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#161
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#162
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I don't understand your comment about the piston rings, can you explain?
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2007 X3 3.0si, 6 MT, Premium, White Retired: 2008 535i, 6 MT, M Sport, Premium, Space Grey 2003 X5 3.0 Steptronic, Premium, Titanium Silver 2002 325xi 5 MT, Steel Grey 2004 Z4 3.0 Premium, Sport, SMG, Maldives Blue |
#163
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The engine's alsways producing some big amounts of water because of combustion - no matter whether the engine's cold or warm. The oil molecules are like 10-15 times bigger and heavier, than water molecules - so the first moleculs will penetrate into crank case will be the water molecules for sure. So even there's no oil loses and dark smoke from the exhaust, the combustion water will get in to the crank case through the piston rings earlier. So if you see some water/oil sludge on your oil cap - the engine wasn't warmed up properly and/or was used for short trips only. |
#164
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Earlier you said the problem with the CCV was due to the piston rings, which I couldn't understand. Now you have said the rings wear as a consequence of moisture in the oil. Those are two different things. It is either cause or effect. I am not sure if you mean compression rings or oil control rings. I have had condensate form due to short trips, with no oil consumption. If the rings were wearing out, the first signs would be low or variable compression, or higher oil consumption. Absent those symptoms, I think the piston rings are fine. If you are saying that moisture in the combustion chamber doesn't go out the exhaust, but instead hangs around and permeates the block and migrates to the oil sump, then I don't agree. If water could permeate the block under those circumstances, then the cooling system would continually siphon into the sump. Obviously it doesn't. The combustion chamber is hot. It is the moisture in the crankcase that is a problem (and particularly under the valve cover), not in the combustion chamber.
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2007 X3 3.0si, 6 MT, Premium, White Retired: 2008 535i, 6 MT, M Sport, Premium, Space Grey 2003 X5 3.0 Steptronic, Premium, Titanium Silver 2002 325xi 5 MT, Steel Grey 2004 Z4 3.0 Premium, Sport, SMG, Maldives Blue |
#165
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The combustion water doesn't hang around it penetrates through both piston rings in to the crank case during the expansion phase like all other sump gases causing the pressure in crank case.
The weraing out piston rings causes penetration of combustion water, before you can discover any standard symptoms of bad piston rings, like you described. |
#166
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OK, I get what you are saying. I would agree that piston rings can have blow-by, which contains moisture. But since the moisture under the valve cover happens on brand new engines, irrespective of the condition of the piston rings, I don't think it is due to ring wear.
The problem under discussion is moisture under the valve cover. This moisture is widely accepted to be condensation, on the inside of the upper surface of the engine, due to repeated heating and cooling cycles. Those heating and cooling cycles are starting the car every day or so, and then parking it overnight in a cool environment.
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2007 X3 3.0si, 6 MT, Premium, White Retired: 2008 535i, 6 MT, M Sport, Premium, Space Grey 2003 X5 3.0 Steptronic, Premium, Titanium Silver 2002 325xi 5 MT, Steel Grey 2004 Z4 3.0 Premium, Sport, SMG, Maldives Blue Last edited by JCL; 01-27-2013 at 08:15 PM. |
#167
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The combustion water builds an emulsion with oil which gets under the valve cover vie regular oil circulation.
Maybe I still don't get you but what's the source of moisture in oil exept for the combustion, because condensation isn't a source, it's just a physical process. And normally theres no as much moisture in the crank case just because of atmospheric moisture. |
#168
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The combustion water builds an emulsion with oil which gets under the valve cover via regular oil circulation.
Maybe I still don't get you but what's the source of moisture in oil exept for the combustion, because condensation isn't a source, it's just a physical process. And normally theres no as much moisture in the crank case just because of atmospheric moisture. |
#169
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I agree that blow-by is one source of moisture. Atmospheric moisture is a second source. Intake air. Would be interesting to know the % contribution of each.
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2007 X3 3.0si, 6 MT, Premium, White Retired: 2008 535i, 6 MT, M Sport, Premium, Space Grey 2003 X5 3.0 Steptronic, Premium, Titanium Silver 2002 325xi 5 MT, Steel Grey 2004 Z4 3.0 Premium, Sport, SMG, Maldives Blue |
#170
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One thing that has crossed my mind several times is whether some kind of desiccant would work to pull the moisture out. I've seen desiccant breathers used on industrial machinery before, but have never heard of them being used on automobile engines. Something like that would really make a lot of sense in these machines. It probably wouldn't have been a cheap retrofit, but I wonder how much expense went into the warranty service that was done on these cars over the years, and how much of that cost could've been avoided.
Desiccant Breather Filters Maximize Equipment Life I know the mantra for some is that these cars are designed to be driven at operating temperature for a certain period of time to burn off the condensation, but the reality is that for many of us, that just doesn't happen. Try to tell my wife that she has drive an extra 20 miles to drive to work, which is less than a mile away... (she usually walks, but not when there's freezing rain to deal with, like the last few days.) Plus, when we live in the central part of a city where you can drive from one edge to another in 15 minutes, short trips are the rule, not the exception.
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2001 X5 Sport 3.0/5-speed 1998 318ti/5-speed 1988 735i/5-speed 1984 528e/5-speed (soon to be M20B25-powered 525i!) |
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