Harbi

Urgent - Gray smoke
Greeting !
i have Mercedes W221 S600 V12 with some problem which is :


1- gray smoke induction from tailpipe .
2- this gray smoke not appeared in cold start
3- this gray smoke not appeared while accelerating.
4-this gray smoke not appeared in Idle " even if the car kept running for 2 hrs, no smoke"
5- this gray smoke just appeared when intend to stop in traffic light or when i slow down to for turning left or right
6- this gray is not continous. just big blow off for couple of seconds and then disappear.
7- this gray smoke is comming from only one side (driver side tailpipe)






Actions done till now:


1- on the first time, found some yogurt in the engine cooling water tank. it is white yogurt with red oil which indicates that it is from tranny oil cooler. So, replaced engine cooling radiator, tranny oil cooler and water tank as well since it is soo contaminated. -----------> no improvement


2- replaced biturbo cooling water electrical pump which found damaged. -------> no improvement


3- changed all spark plugs ----> no improvement


4- i ask the tchnician to check transmission vacuum modelator valve and his answer was " in w221 cars, there is no transmission vacuum modelator valve "


5- turbo of driver side has been checked by disconnecting the upper hose from engine side and found some oil inside.


6- my technician told me that there is a pressure build up in the the engine lead to oil escape through the turbo and the problem is not from turbo sealing.


7- my technician told me that the pressure issue is from the piston rings.


8- i'm suspect of his diagnosis and my question is :


-- does PCV valve make this issue of gray smoke ? if yes, where is the PCV valve on v12 engines M275 ?
-- in my car w221 s600, is there a transmission vacuum modelator valve? if yes , where



i need your usual cooperation to guide me to the right diagnosis


thanks in advance

alx

Question is- what fluid is your car using up? Oil? Coolant? It is most likely not tranny fluid despite its appearance.

My guess is your engine has overheated in the past and now you have a cracked/ warped head and you are using coolant. The v12tt motor runs very hot by default and your weather and broken ic pump only made things worse.
It is consistent with your symptoms on blowing puffs of smoke when slowing down as well as mixing oil and coolant.

Btw, having some oil in the turbo inlets is ok...

Harbi

Appreciated your thought and ur positive participation

My car got overheated last year due to cooling fan failure.

But for your kind information, yoghurt found in the coolant tank was surrounded by red oil ... and the only red fluid in my car is tranny oil .. is there any possibility for engine oil to be red colored in this case?

syljua

Yes, and you said you fixed that problem by replacing the radiator(s) and
it has not come back. So lets leave the red oil out of the question.

Now, even though you might have an leak of coolant into cylinders/oil,
does not mean that you have a leak of engine oil into the coolant.

But, if its actually a leak of coolant into cylinder, then most likely,
the cylinder action is also pressurizing the coolant system. Do you
have any symptoms of smoke in the coolant?

For coolant into oil, do you have any white buildup in the oil
on the affected side (the head)?

As of piston rings or not, I think the best indication
would be to find out if the smoke contains oil or not.

(Well, all in all, I'm just a desk mechanic, so take might suggestions
for what its worth...)
http://repairpal.com/what-does-the-s...tail-pipe-mean

br,
syljua

Harbi

the answer is : NO. i have checked the engine oil cap and looked inside the engine. no symptoms of any white color





for your update, radiator has been replaced last month and yesterday i've that coolant level alaram presented in the dashboard. when i checked the level, i found it lower than before and the water in not clear (light oily gray) but not yogurt .
i convinced my self that coolant is not clear due to remaining old oil mixed issue. on the other hand, big question formed in my head " why the coolant level get dropped down?"


do you recommended for me to use "Head Gasket & Cooling Sealant fluids" as a trial?

Harbi

please find below attached . what is the highlighted part using for ? and can this pars cause smoke from tailpipe when this part damaged ?

syljua

But you said that the smoke is only from the drivers side.
I think you're left hand drive in Dubai? If so, coolant in oil would
manifest itself inside the cylinder bank on the driver side.
The oil cap is on the passenger side (bank) of the engine.
I understand its more difficult to check the drivers side, and
I guess its not strictly needed, as it seems like you confirm that
you're loosing coolant below.

Its because, somehow, coolant leaks into your cylinders, and gets
to be a part of the combustion, leading to grey smoke.

That leak of coolant into the cylinder, is most probably because you
have a leaking head gasket.

No, I would not recommend using some magic sealing fluid, as it will most
probably just contaminate the whole coolant circuit.

br,
syljua

syljua

The part shown, is the pressure regulator for the
centrifugal oil separator (removing oil fumes from the crank case air).

If not working, I think it would "inject" air with excessive oil vapor
in it into the turbo, but that would be blue/black smoke.

Read more about the M275 (well, really the Maybach M285, but they are ~ equal) here;
https://web.archive.org/web/20060110...2008-06-03.pdf

In that same presentation, you will also see some of the things
they did to the divider between cylinders to allow coolant to flow.
And as you can see, the distance between some of the coolant passages
and the cylinder is not great, giving the gasket a pretty though job to
keep them separated...

br,
syljua

Harbi

Really appreciated your efforts and cooperation.


which method is more garanteed . overhaul the current engine or swap with used low milage one ??

DaveW68

If the overhaul is done right by somebody who knows what they're doing, it would obviously make more sense than buying a lower mileage engine where you have no clue what you're getting....especially if money were even or close to it.

Polar Bear

The only time I have noted a fuel smell and smoke was when I start the car to move it a short distance and turn it off for several hours. When it is started, say 5 hours later, it will smoke litely and smell very right, but it goes away get soon. I use the recommended Motor 1 Oil and recommended changes.

Nuru

Definitely +1