A serious case of "blowby" means it's time for a new car, or at least a rebuilt engine.

Dear Car Talk

Dear Car Talk | May 01, 2004

Dear Tom and Ray:

I have a 1991 Ford Escort with a 1.9-liter engine. I have oil accumulating in the air cleaner, then draining out on the driveway. It appears that the oil is coming from the top of the valve-cover vent tube into the air box. I have changed the PCV valve (which is a different vacuum line out of the engine), with no success. It seems to only do it after driving at highway speeds for any distance. I also pulled the valve cover to replace the gasket and cleaned out the valve cover with a solvent. I even went to the extent of re-routing the valve-cover-to-air-box line "uphill" from the air box to try to eliminate the problem. The vehicle has 98,000 miles on it and runs fine; no other symptoms. Any ideas for me? -- Arthur

RAY: Ideas for you? Yeah. Start looking for a new car, Arthur. Or at least a rebuilt engine.

TOM: You've got a severe case of blowby. Blowby occurs when your piston rings get old and worn out. What happens is that combustion gases from the cylinders slip by the worn-out rings and end up down in the crankcase, where they don't belong.

RAY: The PCV (positive crankcase ventilation) system can take care of a certain amount of that excess combustion gas. But at some point, all that heat and pressure overwhelms the system, and the gases start pushing oil out of the engine. And the path of least resistance for the oil is through the breather hose to the air cleaner.

TOM: There are some "additive" products on the market that claim to help heal worn-out or sticky rings. You've got nothing to lose by trying them now.

RAY: We've had some success loosening sticky rings with a product called Restore. But you might as well try all of them. Try Smoke-Be-Gone, Heap-Be-Gone and if neither of those work, '91-Escort-Be-Gone.

TOM: Seriously, Arthur, if the car is otherwise in good shape, you can look for a junkyard or rebuilt engine. But since it's a '91 Escort with 98,000 miles on it, I don't think anybody would think less of you if you took this as your signal to dump this car and go for an upgrade. Good luck.

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