Oil for MB with *warm* start knock issue

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60.000 miles and it knocks. Yep, German cars are great. I would add something like Cerrocoat or some other slippery stuff to help keep it going.
Good luck.
 
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60.000 miles and it knocks. Yep, German cars are great. I would add something like Cerrocoat or some other slippery stuff to help keep it going.
Good luck.
The M273 engine isn't that common, they didn't sell that many of them although it was basically just the V8 version of the V6 engine which was much more common. With that said, this is not a common problem, haven't really heard much mention of this in the E class forums. It's probably why you see more mention of it in the C class forums, they sold a lot more of those and those reference the M272 engine.
 
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I didn’t know it was a common issue. My car, 08 E350 with a M272 has the same issue, though I am at a tad over 180k miles. I’ve had it for about a year now and thought that it was lifter noise or that it was just me hearing things. The owner before me used Motul 15W-50 for at least 3 oil changes as recommended by the shop he serviced it at and the first thing I did was to put Mobil 0W-40 in it. I change it every 7500 miles because the OCI in the car is set for 15000 for whatever reason. Since I though it was lifter noise I purchased Liqui Moly Leichtlauf High Tech 5W-40 to give it a try but looking at VOAs it doesn’t seem like the best thing to do. Any suggestions?
 
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I didn’t know it was a common issue. My car, 08 E350 with a M272 has the same issue, though I am at a tad over 180k miles. I’ve had it for about a year now and thought that it was lifter noise or that it was just me hearing things. The owner before me used Motul 15W-50 for at least 3 oil changes as recommended by the shop he serviced it at and the first thing I did was to put Mobil 0W-40 in it. I change it every 7500 miles because the OCI in the car is set for 15000 for whatever reason. Since I though it was lifter noise I purchased Liqui Moly Leichtlauf High Tech 5W-40 to give it a try but looking at VOAs it doesn’t seem like the best thing to do. Any suggestions?
What in the VOA exactly do you see that makes it not "the best thing to do"?
 
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The lack of molybdenum in it. I will be testing it out anyways though since I have already purchased it. Maybe I’ll be proven wrong. I am in no regard an expert in the field.
 
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The lack of molybdenum in it. I will be testing it out anyways though since I have already purchased it. Maybe I’ll be proven wrong. I am in no regard an expert in the field.
Ahh I see. You question the ability of Liqui Moly to properly formulate an oil to achieve Mercedes-Benz 229.5 approval.

How are you planning on testing it to see if it doesn’t meet the approval requirements?
 
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I am sure they can make good oil, I am not questioning their abilities. By testing it I meant I will be putting it in the car and observing.
 
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Price always go down over time but I suppose it will reach a point where they will start to go up again. Plus all it takes is one idiot on the road to smash your ride. Probably premature to buy an engine although I suppose you could always turn it into a table stand.
Yes, its all fun and games until somebody hits your beloved car, I still miss my 2.5 SEL Jetta!

I had just replaced the ATF too! The expensive ravenol stuff too!
 
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I had an '08 C300 (6 spd manual!) for a few years that exhibited this low-end knock on warm startup, just a second or so. I had read plenty of other stories on the MB forums where I'm still a member and came to the conclusion that it was not very common, but neither was it detrimental.

As overkill summarized it earlier, MB had been made aware of this issue to the point where they replaced main bearings in some cars. For a few owners, that solved the issue but for many others it didn't. I think MB ended up throwing their hands in the air and concluding "it's normal."

Most of those folks either sold or traded those M276-engined cars long before any failures ever happened, but the noise was keeping them up at night (probably because of forums like these).

I would experiment with different 229.5 spec motor oils and see how the noise is. Ideally there shouldn't be much difference across brands that are approved for a given spec, but we know oil mfrs blend oils differently to achieve a given spec.
 
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That's what I was planning on doing. Just wasn't sure what to try after the Liqui Moly Leichtlauf High Tech 5W-40. I was thinking either 5W-40 Formula M or the Castrol 0W-40 that can be obtained from Walmart.
 
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I have exactly the same startup noise, so thank you very much for posting the recording. I'm the second owner who bought my '08 E350 at 18k miles. I first noticed the knock at 33k miles and now the car has 54k and the sound hasn't really changed. When I first heard it years ago, it was an alarming thumpa, thumpa, thumpa . . . for five seconds. Now, it's more just thump, thump, thump, thump for 2-5 seconds. I've decided to stop worrying about it, for the following reasons.

I've tried a number of remedies, but nothing helped at all. I've used Sea Foam Motor Tune-UP in the crankcase, flushed the crankcase several times with the service at Valvoline, and used Marvel Mystery Oil in the crankcase for 3k miles, all while the car was in the 30'sk miles. I tried a number of different oil filters. I always used Mobil 1 European 0w-40, changing it ever 2k miles, and added Liqui Moly Mo2 for the last 5k miles. I just switched to Redline Premium 5w-30, with Rislone Nano Prime additive. I replaced spark plugs. I used all sorts of Techron, acetone, Marvel Mystery Oil, Liqui Moly Valve Clean in the gas. As I said, nothing made any difference, although all the treatments greatly improved idle, pick-up acceleration, gas mileage, transmission shift points, even cured oil leaking from the rear camshaft seals.

I agree that it's probably main bearing noise, but might also be camshaft bearings. After a lot of research, I've concluded that it really is just harmless noise. I read a Ford repair manual and watched a GM service video about the subject of bearing noise, both of which discussed startup knock. They explained that modern engines have much tighter tolerances than the old V8's of the 1970's. A crank bearing today will make noise when it's out-of-tolerance by only 1 micron, compared to the old rule-of-thumb of 3 microns. Both GM and Ford explain how to compensate with oversized bearings, but both also say that it is unnecessary and will not cause any long term damage. The parts are apparently very durable and there is just not enough torque or friction at startup for wear to happen.

What caused the problem? Hard to say. It may be a manufacturing defect, because reporters sometimes used to notice the horrible sound at publicity events when an E350 had only 7k miles on the odometer. It might also be damage from carbon pack, based on another video I watched on YouTube. After all, my car did have carbon buildup and hesitation problems when I first got it, which I've read is typical for this particular model. In any case, there is inherently more stress on the front-most main bearing due to the accessory belt pulling on the engine, so the front main commonly wears more than the others (according to the GM video).

Finally, I've never been able to find anyone who had this sort of startup knock and then reported catastrophic failure. There are no pending class action lawsuits pertaining to the matter. One person in this tread has an M272 engine with the noise at 180k miles. Another owner even had the noise simply disappear with time! In my case, it certainly hasn't gotten any worse in 21k miles.
 
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Wow, that other thread is wild!

Multiple different issues, some folks had cold start knock, a couple of them had the same as you (warm start knock) and two people had their main bearings (and who knows what else) replaced but their noise was getting worse. One guy had his timing chain guides replaced, but his noise seemed to last longer (5-10 seconds) and it seems most people just live with it if it doesn't get worse. Another guy had his oil pump replaced due to low oil pressure (which didn't help, this DOES point to worn bearings) and the one guy that had his bearings replaced had another Merc that made the same noise but it self-rectified :ROFLMAO: Somebody asked him to provide a list of what was actually replaced, but he never got back on that.

So, it seems that going through the process can indeed result in the noise being eliminated. Depending on the cost, if it isn't getting worse, it might make sense to just keep an ear on it. On the other hand, if it is driving you nuts, it sounds like going through the process of getting the mains replaced has yielded some success for those who have followed-through with having it performed so it may make sense to do so. No wizard in a can is going to help (and that was covered in the thread, heavier oil did NOT improve things) so either live with it for now or get the work done.
Could it be a piece of sludge in one of the oil holes in one of the bearings?? The car did sit a lot. Also MB has had problems over the years with engine parts not being properly hardened by their suppliers. I agree with the idea of taking it out on the interstate for a long blast.
 
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That's what I was planning on doing. Just wasn't sure what to try after the Liqui Moly Leichtlauf High Tech 5W-40. I was thinking either 5W-40 Formula M or the Castrol 0W-40 that can be obtained from Walmart.
The Mobil 1 5-40M was/is made specifically for MB. It wouldn't hurt to give it a try.
 
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I've tried a number of remedies, but nothing helped at all. I've used Sea Foam Motor Tune-UP in the crankcase, flushed the crankcase several times with the service at Valvoline, and used Marvel Mystery Oil in the crankcase for 3k miles, all while the car was in the 30'sk miles. I tried a number of different oil filters. I always used Mobil 1 European 0w-40, changing it ever 2k miles, and added Liqui Moly Mo2 for the last 5k miles. I just switched to Redline Premium 5w-30, with Rislone Nano Prime additive. I replaced spark plugs. I used all sorts of Techron, acetone, Marvel Mystery Oil, Liqui Moly Valve Clean in the gas. As I said, nothing made any difference, although all the treatments greatly improved idle, pick-up acceleration, gas mileage, transmission shift points, even cured oil leaking from the rear camshaft seals.
I wouldn't go too crazy trying to find the magic oil that will fix it. At least use 229.5 oils, there's only one Redline 5w40 that meets 229.5. Your Redline 5w-30 does not. I would just stick to either Castrol 0w40 or Mobil 1 0w40. You can try Mobil 1 Formula M 5w40, it's what the Mercedes dealers carry and use in the AMG engines too. I'm not sure the extra cost over regular Mobil 1 0w40 is worth it though. And 2k is way too often, many people get 100k+ or more just doing regular 10k oil changes. MB used to do 13k oil changes but people couldn't stand it that long so they went back to 10k oil changes.

 
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Aug 9, 2021
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Thanks for the tips. I might try Mobil 1 Formula M 5w40 next time. I used Red Line High Performance 5w-30 based on the recommendation of the Red Line site. Red Line considers it better than the Professional Series that MB approves. I've decided to use the Rislone additive because I've read that the combination of tungsten and molydenum are the very best for ant-wear and anti-friction.

I understand that I'm changing the motor oil too often. I change it every 2k based on how black the oil becomes. The motor seems to run at a very low rpm and, given the occasional short, slow trips my mother takes to the supermarket, there seems to be a lot of carbon buildup throughout the engine (think cold, smoky combustion plus blow-by). It's why I had to use all the flushes 20-30k miles ago. I've read that the black color is mostly due to soot, which turns to sludge after enough heat cycles. Now, the car never loses pick-up with the frequent oil changes together with Marvel Mystery Oil and Star Tron Enzyme Fuel Treatment Concentrate in the gas tank. Also, I change the air filters every 2k miles, because they appear to clog that rapidly (just hold them up to the sunlight and see for yourself).

I welcome all of your analyses. I've come up with this routine after a lot of experimentation. It's the only way I seem to be able to keep the engine acceleration fresh without all the crankcase flushes, additional fuel additives, and harsh "Italian tune-up" blasts at wide open throttle.
 
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End play on the crank shaft? A non problem as long as the seals last Had a worn thrust bearing in a Jeep V8 upon cold start up.. Sounded terrible for about 3 knocks then went silent.
 
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Thanks for the tips. I might try Mobil 1 Formula M 5w40 next time. I used Red Line High Performance 5w-30 based on the recommendation of the Red Line site. Red Line considers it better than the Professional Series that MB approves. I've decided to use the Rislone additive because I've read that the combination of tungsten and molydenum are the very best for ant-wear and anti-friction.

I understand that I'm changing the motor oil too often. I change it every 2k based on how black the oil becomes. The motor seems to run at a very low rpm and, given the occasional short, slow trips my mother takes to the supermarket, there seems to be a lot of carbon buildup throughout the engine (think cold, smoky combustion plus blow-by). It's why I had to use all the flushes 20-30k miles ago. I've read that the black color is mostly due to soot, which turns to sludge after enough heat cycles. Now, the car never loses pick-up with the frequent oil changes together with Marvel Mystery Oil and Star Tron Enzyme Fuel Treatment Concentrate in the gas tank. Also, I change the air filters every 2k miles, because they appear to clog that rapidly (just hold them up to the sunlight and see for yourself).

I welcome all of your analyses. I've come up with this routine after a lot of experimentation. It's the only way I seem to be able to keep the engine acceleration fresh without all the crankcase flushes, additional fuel additives, and harsh "Italian tune-up" blasts at wide open throttle.
Wow, way too much work on the car. I just use Mobil 1 or Castrol 0w40. Whatever is on sale. Had some Pennzoil 5w40 a while back and even Castrol 0w30 at one point when it was $2 a quart. Have over 120k on one M272 engine and 130k on the other. I tend to change it between 8-10k. The black color is due to oil doing it's job and keeping the engine clean. The cars hold 7.5-8.5 quarts of oil so it's not like other cars which only hold 4-6 quarts of oil. I don't use any gas additives either but you could just stick to top tier fuel which has Techron in it. Costco is also top tier. You can also try the transmission ECU reset, that actually wakes the engine up more than anything you're doing. Tends to get sluggish after a while. Have you changed the oil separator? I'd also keep an eye on the oil cooler gaskets and the 3 rear oil plugs along with the oil breather cover.
 
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Thanks for all the feedback, Wolf359. I did just what you are saying on this E350 when we first got it and on a previous ML320 for many years, and both cars developed lots of rough idle, oil leaks, hesitation. It might be that these cars are "granny-mobiles" that are only driven occasionally by senior citizens. My regime, which includes a five-minute flush, seems to eliminate all the problems. We use the MMO and Star Tron all the time. The oil & filter changes amount to twice a year, given the low usage, which is what manuals seem to suggest anyway.

Thank you so much for the maintenance tips pertaining to the oil cooler, plugs, and breather cover. I'll Google the replacement procedures, but I'm open to your experiences.
 
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I wouldn't go too crazy trying to find the magic oil that will fix it. At least use 229.5 oils, there's only one Redline 5w40 that meets 229.5. Your Redline 5w-30 does not. I would just stick to either Castrol 0w40 or Mobil 1 0w40. You can try Mobil 1 Formula M 5w40, it's what the Mercedes dealers carry and use in the AMG engines too. I'm not sure the extra cost over regular Mobil 1 0w40 is worth it though. And 2k is way too often, many people get 100k+ or more just doing regular 10k oil changes. MB used to do 13k oil changes but people couldn't stand it that long so they went back to 10k oil changes.

I just spoke to an engineer at Red Line (Dave, (707) 751-2914). He said that the Red Line Performance Series does, in fact, meet MB 229.5 standards, as the Red Line website states (see OEM Compatibility tab). Red Line does not submit the Performance Series to MB (only its Pro Series), so that's why it doesn't appear on the official MB 229.5 list. Submitting the oil to MB would drive up the cost prohibitively. Dave also said the Performance Series contains only Class IV & V base oils (not Class III like many other major "synthetic" manufacturers). In Europe, anything containing Class III can't be labeled "synthetic." Those other oils for half price never mention how much Class III they contain! Also, the NOAK number published by Red Line is indeed ASTM D5800 and it blows away Mobil 1, Pennzsoil and the others.

I don't know about you, but I'm only using Red Line from now on. I don't care if it's twice as expensive!
 
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