts
Thanks. I'll give the Italian Tune up + oil change (plus seafoam?) a try next month when the kids are back in school and I have a clear weekend.

Interestingly, I just found this thread another motor with the same sound over in the C209 section. . The initial video/subject of the post isn't quite the same sound as mine. But someone's later post (with a file you have to download from Dropbox. Scratch that, I just put that file on Google Drive: https://drive.google.com/open?id=0B4aT_tPovn5ASDFhWWxmeG4zdXc), sounds pretty much exactly like my car.
Hello everyone,

So I am this "someone" who has the engine with the exact sound.

My threads on this can be found here:

https://mbworld.org/forums/clk-class-w209/634231-m112-engine-knocking-sound.html

and

http://www.benzworld.org/forums/c209-a209-clk-class/2865362-m112-high-rpm-wobble-noise.html


After reading all your inputs last night, but not being able to reply just yet. I ran the car for like 5-10 minutes on the highway with 3rd gear and with the RPM in the 4000-5500 range. I'll report back on any results today as I'll be able to be somewhere quiet where I can carefully listen to the engine, but please keep in mind that the second thread I linked above is about a coarse engine sound I am getting at higher RPMs and which I am not sure if it's related to the lifter tock sound you can hear in the first thread.

Thanks.
 

·
Registered
Joined
·
257 Posts
Of all the sound clip I heard you's clip sound most like mine. When does it happen??

Of all the sound clip I heard your's clip sound most like mine. When doe the ticking most noticeable. Mine is when the engine is cold but seem to go away (or greatly reduce) when it the engine get to 80deg C) almost like a switch.

If anyone can chime in on my situation that would be great. I am hoping it could be one of many solenoids. And someone suggested it can be a exhaust system since it is so temperature related. Got to get it check out but I can't get my hood open (but that is another story).
 

·
Registered
Joined
·
162 Posts
So after using a mechanic's stethoscope, the lifter/tock tock sound is coming from here:




Any suggestions as what to do next? Just remove the valve covers and start changing parts?
 

·
Registered
Joined
·
125 Posts
Discussion Starter #13
Of all the sound clip I heard your's clip sound most like mine. When doe the ticking most noticeable. Mine is when the engine is cold but seem to go away (or greatly reduce) when it the engine get to 80deg C) almost like a switch.

If anyone can chime in on my situation that would be great. I am hoping it could be one of many solenoids. And someone suggested it can be a exhaust system since it is so temperature related. Got to get it check out but I can't get my hood open (but that is another story).
Mine is pretty much all the time. Sound begins right after start. I only hear it at idle or slightly above when the car is stopped. Sometimes it comes and goes but warm or cold .... fresh oil change or not, it doesn't seem to matter. Tone may change at bit when above 80, but that's just from memory (I'm not with the car this week).

So after using a mechanic's stethoscope, the lifter/tock tock sound is coming from here:


Interesting. When I'm in the same location as the car again I'll try listening there. I don't have a stethoscope but I tried a super long screw driver and also a section of tubing -- both of which have served me well in the past -- and couldn't find anything conclusive there. To my ears it sounded lower on the engine, but the access is so bad down there without the car being on a lift, that it could just be sound radiating to the ground. I'll get a stethoscope, too.

Any suggestions as what to do next? Just remove the valve covers and start changing parts?
Generally I've had pretty poor luck with that tactic. But, assuming time and ability, popping the valve covers and having a look might turn up something interesting (or help you rule something out).

Again, once I have access to the car and a few hours to get under the hood, I'll join you all in your investigations. Thanks for joining in on this thread!
 

·
Registered
Joined
·
162 Posts
Generally I've had pretty poor luck with that tactic. But, assuming time and ability, popping the valve covers and having a look might turn up something interesting (or help you rule something out).

Again, once I have access to the car and a few hours to get under the hood, I'll join you all in your investigations. Thanks for joining in on this thread![/QUOTE]

Thanks for chiming in.

I read in a lot of thread that those who changed the lifters and/or crankshaft were still left with the sound and it was very frustrating to them. Most conclusions point to "just leave it alone". No harm done by the sound.

In all cases, let's see what you uncover and keep exchanging info.

I found these pictures on my phone from May 2016 when my mechanic was changing the valve cover gaskets. This was before the sound started coming out which is as of Summer 2016. Maybe you can spot something in the pics below. I bought the car with 100,000 km on the clock in September 2014 and have been changing oil every 6,000 km with 229.5 oils and fleece filter.



 

·
Registered
Joined
·
1,531 Posts
Just my opinion,but looking at the photos there are some small lumps of sludge visible.
This could be the cause,blocking an oil passage to the lifter.
Looks like it has gone too long without an oil change at some time in the past.
 

·
Registered
Joined
·
162 Posts
Just my opinion,but looking at the photos there are some small lumps of sludge visible.
This could be the cause,blocking an oil passage to the lifter.
Looks like it has gone too long without an oil change at some time in the past.
Yeah following these pictures, my mechanic cleaned all the sludge and we added WURTH engine oil cleaner and changed the oil after that to flush everything out. It's been on a 6,000 km oil change cycle since then so maybe not all the sludge was cleaned back then and that's what's causing the lifter sound?

The engine also has a coarse noise when driving and revving high. You can hear it here: http://www.benzworld.org/forums/c209-a209-clk-class/2865362-m112-high-rpm-wobble-noise.html#post16397042
 

·
Registered
Joined
·
494 Posts
Not an expert, but to me that (http://www.benzworld.org/forums/c209...l#post16397042) doesn't sound very good, esp. in conjunction with the sound recording you posted earlier.

It might make sense, in your case, to have an oil analysis done before your next oil change. The company "Blackstone" is often mentioned, and they offer this service for something like 20 or 30 dollars. If there was indeed something wrong with the engine internals, it should show higher-than-normal values for wear metals.
 

·
Registered
Joined
·
162 Posts
Not an expert, but to me that (http://www.benzworld.org/forums/c209...l#post16397042) doesn't sound very good, esp. in conjunction with the sound recording you posted earlier.

It might make sense, in your case, to have an oil analysis done before your next oil change. The company "Blackstone" is often mentioned, and they offer this service for something like 20 or 30 dollars. If there was indeed something wrong with the engine internals, it should show higher-than-normal values for wear metals.
Thank you for listening to the sound and for your insight. The thing is that I no longer live in North America and such oil analysis services are not available here.

What's intriguing is that the lifter sound has been on for a year now and the high rpm coarse sound for at least 9 months and the car still runs well with no hit in the fuel consumption.
 

·
Registered
Joined
·
494 Posts
OK, I saw that I didn't pay close enough attention and mixed you up with the thread starter. So the deeper toc-toc-toc sound, then, is not from your engine. In that case I would wonder if the sound you can hear while driving might not come from another source. Could it be exhaust related? Or perhaps come from the rear differential?

Regarding the valve train noises, then, I would not be too worried and simply wait and see how it evolves with further oil changes. The little bit of sludge you had earlier did not look remarkable. A defective lifter could be replaced if needed.
 

·
Registered
Joined
·
162 Posts
OK, I saw that I didn't pay close enough attention and mixed you up with the thread starter. So the deeper toc-toc-toc sound, then, is not from your engine. In that case I would wonder if the sound you can hear while driving might not come from another source. Could it be exhaust related? Or perhaps come from the rear differential?
I assume you mean the high RPM sound here. My dad, who used to be a mechanic and who was sitting in the passenger seat, said the same thing as you regarding the sound being exhaust related and coming from underneath his feet. He said there could be a leak somewhere, but I'm having a hard time believing that since I changed both the primary cats last year. I doubt it's the differential because I can feel the sound in the front. I had changed the differential fluid 2 years ago with MB fluid by the way.

I am going to look into the exhaust on that one.

Regarding the valve train noises, then, I would not be too worried and simply wait and see how it evolves with further oil changes. The little bit of sludge you had earlier did not look remarkable. A defective lifter could be replaced if needed.
I've been using 229.5 5W-40 oils for the past two years, but the last oil change I went with 5W-30 just to see if it'll make a difference with the sound, but nothing changed. My next oil change, I am going to go with 10W-40 and see if that makes a difference.
 
1 - 20 of 20 Posts
Top