1st Gen FTW - It's AutoMedic!
Join Date: Jun 2008
Location: Garrison, ND
Ok - So - I think we need a lesson on where crank case moisture comes from...
Your car starts out the morning cold. You get in it, and you drive. The engine gets warm. As the engine gets warm, the air inside the engine ALSO gets warm and expands (remember this, important). Air inside the engine is drawn out through the PCV system, and burned through the combustion process, and make-up air is then drawn into the crankcase via the intake manifold breather port. Generally, in a V6 engine, one port is on one side, and the other port is on the other side - so in the Intrepid (first gen at least) the PCV draws air from the engine on the driver's side, and air enters the engine from the air cleaner system on the passenger side.
The whole time you drive, this system happily breaths fresh air into your engine. Your engine gets hot like it should, and after some minutes of driving (20 or more or so), the engine has reached a high enough temperature for long enough, that any moisture inside the engine has boiled out... it has evaporated out of the oil, off the bottom of the oil pan, off the walls of the crank case, out of the lifter valley, and out of the valve cover cavities.
Happy system, Right?
Well, what happens when you park the car? The engine, naturally, gets cool. Remember that nice hot engine with all of that expanded air - well, when it cools, that engine air contracts. The engine does a big INHALE as it cools. The air that it draws in is drawn in through the air filter assembly, to make up for the volume of air that has contracted.
In the summer time, dew collects on the grass, your windows may have dew on them, your car glistens in the beauty of the sunrise... And in the wintertime, we get a nice layer of frost on our windows and when it is really foggy, and really cold, we get a nice layer of hora frost on the trees, and we step out and shiver while we say "Wow, what a pretty morning."
And just like the paint glistens, and just like the frost grows on the trees - like wise with the insides of our engines. Water condenses out of the air, and precipitates out as dew or frost on the inside of the engine. Remember, it breathed in all that air over night as it cooled down...
So - we get back in the car, and we drive. The engine heats up, etc etc etc. Lather, rinse, repeat.
Ah yes, there is a but...
IF your PCV system doesn't work properly... The engine will heat up, the water will evaporate from inside the engine, but it won't be drawn out actively by the engine. It will be allowed to float out (as the OP discovered), or it will just stay in there and you never boil off the moisture. HELLO SLUDGE!
OR - if you don't drive your car long enough... the water will get warm, but won't boil out of the oil/crank case. HELLO SLUDGE! Both conditions will provide you with milky oil and a breakdown of the system as designed.
In a 2.7 engine with an internally mounted water pump - or in any engine with a mild head gasket leak - the problem is just that much worse because of the already natural uphill battle.