See Figure 1
- Replace the crankcase ventilator regulator valve with a known good valve of identical design.
- Start the engine and compare idle conditions with the prior idle conditions. If engine idle is satisfactory (with the new valve installed) trouble exists in the old valve and it should be replaced.
- If loping or rough idle still persists with the good regulator valve in place, the trouble is elsewhere. Check the crankcase ventilator system for restriction at the intake manifold or carburetor spacer.
- If the system is not restricted, explore further the aspects of tune-up and the various elements of exhaust emission control.
Complete and detailed procedures for the servicing of the crankcase ventilation system are found in the Maintenance information of General Information And Maintenance .