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Posted By: nikothenomad Oil in Air Cleaner Housing - June 05th 2018 6:24 pm
Every once in a while we get a little something in the air cleaner housing. Usually it is fuel spray from flooding but this time when we pulled the top off there was a small puddle of oil in the bottom of it and the filter about 1/3 to 1/2 coated as well. Typically we replace our filter because it just seems like a good idea (meaning we rarely have much obvious dirt and our filters are still fairly white when we swap them out). This one is pretty darn solid black on one side now.

Anyway, from my reading, I've found that I should first check the pcv valve. Since it is a simple fix, I'll do that first. If that's o.k. I am under the impression that prior to doing an actual compression test I could look at the spark plugs to see if they are covered in oil (which they never have been since buying the van so we would know something is different).

Any other thoughts or ideas on how to check to see if this oil in the air filter housing was a fluke or something serious?

Posted By: Reed Re: Oil in Air Cleaner Housing - June 05th 2018 8:38 pm
Change the PCV, crankcase breather, and the air filter and see if the oil in the aircleaner comes back. Oil in the air cleaner is usually a symptom of (a) a bad PCV or (b) blowby. Blowby is worn out rings or cylinder bores. If changing the PCv doesn't fix the problem, it is time for a compression check or, better yet, a leak down test to determine the health of the engine block/rings.
Posted By: nikothenomad Re: Oil in Air Cleaner Housing - June 05th 2018 9:10 pm
Alright. That's what we were thinking, Reed. We'll do the tests before we go any further down the road since we are in a location that gives us opportunity to work on the van and access to a second vehicle. Would rather know than get caught on the road stranded. Would the leakdown test be a definitive?
Posted By: Reed Re: Oil in Air Cleaner Housing - June 05th 2018 10:41 pm
Yes. A leakdown test will absolutely tell you if the rings or cylinders have worn to the point of allowing excesive amounts of combustion gasses to leak past the rings and pressurize the crankcase, forcing oil into the PCV.
Posted By: nikothenomad Re: Oil in Air Cleaner Housing - June 05th 2018 11:02 pm
OK Then. That is the test we will do. Once we get the coolant system put back together! Thanks!
Posted By: nikothenomad Re: Oil in Air Cleaner Housing - June 06th 2018 12:19 pm
Reed, I think I was confused. What about the compression test where you put some oil in the spark plug hole? Different than a leak down test? What does it reveal?
Posted By: Reed Re: Oil in Air Cleaner Housing - June 06th 2018 3:40 pm
You were thinking of a compression test. A compression test just tells you how much compression any particular cylinder is making. This is useful, but not a good as a leakdown test. A leakdown test actually pressurizes each cylinder while you monitor the pressure and listen for leaks. If a leak is detected, you can pinpoint if it is leaking into the intake, exhaust, cooling passages, or crankcase. A leakdown test gives you much more and more accurate information than a simple compression test. See here: https://mobiloil.com/en/article/car-maintenance/car-maintenance-archive/how-to-do-a-leakdown-test
Posted By: nikothenomad Re: Oil in Air Cleaner Housing - June 06th 2018 8:34 pm
Yup. Sounds like leak down is the way to go. Although I may do a regular compression test to start out simply because I did one when I bought the van and a comparison of the numbers eight years later might be interesting.

Thanks! This will get done after we finish getting the coolant system back together.
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