Ford CSG-649 — Crankcase Ventilation System Functional Check
Testing & diagnosis · Positive closed-type crankcase ventilation
For the Ford CSG-649, from the Ford service manual.
Applies to: Ford CSG-649
Before you start
- Do not disconnect the crankcase ventilation system and make carburetor adjustments to compensate for a rough idle.
Procedure
- If the PCV valve rattles when shaken, reconnect it; if not, replace it.
- With the engine at idle, disconnect the hose from the air cleaner and feel for vacuum at the hose.
- Some vacuum indicates the system is OK.
- No vacuum indicates either the system is plugged or the valve is leaking.
- Install a known good regulator valve in the system and compare engine idle condition.
- If the rough idle remains, check the crankcase ventilation system for restriction at the intake manifold or carburetor spacer.
Full service-parts list: Ford CSG-649 →
Source: Ford service manual. Steps and values are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.