Originally Posted by eeeehaw (Post 6668029)

I have experienced two causes of oil leaks on this engine, and during the process of reading up on the topic across many forums have found other causes. Here's a summary that perhaps owners & DIYers will find useful:



(1) Most common cause is faulty/failed turbocharger air intake pipe seal. This is the black plastic pipe carrying air from the air cleaner box to the intake of the turbo. There is a smaller rubber hose-pipe plugged into the side of the turbo inlet end of this pipe that carrys crankcase blow-by vapors from the nearby Crank Case Ventilation (CCV) valve attached to the passenger side valve cover. When the engine oil is filled beyond rated capacity, which is approximately more than 2/3 of the way up the area between the 2 black plastic boundary indicators on the engine oil level measuring dipstick, the CCV will pass an excessive amount of oil vapor into the turbo inlet, and when that can cause 2 nasty problems: (1) on an older faulty design air intake pipe the orange seal will leak oil slowly out and onto the top of the engine, which can cause several problems including the one described in this thread; (2) the oil vapor condenses within the engine intake system and after entering the engine intake manifold will mix with exhaust soot coming from the Exhaust Gas Recirculator (EGR) valve creating a gummy substance that eventually impedes the proper flow of air into the cylinders, cakes up the insides of the manifold, and impedes the motion of the intake actuator vanes ("stir vanes") for each cylinder.

Solution to leaking air intake pipe seal: (1) Mercedes has an improved design replacement air intake pipe seal & pipe; the old one has an ORANGE colored rubber seal, you can check by easily removing the pipe and looking at the end that was attached to the turbo intake, and some have been reported to just push onto the turbo intake without a metal pipe clamp (not all, tho); the new replacement has a BLACK colored rubber seal, and a metal pipe clamp. Fortunately, this is a fast, easy, relatively inexpensive repair that many DIYers undertake or that should not cost a lot for a mechanic to do. (2) Some owners have added an after-market (non-MB) oil-air separator device between the CCV valve and the turbo air intake pipe to reduce or eliminate the crankcase oil vapor entering the engine, available from a wide variety of manufacturers including one in Germany to address this common problem with this engine; some (such as myself) built such a separator from inexpensive parts from a hardware store. I also chose to replace the CCV valve for good measure, and MB has an updated design for that part as well.


(2) Oil cooler gasket leak; this is the second most frequently reported cause. The engine oil cooler is bolted to the top of the engine block under the intake manifold, and it in turn is connected to both engine coolant and oil passages. It cools/warms engine oil to the temperature of the coolant as they both circulate through a heat exchanger. The heat exchange device ("cooler") itself rarely goes bad, but is apparently has happened via internal corrosion, typically by the introduction of the wrong type of coolant into the engine. The majority of problems are due to one or more seal gaskets eroding over time, allowing the oil, which is under high pump pressure, to leak out onto the top of the engine block and subsequently onto other engine electrical pipes and most notably the intake stir actuator motor and eventually causing failures of those other systems. I have read reports of severe failures of one or more of these gaskets resulting in 1-2 quarts of oil added to the engine every fuel tank refill, puddles of oil on the ground, oil over both the front and rear of the engine, oil all along the underside carriage, etc, and CEL/MEL OBDC codes of low oil pressure.


Solution: Replace the seal gaskets for the oil cooler heat exchanger. This is a relatively big job, with reports of typically minimum 8-12 hrs for a mechanic or DIYer to do, as it involved removing the turbo, intake manifold, and everything else immediately above them to gain access to the oil cooler. While the intake manifold is off, it should be thoroughly cleaned of any soot & oil buildup inside (I hear that diesel or carburetor cleaning fluid works well after a good soaking, compressed air blasting, etc). As noted above, some owners have opted to replace the relatively expensive oil cooler itself while the engine is apart for future peace of mind, especially if the engine has 150,000 miles on it, and the vane actuator ("stir") motor since it's also hard to get to when the engine is assembled and is prone to failures.


(3) Leaking turbocharger mounting bracket oil seals. The high-speed operation of the turbo shaft requires oil lubrication of its bearings to maintain long life, therefore the turbo is mounted on a vertical support bracket/shaft that contains passages for engine oil to be pumped up from the engine block to the turbo bearings. That support shaft has 2 gaskets, one that is between the support shaft and the top of the engine block and another between the top of the shaft and the turbo that is bolted onto it. Either of those gaskets erode, or the bolts securing the support shaft become loose from either the engine or the turbo, and oil can leak out onto the top rear of the engine, including the hot exhaust pipes attached to the turbo causing the burnt oil smell. Replacement of these gaskets is not terribly expensive, as the turbo and its support shaft are easily removed, and the gaskets are fairly inexpensive. I personally experienced this leak with my engine and was able to replace myself.


(4) Turbocharger bearing oil seal leak/failure. This is much less common, but has happened. This will leak oil onto the top of the engine IF you also have the older turbo air intake pipe with the orange seal (see #1 above). The high speed (10,000rpm or more is not uncommon I hear) turbo shaft is hard on its bearings and associated oil seals, and with high-pressure oil pumped from the engine bearing down on the seals you can imagine that something will eventually wear out. Fortunately, Garret and other modern turbochargers are designed to last a long time, but premature failures happen sometimes. When the turbo oil seal begins leaking slowly, there will be oil on the intake vanes that looks remarkably similar to what it looks like when the intake pipe seal or CCV valve fails (see #1 above) so it may be hard to definitively diagnose one from the other (since #1 is so much cheaper to do and much more common, it's worth proceeding with doing it first anyway, including replacing the CCV valve IMO). A failed turbo oil seal can cause that nasty gummy build-up inside the intake manifold, and oil accumulation in the resonator and intercooler at the front of the engine, so should be taken care of as soon as possible. New turbos are expensive, rebuilt ones are considered by many mechanics as being as good as new at 1/2-2/3 the price, but they're still expensive and will require a few hours work to replace. It's been advised to buy a turbo along with it's exhaust vane actuator motor (bolted together) as they are better calibrated by the supplier to work together, altho there is debate among engineers & mechanics about that since the engine control module (computer) is supposedly designed to "self calibrate".


BTW, failure of the intake vane actuator "stir" motor does not cause the vehicle to go into "limp mode" as it is an idle engine speed emission control ("stirs" the air entering the cylinders for better combustion for lower exhaust pollutants) that does not lead to catastrophic engine failure potential. As a simple comparison, the failure of the turbo exhaust vane actuator motor or its linkage will lead to limp mode, as it can cause dangerous over-boost intake air pressure for the cylinders; there are other causes of limp mode, but I have not heard anyone report the stir motor failure as one.

Originally Posted by Speyside (Post 7177946)

Thanks for the awesome summary, I had mine up and running in no time, leaking oil from the orange seal onto the wires caused the malfunction...

--Do you happen to know the new and improved part numbers for the:

Orange seal 642-094-00-80
CCV/ hockey puck/ Bleeder Valve 642-010-18-91?

I hope a new puck CCV design may help limit the flow of oil to the turbo entry. I will take a look at some oil separator designs too, sound like a great preventative fix.

---

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Originally Posted by jl553 (Post 5814600)

I got the following 10 codes on my car.



2527-2 check component Y27/9 (left EGR positioner)
3053-4 check component B2/7b1(intake air temperature sensor)
3052-4 check component B2/6b1 (intake air temperature sensor)
2603-4 check component B2/7 (Right hot film mass air flow sensor)
2602-4 check component B2/6 (left hot film mass air flow sensor).short circuit or open open circuit
2646-1 check component B2/6 (left hot film mass air flow sensor). Value is above limit.
2514-2 check component R39/1 (vent line heater element) short circuit to ground
2679-4 check component B76 (fuel filter water level sensor)
2526-2 test signal cable to component Y77/1 (charge pressure positioner) short circuit to ground
2530-2 check component M55 (Inlet port shutoff motor). short circuit to ground



Dealer says replacement of oil cooler,air intake manifold,etc and the bill is $2,900 + tax. My car is out of warranty and on an after-market warranty but the warranty company simply declined the repair request saying it is not covered. But what is the real problem here? Do I need to have the oil cooler replaced or just the oil motor? One tech even says it may be just the flaps are sealed,etc.



Any one can help here? Really appreciate it.

Originally Posted by rndproctor (Post 7862262)

Did you ever get a solution to this post?:

"I got the following 10 codes on my car.

2527-2 check component Y27/9 (left EGR positioner)
3053-4 check component B2/7b1(intake air temperature sensor)
3052-4 check component B2/6b1 (intake air temperature sensor)
2603-4 check component B2/7 (Right hot film mass air flow sensor)
2602-4 check component B2/6 (left hot film mass air flow sensor).short circuit or open open circuit
2646-1 check component B2/6 (left hot film mass air flow sensor). Value is above limit.
2514-2 check component R39/1 (vent line heater element) short circuit to ground
2679-4 check component B76 (fuel filter water level sensor)
2526-2 test signal cable to component Y77/1 (charge pressure positioner) short circuit to ground
2530-2 check component M55 (Inlet port shutoff motor). short circuit to ground"

I have the exact same codes on my 2008 ML320 CDI. Any help would be much appreciated. Thanks!

Originally Posted by 06e320cdi (Post 5818740)

I just found this from another post here. Sounds like your issue.

http://www.benzworld.org/forums/w164...ml#post5996393
I want to thank Sid and Skippy for this thread. http://www.benzworld.org/forums/imag...es/bowdown.gif
I had simmilar problem with my ML 320 CDI for couple of months now and the carhttp://images.intellitxt.com/ast/adTypes/icon1.png was in two shops with no luck. Yesterday i was able to find this thread and fix it my self.
The car could not accelerate and had around 10 different codes. The codes were pretty much for all of the sensors on the engine. If you try to erase them they were comming right back on. I went to "Mercedes Benz of Buckhead" in Atlanta and after paying $150 to diagnose the problem they told me that is problem with the harness and i need to pay another $850 to tell me what exactly is. I was told they needed to start dissambleing the front of the car to pin point the bad wires, but most likely i need new harness ($4,000-$5,000). Then i took the car to another service place and sat there for three weeks with no luck.
It turned out to be the problem Sid described. The seal on the turbo was broken and oil was leaking on top of that plug, which shorted and burned the fuse (#104 - 15 amp). I replaced the seal and the fuse and the car is running great once again. It only cost me $15 to fix it and the stealer wanted $5,000. Hopefully this will help others to determine their problem and fix it.http://www.benzworld.org/forums/imag...s/thumbsup.gif