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Hello everyone, im own first mercedes c class 350cdi 2012 195kw , never had one before. And i having issues with oil consumption, read somewhere that v6 engines likes oil, but my mercedes uses it like realy a lot. So i owned it not so long, and i noticed that burns oil, every couple weeks i need fill oil in it. the dipstick show less than minimum. So maybe someone know where to start look the problem? i looked in engine section no oil, tried to take the air filter to see turbo condition but i saw oil in air filter tried to read what issue can be on internet and i found that maybe the breather is bad. So what you guys think?? Or its worn piston rings?
I have one with 140k that I got just a couple months ago. I had horribly dirty air filters and figured it may be sucking oil thru the pcv tube and Im assuming it was a little since it went from going thru 2 qts of oil every 200 miles to 1 qt every 250 miles with clean new K/N air filters. Mine always has codes for DPF regeneration frequency so it is in a shop getting a full DPF EGR AD BLUE delete tune and DPF/CAT delete pipe. With high pressure between turbo and DPF many diesels push oil past the turbo seal which is really just a snapring sort of ring amd not much of a seal in the sense that we think rubber or bushing seal. Hopefully mine is fixed this week.
I have one with 140k that I got just a couple months ago. I had horribly dirty air filters and figured it may be sucking oil thru the pcv tube and Im assuming it was a little since it went from going thru 2 qts of oil every 200 miles to 1 qt every 250 miles with clean new K/N air filters. Mine always has codes for DPF regeneration frequency so it is in a shop getting a full DPF EGR AD BLUE delete tune and DPF/CAT delete pipe. With high pressure between turbo and DPF many diesels push oil past the turbo seal which is really just a snapring sort of ring amd not much of a seal in the sense that we think rubber or bushing seal. Hopefully mine is fixed this week.
i dont get any codes of DPF. Sometimes see some white smoke when pushing aceleration harder. So right know im thinking of PCV change.
Just FYI I have installed oil catch can and I catch around 1 liter of oil per 1500km. I also replaced PCV valve with new genuine one, but still same result.
Just FYI I have installed oil catch can and I catch around 1 liter of oil per 1500km. I also replaced PCV valve with new genuine one, but still same result.
well, maybe the turbo burning, do you tried to check condition of it ? Thinking check engine compression maybe worn piston rings... what im afraid of. Im curious how much it will cost for me if that the case..
MB engines don't worn pistons, although S**t can happen.
You can do simulated compression test under "smoothness test" on modern scanner.
I see only 2 possible explanations
1. you have a leak that you don't see
2 loose turbo burns the oil.
If there truly is a loss of compression you might notice it in several ways: poor ignition during cold, loss of power, and possible extra black smoke due to extra fuel being unburnt. Remember diesels fire on compression and lower compression means a less efficient ignition.
This can also cause oil consumption by sucking oil thru the pcv hose when there is too much restriction from the filters. This GL350 was religiously serviced by the dealer and had all services performed on time. Apparently they didnt do air filters.
With basically no blowby at all but was going thru oil at about a quart to 100 or 200 mile rate. Oil usage is less with the new air filters but still quite heavy. Turbo shaft play in and out is just a few thousandths which is fine and side to side is normal. Since the dpf is clogged quite a bit I am doing a delete pipe and tune as we speak and hopefully with less pressure beteen turbo and DPF it will lessen oil usage , if it is indeed pushing oil past the turbo seal. My hopes anyway for a cure.
This can also cause oil consumption by sucking oil thru the pcv hose when there is too much restriction from the filters. This GL350 was religiously serviced by the dealer and had all services performed on time. Apparently they didnt do air filters.
Good point. Coming to dealer service, I bought 2007 E320 Bluetec, who had single, female owner servicing it at dealer only. Car had poor 0-60 acceleration, but I gained 2 seconds by replacing air filters.
They are bear to replace on sedans, so those "keyboard technicians" don't want to get the fingers dirty.
Still my engine did not suck excessive oil.
On my GL350 the air filters are kind of a pain no doubt. Requires removal of strut tower brace and a bit of cussing to get the 2 airboxes snapped back in place when assembling. It requires torx , sockets ; wrenches and is definately not easy to just check. I got washable K/N filters and will clean and oil when doing oil changes.
With basically no blowby at all but was going thru oil at about a quart to 100 or 200 mile rate. Oil usage is less with the new air filters but still quite heavy. Turbo shaft play in and out is just a few thousandths which is fine and side to side is normal. Since the dpf is clogged quite a bit I am doing a delete pipe and tune as we speak and hopefully with less pressure beteen turbo and DPF it will lessen oil usage , if it is indeed pushing oil past the turbo seal. My hopes anyway for a cure.
FWIW....
The PCV valve and hose in the photo is the old design, was re-designed as it leak oil and the red seal would deteriorate and get sucked into the turbo charger - this is going to be very expensive.
Photo of new PCV assembly
The new PCV assembly is part number 6420101891, notice the new seal design to prevent the turbo charger from sucking in the old seal design. Also read they changed the internal diaphragm material to make it more resistant to oil and seal better. If the PCV is leaking oil it would be best to change the assembly.
The PCV valve and hose in the photo is the old design, was re-designed as it leak oil and the red seal would deteriorate and get sucked into the turbo charger - this is going to be very expensive.
Photo of new PCV assembly
The new PCV assembly is part number 6420101891, notice the new seal design to prevent the turbo charger from sucking in the old seal design. Also read they changed the internal diaphragm material to make it more resistant to oil and seal better. If the PCV is leaking oil it would be best to change the assembly.
01-14-2020, 06:55 AM
