Initial startup whine was still there, and a very low level whine at idle. Nothing like now though. Character of the noise prior to recently was also a bit different. More chattery.

Water pump and thermostat were replaced first and made a very noticeable difference in noise levels. Bearing on the water pump was going bad and making noise. During that job I found that the double idler pulley was also bad, so I got a set of bullet pulleys from VRP and replaced them, and was extremely happy with the noise levels for a couple months. Then this noise came in about a month ago and steadily increased in intensity until the day i had it on the rack last week when it really started to get louder.

 

That is odd. The only thing that I could imagine here is the changed load due to fresh parts but sounds a thin theory and takes away the cavitation theory.

 

I think the two noises are unrelated. The noise that was formerly present was caused by worn out bearings in the pulley system and water pump. Those noises are gone now. This new noise is different and is coming from the oil pan area, likely caused by the oil pump system, and potentially a result of cavitation.

Just a note, but I drove the car for the first time in about a week this morning. The noise is significantly louder now. Loud enough that it turned the heads of pedestrians on the street as I made my way through my little sleepy German village this morning. Normally the car is a sleeper that gets little notice. It's been parked for about a week due to a leak in the Airmatic system

 

Okay, so it does appear that this noise was caused by an issue with the O-ring in the oil pump. The reason I say this, is because I just spent about 8 hours over the past 2 days replacing the O-ring, and the before and after difference in the sound is pretty drastic. It went from loud enough to distract pedestrians as I drove past, to no longer audible from inside the cabin. I'll attach a before and after video to this post so you can see for yourself, though the video isn't perfect. I should have done a "before" video right before starting on the job, because it had actually gotten noticeably louder over the couple weeks since this was originally recorded. I also wasn't quite perfect with microphone placement being equal.

The job itself is quite a bit of work, and not for the faint of heart. By the time you have everything out, you will have around 50 screws/nuts and bolts of various sizes and types to keep track of for reinstallation. I would recommend some sort of organization tools to keep track of everything. I personally laid them all out on a table in a specific way, but I started to run out of room. It would be especially difficult if you don't have access to a lift. I did, and it was still a pain in the ***. The biggest chunk of your time will be spent in removing the two sections of the oil pan and then cleaning them up. That took a solid 3 hours or so in total, and I was using a cordless drill and wire wheel. By hand with a razor blade, it would likely take you a full day.

I also took the opportunity to replace my engine mounts since it was easy, and I am glad I did. The driver's side mount was bad, even though it looked okay. It was really floppy while still bolted to the carrier, and when I put it down on the table the fluid started oozing out. Yuck.

I also replaced the Airmatic with BC Racing Coils last week, and I am happy with the results so far, though the job itself and especially adjusting the rear ride height suck ***. Still need to do a little tweaking before I am confident enough to reinstall the rear hatch interior panels, but it is already an improvement over Airmatic. Replacing the engine mounts made me even more happy with them, as there was apparently a secondary vibration from the engine moving that is now gone, so the ride feels smoother now.

Anyway, here is the link to the before and after video. If anyone has any questions let me know. Bottom line for me is that I am glad I did it, and feel it was worth the effort. If your car isn't making the kind of noise mine was, I think you might be able to wait though.

 

Thanks for posting a follow-up. To make sure we are comparing apples to apples, what type of oil did you use after the repair; was it the same weight and type as the "noisy" oil, and if so, how many miles were on the noisy oil. Time may tell if the noise returns.
Did you remove any rod caps to check the bearings for oil starvation?

 

It's the same oil, Mobil 1 Full synthetic 0W40 "European Car", and in both cases the videos were taken within minutes of an oil change. Old oil only had maybe 100 Km max on it in the past couple weeks. Would like to get Liquimoly, but it's crazy expensive here in Germany(22 Euro per liter) due to taxes and the only way I have found to get it from the States involves shipping it on a literal slow boat as they don't want to airmail flammable liquids. That takes 6-8 weeks.

I didn't pull any of the Rod caps, as I am not completely comfortable going that deep and likely wouldn't know what exactly I am looking at unless things looked really bad. Nothing seemed out of the ordinary from a visual inspection, but I am no master mechanic. I don't personally believe the engine was truly oil-starved yet, but the newness of the noise and the sheer loudness had me really worried. The car literally sounded like a dump truck or the like. I suspect it was at a stage shortly before real problems would occur, but I don't have any way to verify that to my knowledge.

On the drive home, the car felt smoother than it has lately, but I believe that was likely down to the bad engine mount being replaced. I was also less hesitant to rev it due to the knowledge that the oil supply is secure.

The fitment of the joint where the O-ring goes in my particular car may have been an issue. The O-ring was not under any pressure at all when it comes to the raised ring on the pipe pushing the O-ring down into the socket. The gap between these two was larger than the O-Ring's thickness by at least a millimeter or two. The original O-ring was very hard, and the seal it had with the pipe was negligible. It was visibly indented only on the sides touching the pipe itself, and the bore it fits in. The sides that would be pressed against the body of the pump and the raised ring on the pipe were bulged out round, indicating there was no pressure on the O-ring in that direction. The pipe fell right out of the joint as I was removing the Oil pump, and putting it back in place took no effort at all, nor would it hold on it's own really at all. New O-ring created a much tighter seal, making it somewhat difficult to insert the pipe into the pump, especially as it is all slick with oil.

I suspect it was cavitating some air bubbles around the O-ring, but that's just a suspicion. Can't think of any other reason the noise would be eliminated like that.

 

Nice work.That's definetely a change in noise. Did you drop the whole front subframe to access the pans?
Do you still have the normal whine in cold start? I believe that is caused by the gear type in primary pump. Btw, for this XF Motorsport redesigned new gears that seemd to improve noise and floe level of the first pump. There is a new video out of this from XF.

 

Yes, you have to drop the subframe to get the oil pans off. Thankfully the power steering lines are long enough that you don't need to completely disconnect them and bleed the system etc. It's a messy job though, as the oil pump system retains a good bit of oil until you try to remove it, them in dumps probably half a quart of oil all over the place. I'll attach a couple pics. Wish I had taken more but it's difficult when your hands are covered in oil.

The startup whine is still present, and a very low level whine once the car settles down. The gears are still the noisy design, it's just that now they are actually running normally I would say. The whine is just MUCH quieter than before, and you can't really hear it from inside the car with the windows rolled up. That's how my car was prior to a few weeks ago when the noise really started gaining intensity. I suspect for most people, this wouldn't actually net them much of an improvement in the sound unless they are getting the same super loud noise I was getting. If you are like me, it might be worth it for the peace of mind though.

 

Im glad your noise is better and also amazed that the o ring caused it. In my opinion any airation of oil to the bearings would damage them for sure so it's good you got this fixed.
As I had posted a while back when I pulled my engine to do a freshin up I found nothing wrong with anything...pump and seals along with everything else was perfect. Even installing a new pump for the hell of it made no difference.
The oil of course played a huge roll in it.
I can also tell you with certainty that doing something odd after start up will SIGNIFICANTLY lower the noise to whisper quiet in my engine before driving off and learned this by accident. When started, especially cold, if I very slowly keep reving the engine in park/neutral 6-10 times to say 2000 rpm repeatedly the noise will slowly disappear to whisper quiet and not come back for the whole drive. Now there's something to ponder !!LOL It's almost like it has to be primed on the front evac side of the pump.

 

So it appears I may have spoken too soon on the state of the noise. For the first three days after the fix, the noise was drastically improved. When I drove the car tonight, it was back, to a degree at least. It is still far reduced in volume, I would say roughly 1/10th as loud from a perception standpoint, but tonight the car had an unpleasant low level whine that would simply not go away even once the car was completely warmed up. It's much colder than normal here tonight, so that might have had some impact. It's -1.5 C or around 29 Freedom degrees for the non metrically inclined. We've also got black ice, which appears to have caused a major accident on the Autobahn near my home, with a vehicle on fire. Fun fun!

I'll update if there are any further developments. Which Liquimoly type and weight is the preferred for trying to mitigate this noise? Will try to get some in for the next oil change.

 

The colder....the louder.

 

Thanks for keeping us updated. I've only ever used the MB supplied Mobil1 5w-40 so I can't be of any help in that regard. It doesn't get very cold here in Central Florida. You may also want to remove both belts when the engine is cool, run it just for a few seconds to see if the noise is gone. A/C compressor or idler pulleys, along with the occasional power steering whine could also be the source of your noise.

 

I actually did that about 2 months ago when I was hunting for the original noise that turned out to be the pulley bearings. It was quiet without the belts then, which lead to me replacing the bearings, and fixing one noise issue only to have another surface less than a month later.

It's a pain in the *** getting the belts back on without access from the bottom though, as I learned that time around. Ended up having to use the handle of a snow shovel to get the bottom pulley. LOL! It was the only thing I could find that was long enough to reach. I do wonder what my neighbors would have thought if they had come into the garage at that moment to see me sticking a snow shovel down into the engine bay of my car. LOL!

 

I'm running LM Synthoil Energy 0w-40, 120€/10L in ebay. Though, I didn't notice much of a diffrence compared to M1 0w-40. Running LM together with Mos2.
I tried also LM Leichtlauf 5w-40 but with that the noise level was more constant, even in warm engine.

 

Very interesting, mine is very similar to the before sound, maybe not quite as loud, but that could be the microphone. from inside the car it just sound like a whine but standing in front of the car and laying underneath the engine it sounds very similar to yours, like grinding/ cavitation noise, I fell like mine also has an oscillation to it though.
When you had the pan off did you notice if the oil pump chain had been rubbing on the timing case, that seems to be common due to the simple spring tensioner, usually starts cutting into the case, but I wonder if this is one component to the noise? in my case holding a screwdriver to the pan id say it isn't, as its coming directly from the front scavenging pickup which seems to agree with XF's findings .

 

So far ive tried Mobil 1 0w-40, then I tried LM Leichtlauf 5w-40, the I tried a cheaper 5w-40. out of the 3 I would say M1OW-40 was the quietest, like you I feel that 5w-40 is more constant, so am gonna go back to 0w-40 should I do M1 again or LM. LM seem to have 2 versions, but only one I can find in the UK is the Synthoil Energy like you are using, but that only has MB229.3 spec and not the 229.5 spec that is recommended,I dont know if that matters.
I was thinking of also adding either Mos2 or Ceratec, but worried they will clog the oil filter and make it worse.
Weird thing is I never noticed the noise when I first bought the car 2 years ago, it seemed to start the next day when I did the first oil change. Also my dad has an identical car with double the milage and his is almost silent. mine only has 60,000 miles his is like 135,000.
every time I think ive got my head around this I read another post that confounds me again. XF's video seemed to be the answer, that its just the front scavenging pickup and gears making the noise, and if so would be nothing to ever worry about, but if thats the case then why did swapping the O ring on the main pump dramatically reduce the noise on Freeeshta's. Then again If the hardened Orings allow air in bad enough to cause the noise then why is my dads high milage one still silent and my low milage engine noisy as hell.
The other thing that worries me is sometime I think I can feel the noise through the care like the engine feels rougher than my Dads engine.I hope that doesn't mean I have the start of oil starvation from the O ring. I have no metallic shavings in the drained oil or filter, and the oil doesn't even get dirty over the course of a year, so thats a good sign.
I also tested the oil pressure with an external gauge connected to the port on the front of the oil filter housing, I get very strong pressure from cold ( when the noise is worst ) and gradually settles down to about 13PSI when hot, I thought that seemed low but XF tells me thats normal.
Well thats the end of my rambling thoughts for this message, does any of that make logical sense, or have I drove my self around in circles LOL
Lee

 

I couldn't see any issues with the chain in my case. Not sure if you can actually see where it hits that timing cover with just the oil pan off or not, but I didn't see anything that looked out of the ordinary in mine.

Regarding the noise levels, the recordings don't actually do a good enough job showing the difference. It's was way louder than normal before the job. Like dump truck loud. Loud enough to distract pedestrians and make them turn around to see what is coming up behind them as you drive by at 40 kph and 1000 rpm loud. If yours isn't teeth grindingly loud inside the car, then it's probably not doing whatever it was mine had decided to do.

Regarding why one car might be different than another, there are two things I would consider. The first is that there are other items that can make similar noises. I would check your pulley bearings, and your water pump. Both were worn our on my car at 80,000 miles, and both made similar whining type noises until one of the pulley bearings went bad enough to start chattering. You dad's car may have already had these items replaced as they are common wear items.

The second factor is that I suspect Mercedes might have had an intermittent quality control issue with the precision of the alignment on the oil pickup tube and the oil pump itself. These two parts are not bolted directly to each other, they are just held in place in relation to each other by mounting brackets that screw into the bottom of the engine. In my case, this alignment does not seem to be particularly accurate. Basically, there is too much room in the joint between the two to properly compress the O-ring on all sides. It is only being compressed on two sides rather than 4. This may contribute to it failing earlier than on another car where the fitment is correctly aligned.

That said, the main issue is the design of the scavange pump. XF is correct in my opinion, it's just that some other extenuating factors can apparently contribute to making the sound even worse.

 

Ive run both cars with the auxiliary belt off and wasn't any of the ancillaries. Its definitely all coming from the front of the oil pam on mine, yet on my dads car the oil pan is dramatically quieter.

 

I asked oil specs from LM and they stated that 229.3 is specified for 20k intervals and 229.5 for 30k. I'm staying well under that any case.

 

I asked oil specs from LM and they stated that 229.3 is specified for 20k intervals and 229.5 for 30k. I'm staying well under that any case.

 

Well then the only guess I have is that it might be like mine, though mine did not make much noise at all from the oil pan prior to about 3 weeks ago. Really can't be sure as I've only ever seen mine and a few pictures or video from other cars, and mine seems to be the only one that saw a real improvement in sound levels from this procedure so far.

 

oh thats a very good bit of info, if thats the only difference i will give it a go. Its the only one i can find in the uk, though its really expensive compared to mobil 1.

 

well, i wouldnt say mine is as loud as you describe, i can hear it when driving but not if im listening to music. Its enough to be annoying, but when really warmed up, it lessens a bit. If i rev the car i can hear it to 2000rpm then above that it goes away. but now its winter warm up takes a while and driving around town im pretty much always in the 1000 - 2000rpm range so its noticeably most of my journeys. If i go on a motorway journey then the car sounds fine.

 

That's basically how mine sounds on a colder day at the moment. On a warmer day you can only hear it with the windows down. Warmer would be like 45 degrees or so, colder around freezing for reference. That's been about the temperature range I have seen so far.

 

ok after reading this thread i noticed that several of you said something similar that after revving or spirited driving, the noise significantly reduces, so i just went out to try that on mine, the slow revving didnt help so then tried some aggressive revving, then let it drop to idle and indeed the low groaning grinding noise was almost gone. There was still the higher whining noise that changes pitch with the revs ,but i think thats just how they sound. Its the groaning grinding cavetating noise that is what is driving us nuts.
So trying to think about this logically it occurred to me that, could it be that the front scavenging pump is more efficient than the main pump, so consequently the front sump (which XF described as a semi dry sump), is actually getting sucked empty before it is refilled from the main pump via circulation through the engine, but once we start revving it the main pump starts producing enough flow to reverse the situation. I think this could be a very small margin, so at tickover the scavenging pickup is just above the oil level in the front sump hence sucking air, then after revving the level rises enough to submerge the pickup. With this in mind i shut the engine off and left a few seconds before restarting, then the noise was back until i gave it a good rev. This would explain a lot of the weird variations we are seeing, as could it be that after oil changes some of us are adding slightly more oil, enough that the pickup is always submerged. And as these engines dont come with a traditional dipstick, all we are relying on is the electronic level which only has 3 settings, level ok, add 1 litre or remove 1 litre.
tomorrow im going to add half a litre and see what happens then add another half litre, if it tells me its too high i will just drain a little until the high warning disappears, so getting it as high as possible without the high level warning. This could potentially cause issues with leaking from the rear main seal so im not advising anyone to overfill their engines. Just seeams like a good explanation why some of us only noitice the issue straight after an oil change.
please ignore my poor punctuation, ive typed this really fast before going to cook dinner LOL