a4ncar

My 2012 E350's oil dipstick keeps popping up, first, it was doing every couple of weeks, now it has become almost every few days. Back in August of this year when my CPO was expiring, the dealership said they replaced the motor and transmission mounts, and they said it should take care of the problem. The problem is still there and has become more frequent in the last few weeks. Anyone experienced, the same problem with their W212? Mine only has little for 52K miles. I am no longer under warranty, any ideas where should I begin troubleshooting this problem? Thanks

Ray

KEY08

Excessive crankcase pressure can cause the dipstick to pop out. Let’s hope it’s just in need of a new O-ring on the dipstick

kajtek1

Clean crankcase ventilation pipes.
Than you can always make easy blowby test
On stopped engine, remove oil fill cap and put a napkin over it. Start the engine and observe if the napkin stays.
When napkin gets blown away, put a cardboard on the hole and observe if it stays.
When cardboard gets blown away, start looking of new car.

Arrie

I'm used to see car engines to have crank case vent tubes connected directly to the engine intake that should take care of any pressure caused by piston ring blow-by that even new engines can have. Don't these MB engines have this?

95Sinned420

How high does the dipstick pop up? I noticed after doing an oil change, my dip stick was about 3-4 inch high. I thought hmm.. maybe I forgot to push the dip stick all the way down the last time I checked the oil? But... that is very unlikely. I then put it back and drove it a few days, dip stick remains in place.

I never knew this cold happen, how do I check if anything is clogged? I will try the cardboard test and see if I need a new car lol 😂

ygmn

Agree...

PCV system needs to be checked

kajtek1

MB never made direct connection for crankcase ventilation.
At least not for last 50 years. Even W123 diesel had complicated drainage system that would separate the oil and dump it back to the pan.

a4ncar

I am surprised that I am the only one with the problem. It does not look like the O-ring on the dip can be changed. I will start with a new OEM dipstick. Does anybody have a part number for 2012 w212 oil dipstick? Thanks.

kajtek1

Did you read the replies at all?
New dipstick can cover the results, while it will not do anything for the issue.

a4ncar

Yes, I did. I was going by the fact that the O-ring on my dip stick looks very stiff and brittle. I can do the napkin / cardboard test before, I order the dipstick. Looks like local dealer wants $67.50 plus tax. Thanks

a4ncar

Just did the napkin test as-is , and it seems that it wants to get sucked in, did not clean any pipes as was not sure which ones.

atraudes

That's good, you should have a very slight vacuum. Given that, you don't need to clean the PCV hoses.

If the o-rings on the dipstick have shrunk due to age, I could see the dipstick working itself out over time from vibrations. I want to say mine works itself up a few mm over time too so mine probably needs attention as well. One could probably just source new o-rings instead of buying a whole new dipstick. If you were feeling like a champion, you could pull an o-ring off your new dipstick and measure the diameter as well as how thick it is and post it here for posterity

DFWdude

As suggested I would replace the o-ring first. This will be a metric o-ring, and you can find it here... https://www.applerubber.com/src/pdf/...ze-o-rings.pdf

If you have a Harbor Freight nearby, or an Ace Hardware, you can buy single o-rings, or sets for little money. I'd be tempted to measure the old o-ring or take it with you to the store, and try a slightly larger one (metric or Imperial), to see if it seats more securely. For the price of an o-ring (10-15¢) you can experiment. It would be silly to buy a new dipstick just to solve an o-ring problem.

I buy o-rings all the time for my Air Rifles that work on compressed air. Here in Dallas I buy from H&D Distributors (214) 351-1251. They ship all around the country... http://www.hddistributors.com/ Or you can shop the o-ring store... https://www.theoringstore.com/

dacia

I have the same issue, 2014 E350 with about 50K miles.
Haven't found a solution yet. Started doing it recently.

Arrie

Could the problem be that the oil level in the engine is just slightly too high. This would mean the level covers the end of the dip stick tube. Then when oil heats up it also heats up air in the tube and because of the O-ring builds up enough pressure in the tube and pops it out?

An easy way to see if that is the case would be to lower oil level as it should be very safe to operate with level at half way between low and high.

Another way would actually be to remove the O-ring so the pressure can get out without popping the stick out.

Then, of course, if the O-ring can be changed an O-ring could be used that is so tight the small air pressure in the tube cannot pop it out.

I'm saying this as the crank case should be under small vacuum when the engine runs and there should be no force to press the dip stick up from its place and the only place such force could build-up is the dip stick tube itself if the bottom end of it is sealed, what a high oil level would do.

a4ncar

I just changed the dipstick, and the problem went away. The o-ring, on my OEM dipstick was pretty stiff plastic and I would have Dremel it out. I got a febi dip stick and it has softer rubber type o-ring. Thanks for your input.

Isawelvis

Not that I have this problem but all the recommendations and comments were outstanding. This is the reason we are members of the site. A lot of experienced and smart people out there.

kajtek1

I think new oring, holding the dipstick firmer covered the symptoms, not the issue.
How the blowby test shows vacuum and driving blows the dipstick up?

DFWdude

There are several types of o-rings. Most are synthetic rubber, made from petroleum elements.

When most o-rings get exposed to other petroleum products, they will "entrain" (absorb) some of the oil through pores in the surface of the oring, or most typically through the spot where the o-ring is cut from the casting sprue during manufacture. Especially true with Buna rubber o-rings.

This makes the o-ring swell, which may be the reason the dipstick rises in the tube... The rubber swells and pushes the stick up. But if contained within the dipstick tube, the oring will just get brittle over time. In short, it may seem like stiff plastic, but it isn't. It's a type of synthetic rubber, just like mine is. Try to pick it out of its place on the old stick with an ice pick, and it should break into several pieces without much prying.

This is a good reminder for all of us, though, to use a rag to clean any oil from the dipstick o-ring before each reinsertion in the tube. Just a swipe is enough.

I hope you didn't spend a lot of money on that new dipstick. I can all but guarantee you don't need it.

95Sinned420

So, my dipstick made its way up 3-4 inches again. I’m not sure what is causing this, the o-ring seems fine because the dipstick stays fairly snug. I don’t think it’s the pressure that pushes the dipstick up that high, that’s a lot of pressure? I mean once I pop the dipstick out, there’s quite a bit of friction to pull the dipstick up another 2-3 inches. It seems like the dipstick somehow wiggles itself up, from vibrations?
Any thoughts?

mercerized

I am experiencing this phenomenon recently too. My dipstick o-ring is hard and unusually flat on the contact surface. I suspect that a new dipstick o-ring is more round.
Here is the part number for M276 engine dipstick 276-010-18-72

DFWdude

I changed the oil on mine last week. I use the extractor method (through the dipstick tube). The dipstick was fully seated in the tube before I pulled it out, exactly where it was when inserted more than a year ago.

As for rising 3-4 inches, I'm not convinced there is that much clearance under my hood.

95Sinned420

Attached is a pic of my old dipstick having risen. I ordered a new dipstick, which has a different handle. It fits a lot tighter so I hope it fixes the issue. However, the new dipstick is slightly longer, by maybe half an inch... I'm worried about inaccurate reading now lol

Alandf

I'm an older car guy and I agree with the posts about high crankcase pressure. If the emissions system is clogged with by a faulty PCV valve or even an EGR valve then the fix is not bad. If I recall, direct crankcase vent tubes ceased to exist when PCV valves were introduced to reduce pollution ....so forget that line of thinking. I doubt it is a dipstick problem.
As was stated by other posters you may be getting to much blow by , which means piston rings.
Sorry for your problems.

Tump43

HI, a4ncar's 2012 w212, E350 has a factory installed catch can. It fits just under the intake tube supported by a plastic housing attached to the throttle body. On Saturday I removed mine from my 2014 w212, E350 (same engine) and drained the collected blow-by oil from 90K miles of driving. In my case I didn't have too much blow-by oil, but I can envision how if that catch can was filled beyond capacity (its small) it could increase pressure. Also, overfilling the engine with oil is just as bad (don't ask how I know).