A journey into the the infamous Om642 oil cooler leak! - Page 6 - PeachParts Mercedes-Benz Forum

iwrock · #76 12-04-2016, 01:25 PM

Decided to farm this one out...

A friend is hooking me up on the labor - he's done a few dozen of these seal replacements, so it's no sweat for him. $350 for labor+parts... Looks to be somewhere in the neighborhood of $600-700, parts are going to be ~$225, plus the cost of hot tanking all of the parts so they're clean.

phlfly · #77 01-10-2017, 10:34 PM

Hello,

I got 09'ML320 Bluetec.
It has small leak as you can see oil on alternator. There is no oil on bell housing or any oil at rear at engine. Took down engine underneath plate, and saw that oil is leaking along EGR pipe at it lower part (looking at engine).
Do you have ideas what is gasket failed. I look at top, but it doesn't look bad I meant there is some oil spots but nothing major.

Please help with ideas.

phlfly · #78 01-10-2017, 10:55 PM

Also I found connector that doesn't have anywhere to connect ?
Its right near thermostat.

https://flic.kr/p/PTnaKa

jay_bob · #79 01-11-2017, 06:57 AM

I would say if the rear of the engine is dry then it is most likely not the oil cooler seals in your case. If you look back at the photos of the removed cooler you will see a weep hole in the rear of the cooler well. That weep hole drains the leaking oil out to the ground by the bell housing.

However if you are getting oil leaks in the front out of the mixing chamber, I would suspect that you have excess blow by gettting into the charge air stream. The air path on this engine is:
Air filters -> Y-pipe -> Turbo -> intercooler -> mixing chamber -> manifold

The crankcase ventilation "puck" is on the lower right side of the engine, it is piped up to a fitting at the neck of the Y-pipe that goes right into the turbo inlet.

The EGR gases are taken from the exhaust manifold at the rear, pass through the EGR valve, through an air to coolant heat exchanger "EGR cooler" tucked under the intake manifold, to the front of the engine. The EGR gases are introduced into the charge air stream in this mixing chamber.

Some thoughts:
- clogged air filters can increase the amount of blow by sucked through the crankcase ventilation, the result is this fills up the charge air system with excess blow by oil. There is a differential pressure sensor on the left side filter, if the filters are clogged, it's supposed to trigger a warning.
- a ruptured diaphragm in the crankcase ventilation puck would be suspect if you have excess oil in the charge air system.

Fortunately it does not require pulling the manifolds to remove the mixing chamber or the crankcase ventilation puck.

I would start with taking off the Y-pipe and see how much oil is getting pushed into the turbo inlet.

Next I would remove the mixing chamber from the front of the engine and see if it you can tell where the leaking oil is coming from.

I think the fix is going to involve a bad gasket or o-ring on the mixing chamber but the root cause may end up being the crankcase ventilation puck.

phlfly · #80 01-11-2017, 08:22 AM

Thank you I will check and let you know what is problem.

jay_bob · #81 01-11-2017, 12:28 PM

Quote:

Originally Posted by phlfly

Also I found connector that doesn't have anywhere to connect ?
Its right near thermostat.

https://flic.kr/p/PTnaKa

That's not good, surprised you are not throwing a code for that. When my wife gets home I will have a look and see what that is supposed to connect with.

Edit: Have a look at the linked photo in post 56 of this thread.
Directly behind the fuel filter (at 1-o'clock, right above the steel high pressure line) you will see a connector that is hanging out. Directly below this connector is the socket on the swirl flap motor. This motor drives flaps in the intake manifold that change the geometry.
I bet if you look up in your connector you will find a 4.7 k ohm resistor stuck between the two center pins. That is the bootleg bypass trick if this motor fails, to fool the computer that the motor is still there. Reason I know this is that it happened to me, my motor blew and I did the resistor trick until I could get time to fix the car. Otherwise the ECU sets a code and the car cannot make 45 mph.

Changing this motor involves removal of the turbo, fuel filter, and wire harness to get to the motor. It is right below the plastic wire harness protector that is sitting under the turbo. You might as well go ahead and do the full oil cooler seal job, you are more than half way there to the seals and it is a matter of when, not if, they will leak. If you get the OM 642 oil seal kit from f c p euro dot com this will give you a new swirl flap motor, new crankcase puck, and all the seals and gaskets and single use bolts you will need to get the job done.

phlfly · #82 01-11-2017, 01:31 PM

Do you mean one circle red or yellow.
I looked at my connector as one in my picture and i don't see anything inside as just pins. My connector right near thermostat.

Thanks

Quote:

Originally Posted by jay_bob

That's not good, surprised you are not throwing a code for that. When my wife gets home I will have a look and see what that is supposed to connect with.

Edit: Have a look at the linked photo in post 56 of this thread.
Directly behind the fuel filter (at 1-o'clock, right above the steel high pressure line) you will see a connector that is hanging out. Directly below this connector is the socket on the swirl flap motor. This motor drives flaps in the intake manifold that change the geometry.
I bet if you look up in your connector you will find a 4.7 k ohm resistor stuck between the two center pins. That is the bootleg bypass trick if this motor fails, to fool the computer that the motor is still there. Reason I know this is that it happened to me, my motor blew and I did the resistor trick until I could get time to fix the car. Otherwise the ECU sets a code and the car cannot make 45 mph.

Changing this motor involves removal of the turbo, fuel filter, and wire harness to get to the motor. It is right below the plastic wire harness protector that is sitting under the turbo. You might as well go ahead and do the full oil cooler seal job, you are more than half way there to the seals and it is a matter of when, not if, they will leak. If you get the OM 642 oil seal kit from f c p euro dot com this will give you a new swirl flap motor, new crankcase puck, and all the seals and gaskets and single use bolts you will need to get the job done.

jay_bob · #83 01-11-2017, 02:15 PM

My guess is your loose connector is the one circled in red. That is the one that goes to the swirl flapper motor. The socket for the swirl flap motor is right below the plug, it is the oval on top of the black shiny object directly behind the fuel filter and below the wire harness trunk cover.

The one you circled in yellow, its harness tail is too short to come over to the fuel filter as shown in the picture of your car. That is the MAP sensor and it is still plugged into the right intake manifold in my picture.

Another clue is there are several flavors of connector on the engine. Some are the type with the two wings on the side and others with the gray push button. Your loose connector is a gray push button type with 3 wires.

Process of elimination:

It can't be the mass airflow sensors on the Y-pipe, those are side wing style
It can't be the PCV valve, that is a gray button type but it is a 2 wire, it is hanging in the air over the PCV valve in my photo
Your water in fuel sensor is plugged in on your car, it's a gray button type but it's a 2 wire.
The turbo VNT actuator has like 5 or 6 wires and it is a side wing type (in my photo, it is right behind the PCV valve).
The injectors use the gray button connector but if one of those were to be unplugged you would certainly know it.

The only thing left in that area from the best of my memory is the swirl flap motor. It does have a rather long tail and it is capable of being routed out from the main harness trunk and laid out by the thermostat/fuel filter. It also has the gray button release.

phlfly · #84 01-11-2017, 02:21 PM

I would not be lazy, gone to my car and get p/n off the plug connector ( A023545532). It's 3 pin connector, than search and guess what is that?
It's for the fuel filter heater element. It's even thread on other forum.

What is plug A0235455326 for? - Mercedes-Benz Forum

It said it might be 09's were not equip with heater for the USA configuration

Thanks jay_bob

jay_bob · #85 01-11-2017, 03:38 PM

The 08 did not have that connector so thus my confusion. No left over connectors when I put my engine back together and the 08 does not have a heated fuel filter.

Wife just got home so I was on my way to go look under the hood and decided to check here first.

In that case then my original theory of excess blow by leaking out the mixing chamber stands.

phlfly · #86 01-11-2017, 09:41 PM

So if I'm right understand you think:
1. It might Air filter clogged, so the turbo sucked all air/oil from engine. Then its end up in EGT pipe, that is brining oil to mixing chamber.
2. PCV system is crap out and might needs replacement.

So I will check my filter tomorrow.
But my question is do I need to replace mixing chamber, or any seal on PCV, if we are assuming filters are crap.

Thanks

Quote:

Originally Posted by jay_bob

The 08 did not have that connector so thus my confusion. No left over connectors when I put my engine back together and the 08 does not have a heated fuel filter.

Wife just got home so I was on my way to go look under the hood and decided to check here first.

In that case then my original theory of excess blow by leaking out the mixing chamber stands.

jay_bob · #87 01-12-2017, 07:16 AM

The PCV puck is down on the right side of the engine. It has 2 or 3 bolts and is easy to get to once the right side air filter box is removed.

The mixing chamber itself is probably not faulty. You probably will need to replace the associated gaskets and o-rings that connect it with the intake and EGR tubes. If I recall correctly the intercooler line plugs and clips into this chamber, with an o-ring seal.

First thing I would do is remove the Y-pipe and see what the inside of the turbo looks like.

You can also check the inside of the PCV valve tube and see how oily it is. Unplug it first, the metal collar inside the PCV valve sensor is energized and if it touches the engine it will blow the ECU fuse.

Next thing I would do is go to the front of the engine and detach the intercooler hose from the mixing chamber and check for oil there.

I wouldn't take the mixing chamber loose from the front of the engine until you have the replacement gaskets and o-rings in hand to re-seal it. When you do go forth removing the mixing chamber, keep close track of the bolts, there are 5 bolts I think, all of different lengths. Be sure to make notes on how it goes back together.

You might find it helpful to get a copy of the WIS + EPC from eBay. Especially since MB cut off public access to EPC without paying $75/year. EPC is the parts system the counter guys at the dealer use. WIS is the electronic factory manual.

phlfly · #88 01-12-2017, 01:59 PM

Is mixing chamber a part of throttle body. I'm trying understand where can oil leak from mixing chamber?

jay_bob · #89 01-12-2017, 02:19 PM

Note there is no "throttle body" on a diesel like on a gas engine. However there is a flap actuator in the mixing chamber to enhance the ability of the engine to suck the sooty EGR gases into the air stream (so it can make a nice carbon crusted mess in the intake manifold). Because the government thinks that's a good idea or something.

Ok back on topic.

There is no connection to the engine oil path in the mixing chamber. It is just bolted on the front of the engine. If oil is clearly leaking from the mixing chamber then it has to be getting there via the incoming air stream. The most likely points of oil to be introduced into the air stream are the PCV valve or the turbo.

My rant about the EGR got me thinking. It also may be just condensed EGR grunge seeping out through a bad seal or even possibly a crack in the mixing chamber (it's made of plastic). If the PCV pipe is (relatively) clean and there is not a ton of oil in the turbo after you take off the Y-pipe, then maybe it's just EGR goo seeping out.

Do the deposits on your alternator feel oily or sooty?

phlfly · #90 01-12-2017, 08:05 PM

ok, I have removed and replaced air filters and fuel filter. Air filter is little pain. I have removed sound proof panels. Also I found to hard time to install, filter box back, since it was hard to get box into rubber grommets.
I found these in the bad shape. It seems to me it was changed like few year ago or back it was under warranty.
Also PCV valve is all went and oil leaking even along edge of the engine.
When I have disconnected air intake from turbo it wasn't much oil inside, just small puddle. I have to more likely replace PCV valve assembly. I will order all assembly from FCP Euro.

Only I hard time to find p/n's gaskets for the mixing chamber. Can you give me p/n for the mixing chamber please.

See attached picture

Thanks