Your Most Important $2 Investment
On 1969 and later four-cylinder engines, the flame trap (a replacement for the old PCV valve in the "positive crankcase ventilation" system) prevents engine backfires from igniting in the crankcase. However, airborne contaminants and oil residue will eventually clog this device and cause excessive crankcase pressure. Symptoms of this problem may include finding your oil dipstick lifted up from its entry tube and worse, leaking engine seals. On B20 and B30 engines, the flame trap is located in the nipple atop the engine breather oil trap just forward of the distributor. On 1976 to late 1980 B21 engines, it is located inside a plastic "T" just to the left of the front of the cam cover above the thermostat. Unfortunately, beginning in late 1980, the flame trap is "buried" under the intake manifold. Do not let this discourage you. Replace the flame trap every year for trouble-free engine performance.

Also replace the hoses connected to it if they appear bloated or "spongy" from engine oil damage. Do not use clamps to hold flame trap hoses in place; if they are popping off, you may have excess crankcase pressure. Also check that the vacuum fitting on the induction (intake) mainfold is open and providing vacuum for the PCV system. The fitting is connected by a small hose to the flame trap housing.