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W164 ML350 M272 oil pump pick up tube o ring replacement
So I've been searching for a how to for the oil pump pick-up tube o-ring replacement on my 2007 W164 ML350 (M272 V6), with no luck (It needs to be specifically for this engine/chassis setup).
There's plenty of talk about this o-ring, as people are experiencing the rumble/rattle on cold start ups because of it, and even confusing it for chain rattle in some cases.
Now I usually just get stuck in and figure it out, but in this case there are a few important questions I need answered before I begin, since I'll be taking care of a few other items at the same time and don't want to get stuck or revisit any stage (If anyone can answer for both the M272 (V6) and M273 (V8) engines this thread may help more people):
1. Do I need to remove just the lower oil pan, or both lower and upper pans, to access the pick up tube o-ring? 2. Do I actually need to lift the engine to remove the lower/upper oil pan/s? I ask this because someone somewhere mentioned that it's not necessary with the V6. And if you look at it, it does seem like it could just slide out from the front (but you never know how much its obstructed from the inside until you've opened it). 3. If I do need to lift the engine to remove the pan (again, in my case its the V6), can I just access the pick up tube by simply dropping the oil pan and leaving it in place? 4. Anything else worth doing while the oil pan is out?
Thanks a bunch in advance.
I did find in my searches, this video which is helpful. It doesn't show if the engine is lifted or not to do the work, but good pictures at the end of the video to help.
Thanks Maj. I'm not sure which lines you mean (when you ask if they look familiar), as I've not actually opened anything up yet. But these pdfs state they're for the m272 and m273 engines. And they confirm one thing...looks like I will need to lift the engine
If anyone's got any further tips, especially regarding questions 3 and 4, that would be much appreciated as well.
There is no video how to replace the ring. I looked everywhere. Someone please take some pictures ar vid whiles replacing it.
You're correct. I never found one and got stuck in thanks to the instructions shared by maj. Ended up undoing 4 bolts for the back engine mounts and jacking up the engine with wood and jack under tranny pan, to just about give enough clearance and using a variety of sockets and wrenches to get all the bolts off and on for the oil pan. Not a job I'd wana repeat just for an o ring.
Since then I've had some new rattle on warm startups, followed by a constant ticking when driving, which can only be heard within the cabin. And another sound when i first set off from a cold start coming from the engine, which sounds like a release of some sort of liquid pressurised somewhere, almost the liquid sounding equivalant of a bus's air suspension "tshhh" sound. And I've decided I'm done with mercedes. Unless i ever find a low km 2000 era model that I like.
From 2000 till around 2003 they had strange rust issues.
2003 was just a terrible year for them.
Then they had valeo rad issues which resulted in busted trannies, which took them years to resolve (if they ever did resolve them).
Then the tranny control module issues from 2005, which i don't know if they were ever resolved, cos they were still present for a few years. Oh, and of course the module is a security part that's inside the tranny.
Then chain/chaintensioner/check valve issues with many engines, for many years, which I don't know if they ever resolved.
then head bolt issues on at least i believe the m156 amg engines....
I could probably go on if I spent more time on this. Lol. Not the kinda issues you should expect from what used to be Mercedes Benz. And bare in mind, mine is a meticulously maintained example.
Last edited by Ontheball247; Mar 20, 2021 at 03:59 PM.
Don't even start....
I'm about to get SATA 4-Piece E-Torx Box Wrench Set - ST09012SJ from amazon. Look it up. Do you think this might save me from lifting the engine?
Can anyone confirm screw e-torx #? is it E10?
How long those screse are?
BTW im doing it on 2008 R350. And have the issue for a list 1.5 year. Winter time is the worst.
Hi. Well if your car is an R350, I'm afraid I couldn't confirm, as the setup might look a little different. On the ML, the bolts are too long and too inaccessible for any tool to help.
Unfortunately the R, although a good and very spacious car in all 3 rows (my uncle had one), is quite rare. But I hope someone out there has experience with this, who can help.
The sound is gone!!!!
You will need to lift the engine 100%, the black pipe just wont let you to pull out the pen. Lifting the engine was pretty easy. Only 4 screws, accessible from the bottom. You will need to remove engine air filter.
i think i lifted the motor about 3 inches max. Ive used the pipe and 12ton jack.
Also 100% you will need e10 and e12 wrench not the socked.
@Bogdandr1 , Have you removed any of the engine mounts to lift the engine that much? or just the 4 screws of the stabiliser bar ?
Thank you for the informations!
You don't actually removing the mounts from the motor. You need to unscrew the mounts from the bottom and lift the engine as much as the top of the engine allows you. I was afraid doing this too, but that's the easiest part of the process. After you done you lower the engine and it goes back to its place and you will need to put the screws back. It's very simple.
I did this on my 2008 ML350 4matic, 178k miles. It was a waste of time. The "thump thump thump" sound on starting is still there. That noise is caused by the upper crankshaft bearings and there is a tech bulletin from MB to replace only the upper half bearing shells with tighter clearance ones to remedy the noise. Too much work for a 178k mile engine...It's been running fine this long, why bother?
Last edited by E55Greasemonkey; Jun 16, 2022 at 08:56 PM.
The sound i had would be difficult to describe in one word. It would appear only after car sits over night in cold weather. Also it dont last long, just a few sec but it sounds bad. It sounds like something lost tension. In my understanding when that O-ring going bad it lets air get in to the oil system. And when you starting the car that air gets pushed out by oil pump and everything runs ok after that.
dose this o ring case knocking sound when engine warm up
it used to rattle on cold start for a while but now it dose not but there is knocking sound when engine worm up
Last edited by RASS EGLEIS; Jan 17, 2023 at 07:51 AM.
dose this o ring case knocking sound when engine warm up
it used to rattle on cold start for a while but now it dose not but there is knocking sound when engine worm up
The rattle sound last 10-20 second on firs start after a cold night. It will not repeat during the day anymore.
If you have sounds on warm it might be something different.
dose this o ring case knocking sound when engine warm up
it used to rattle on cold start for a while but now it dose not but there is knocking sound when engine worm up
This is common for M272 engines, unfortunately, I think its cylinder scoring but it seems that it doesn't affect performance for tens of thousands miles. Actually, i've never heard or seen anyone had trouble because of it. It's annoying, but i don't think it's a problem. Many people posted videos about it. I've had the noise for thousands of miles and nothing changed. Im not burning any oil too, engine has 115k miles, mostly city. So there's that, if we're talking about the same noise.
This is common for M272 engines, unfortunately, I think its cylinder scoring but it seems that it doesn't affect performance for tens of thousands miles. Actually, i've never heard or seen anyone had trouble because of it. It's annoying, but i don't think it's a problem. Many people posted videos about it. I've had the noise for thousands of miles and nothing changed. Im not burning any oil too, engine has 115k miles, mostly city. So there's that, if we're talking about the same noise.
This is he noise. Mine is now doing it. It's a 1/2 second on cold start only
Update- so the total cost came out to $680. $580 for labor and $100 for an oil change since the pan was drained and removed.
The mechanic told me the O-Ring was hardened and he had a little bit of a hard time getting it off the tube.
When they started the car the next day, they said the noise was not present. I have yet to test myself because as soon as I drove the car off the lot, I heard a clunking noise so I went back to the shop. My left strut spring broke so now it's there getting the front struts replaced. I heard a very minimal knocking noise for about a week and I think the strut spring finally broke. What a horrible sound. Yikes.
I should get the car back tomorrow so I will provide another update in a few days but I have a feeling the O-ring replacement did the trick
I can now confirm changing this O-Ring FIXED the cold start rattle issue in the mornings.
This is what my old O-Ring looked like- hard and flattened
Thanks to bogdandr1 for this thread and detailed picrures. I had to print his pictures in order to show my mechanic what I need changed.
I should also mention that it took a few calls to indy shops to find someone who was willing to do this for me. I was asked why I want to change this part, how it won't work and how I should't listen to message boards/online forums.
Middle finger to all of them...
If it wasn't for these boards, I'm highly doubtful they would have been able to find the issue. They would have recommended expensive repairs.
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