Some districts seem to have more than their fair share of people named Koos Wessels. Our town is one of those, so the locals invent nicknames to differentiate between each Koos. The most colourful ones in this subculture have names such as Rooi Koos (ruddy-faced), Geel Koos (Canola farmer), Groen Koos (non-polluting), and so on.
Our concern is with Geel Koos, who is named after the bright-yellow canola flowers on his farm. His petrol-engined Toyota Hilux started to smoke and lose power at just over 205 000 km, so we were asked to investigate. We last serviced it at 195 000 km and could not believe that the engine was worn out.
It showed some of the signs of a worn engine. When the dipstick was removed from the running engine, oily vapour poured out and the spark plugs had an oily coating. Syd was given the job and, during tea, he kept wondering what else could cause these symptoms.
As soon as his cup was empty, he walked to the car and put his hand on the problem.
He suspected a blocked PCV (positive crankcase ventilation) valve. He started the engine, pinched the hose next to the valve and strained his senses to detect the click that would show whether it had closed-up or not. There was no sign of life and so the valve was removed and cleaned.
We also ordered a new valve to fit at the first opportunity. The spark plugs were cleaned, as well as the oil and oil filter changed because the lack of breathing would have contaminated the oil.
The PCV valve is mounted on the camshaft cover and connected to the intake manifold by a hose. When the engine is off, the valve is springloaded towards the closed position. When the engine runs, manifold vacuums control the valve opening in such a way that the amount of blowby gas entering the intake manifold is proportional to the throttle opening. In this way the space above the oil is kept free of vapour and the crankcase pressure is kept low.
