Quote:
Originally Posted by Dark5yde
Well after the pressure test on the coolant system there was no leak. Same goes for the cylinder test. Did and oil change and the oil actually looked really good, not milky. He did the remove the oil cap while running test and the idle did not change. So his thought is that the CV system is plugged or blocked and that is causing the white residue on the cap and dipstick.
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The thought process here is incorrect, as the cause and the effect are being confused.
A plugged crankcase ventilation system does not cause moisture in the oil. It is the other way around. Moisture in the crankcase (naturally occuring condensation from heating/cooling cycles) mixes with the oil and leads to a build up of condensate (a white paste) and that can collect in the crankcase ventilation system, causing subsequent problems.
Neither of the above causes a loss of coolant, which is what you reported you were experiencing.
While the buildup of moisture is largely from condensation, you could have a coolant leak contributing to it, but that has not been determined yet.
The paste is usually at the top of the engine, under the fill cap. It can also collect in the CCV system. That isn't usually a problem until it gets cold enough out to freeze it. The paste can clog the CCV, but the usual failure mode is when it freezes (it freezes because it has water in it). When it freezes, the CCV can be stuck in one of two positions. If it is stuck closed (or blocked by the paste) then the engine crankcase becomes pressurized, and eventually blows out through the weakest point, often a valve cover gasket. If it is stuck open, then high vacuum from the crankcase (which happens on throttle over run, ie lifting your foot at medium to high rpm) can draw oil from the sump, through the CCV, and into the intake stream. That isn't a vacuum leak, it is a vacuum powered siphon.
If any of the vacuum hoses are shot, then you can have a vacuum leak.
When you think about vacuum, you need to separate the different zones inside the engine. The engine crankcase does not normally have a vacuum, it is close to zero pressure differential. The oil filler cap leads to the crankcase. A separate zone is the intake system, from the air filter through to the intake valve to the combustion chamber. That is where there is vacuum. You can't access that system through the oil filler cap.