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vicsterdog · Jun 10, 2009, 02:51 PM

I am looking for a very cheap used car and came across a 1990 Buick with 97,000 miles on it. The engine is a 2.5L 4cyl. The asking price is $800. I drove the car and everything seems fine. However, when I looked under the hood, I removed the air cleaner lid. That is where my problem comes in. The air filter was missing, the breather filter was clogged with oil, and there was a small amount of engine oil laying in the air cleaner. What would cause this? What kind of fix would be needed? Simple problem or should I walk away from the car. Thanks for your help, I do appreciate it.

anthony_moore09 · Jun 10, 2009, 03:29 PM

You can take some carbruator cleaner and while car is running spray in carb at least half the can then replace new air filter and car should be fine that normally happens when car just isn't taken care of but not a major issue.hope that helps!

RickMN · Jun 10, 2009, 09:23 PM

Sorry Anthony, I have to disagree with you. Oil in the air filter compartment can be a symptom of a plugged PCV valve OR evidence of excessive BLOW-BY. Blow by is when combustion gasses seep past the piston rings and into the crankcase. Blow-by happens in all engines--even new ones. In the old days, before pollution controls, car makers would just vent those gasses to the atmosphere. But when emission controls were put in, car makers routed a tube from the valve cover into the intake manifold and sucked the gasses back into the combustion chambers for a second chance. They installed another tube from the air cleaner to the valve cover to allow fresh filtered air to replace the gasses. To prevent a backfire from sending fire into the crankcase, they added a check valve called the PCV--Positive Crankcase Ventilation. The valve allows gasses to flow from the crankcase to the intake, but not the other way. If the valve gets clogged, pressure builds inside the crankcase and the gasses get pushed INTO the air cleaner box. Because of the pressure buildup, a clogged PCV valve can also cause oil leaks at the valve covers and oil pan. Those gasket weren't made to be under that kind of pressure.

In a severely worn engine, the gasses not only seep past the piston rings, but take oil along with it. All that oil ends up in the air filter box.

The fact that the air cleaner was missing is a sign that it was getting clogged with oil. Why else would an owner remove an air filter? The fact that he was driving it without a filter is enough reason to walk away from this car.

This may all turn out to be a bad PCV valve, but without further checking, I'd walk.

vicsterdog · Jun 11, 2009, 09:36 AM

RickMN... thanks for the answer/help. I appreciate it. Quick question, when I started the car and drove it, there was no visible smoke coming from the tailpipe. Would that give any clue as to whether it is blowby or a PCV. Thanks.

RickMN · Jun 11, 2009, 09:54 AM

If the catalytic converter was warm before you started it up, it would burn off any excess oil coming out the exhaust. Best way to check for a bad PCV is to remove it and shake it. If you feel the plunger moving back and forth and it makes a definite metallic clicking sound, it's good. If the sound is mushy or the plunger moves slowly, it's crudded up with oil deposits.