Hey all,

I recently bought a ultra clean 14 E550 with about 80K on it. Love how this car goes down the road and the plan is to keep it for 4 years which is maybe another 30K miles for me.

I knew the front of the motor had a leak and I negotiated that into the purchase price, now I'm trying to figure out just how much is leaking.

What's grimy:
Alternator
Front of block both sides

What's not grimy:
Turbo lines L&R
wastegate L&R
heat shields L&R


What I observe with my borescope and just looking close with a flashlight I see the left-most magnet is wet on the bottom, and the right most magnet is too. Looking behind where the cam cover meets the valve cover I'm not seeing much oil, the wategates, lines, and shields for the turbo don't look dirty on either side. The left side looks like it is leaking the worst, I was able to see the Alternator housing looking a bit grimy so the oil is getting down that way but I do not see oil pooling on the under tray.

Part of me is thinking to first try replacing the 2 O rings on the outer magnets left and right. Is that worth trying first or should I just pursue resealing both covers, replace 4 magnets and O rings?

 

80kMi with leaking timing covers are to be expected.

Suggested maintenance are:

• swap chain tensioners
• reseal timing covers
• inspect magnet-solenoid leaks (o-rings)
• test VVT Phaser locks
• replace CPS + pigtails
• Vacuum pump check valve
• (thermostat)
• air filters: engine + cabine

In addition to inspect/replace:

• serpentine Belt kit
• ignition plugs + boots
• trainy ATF

100kMi... HPFP + PCV kit

Cali.

 

The VVT window cover often get poor sealant job from MB.
Your leak is common, very common.

Not so easy to re-do the sealant on M278 due to high density of parts in front of the engine, but do it .
Read here : https://mbworld.org/forums/e-class-w...lant-work.html


BELOW :
This is 21,000KM M157 ( bigger sister engine to M278, very very similar ) of model year 2012
If enough teardown done, you will see much more oil leak trace under the mini VVT window.


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If you can see oil there at the under carriage plate, that means the leak is quite bad. Mind you 21,000KM is only 12,000 miles or so.




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GLE400 M276.8 , 3.0 Turbo. 67,000KM




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If your leak is bad or get bad, your alternator may get fried from overheating due to oil coating its winding.
Worst case your serpentine belt get destroyed by oil and then get stuck at the main damper pulley and it will chew the crankshaft main seal and your can get your serpentine belt material into the
engine oil pump...yep, this is insane. 2 recorded case on M276 the serpentine belt entered engine from front main crankshaft seal.
Read here : https://mbworld.org/forums/e-class-w...-teardown.html


This is how M278 nad M276 looks like without much components in front of it. You can see where the oil leak will spread to.



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Have fun fixing the VVT mini window.

 

Thank you for the detailed reply this is very helpful!

My searching has not found this, but do you know of a forum post that covers the timing cover removal in detail for a m278/m157 w212?

I am trying to understand if I need to remove the radiator fan, hoses, or any other items that may be in the way. I would like to know what exactly needs to be removed so I do not need to guess. I have found info for this job on an S class, but since that is a larger vehicle the steps for removal may be different. Any tips for doing this work will be a major help.

I've read conflicting information that the oil filter housing needs to be removed or replaced with a new one, or it may not need to be. Also conflicting information about replacing coolant lines during this job because they may or may not break.

 

Check your car data list with the VIN decoder, use this one : https://www.lastvin.com/

If your car/engine has Code 139, most likely the engine oil filter housing must be removed.




Find attached WIS on what to remove, to access mini VVT window.

I use main file : M278 - Timing Chain tensioner ( remove-install) and the rest of the linked documents.

Try to go to Ebay used engine for visualization, as they have good high res photo and sometimes complete or semi naked engine to help you see components clearer
Remember there are minor difference between M278 earliest model to latest model and on what car it is installed. Example the cooling circuit on oldie M278 only has
1 coolant recovery bottle fo radiator, where turbo aftercooler shared with it. Later the turbo aftercooler get its own recovery coolant bottle, thus the engine then have 2 separate cooling system.
Maybe the Code 139 meant the dual cooling system...maybe. I am not familiar with M278/M157 like I do on my own M276.820.

Ebay 1 : https://www.ebay.com/itm/22695970702...Bk9SR6CS84izZg

Ebay 2 : https://www.ebay.com/itm/18685347938...Bk9SR6aS84izZg


Good luck............

 

M278, while you are in there, replaced all the turbo related cooling pipes which has plastic ends, which will break soon, a 100% guaranteed.
Search this forum.A lot of info for it.

 

My $0.02…I’ve done this job on my 2014 e550 coupe and my 2015 e63s sedan. FWIW, I agree that you do or will soon enough need to do the full job.

That said, there is certainly no harm in ordering the super cheap set of four new rubber o-ring gaskets to install on the cam magnets. It’s important as always to observe torque values on the magnesium cam cover plate bolts and replacing the one-use bolts is recommended. The pro tip for cost savings is to find the cheaper identical bolts sold for the BMW ($1/ea vs $4-7/ea).

Regarding the full job, I have bunches of pics and parts list if needed…just depends on how capable and comfortable you are with diy…and how much time you can have afford to have car immobile. The passenger side (US) bank is an easy-ish job, much less to remove to detach plate and reseal. The driver side is pretty involved. Some say they have found a way to avoid removing oil filter housing via specific wrench…I could not for my m278 coupe.

Also, your oil filter housing gasket WILL leak and need replaced soon, if not already. In order to remove it though, you WILL have to remove your turbo coolant lines, thermostat, upper rad hose. Your thermostat will break or is already broken, and you will find your water pump needs replacing. SO, as you’ve likely read already…it’s a pretty deep rabbit hole. For less than $1500 in parts you can do the full refresh and save $6-10k in labor from dealer…but it’s not an easy job

 

Going to replace my tensioners and check valves soon on my M278. I've seen video where a gentleman did not remove his oil filter unit and was successful. I plan to use the same approach. Otherwise, same as above post. Just put the car in the garage and start working. Drive the beater till it's finished.

 

Thanks for the great replies very helpful. I have the time and space to work on this I guess the next thing I need to figure out is where to find the part #'s for the oil coolant lines. I found the Oil housing gasket and thermostat on FCP but struggling to find the lines

I replaced the crank position sensors yesterday, all 4 had oil in them. I pulled the connectors on the ecu and the connectors were dry, whew!!! The wires to the magnets were dry thankfully, but I put the sacrificial pigtails on the magnets because why not.

 

Go to here :
https://www.amayama.com/en/genuine-c.../mercedes-benz
or

https://nemigaparts.com/cat_spares/epc/mercedes/1/

Insert your VIN for the search.


Best is.................. buy in ebay knock off EPC/WIS of 2020.


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Best price for genuine MB from real US MB dealers, among others
mbpartsource.com
mbpartsexpress.com


Good luck