General Motors 4.3L GM Engine — Crankcase Ventilation System Functional Check
Testing & diagnosis · PCV system
For the General Motors 4.3L GM Engine, from the General Motors service manual.
Before you start
- A plugged PCV orifice/hose may cause rough or unstable idle, stalling, oil leaks, oil in the air cleaner, or sludge; a leaking PCV may cause rough idle, stalling, or high idle.
Procedure
- Remove the PCV hose from the rocker arm cover.
- Operate the engine at idle.
- Place thumb over the end of the hose to check for vacuum; if no vacuum, inspect for plugged hoses and/or clogged or damaged manifold vacuum port.
- Turn the engine OFF.
- Inspect the PCV orifice in the valve cover for debris or blockage; clean with carburetor cleaner as necessary.
Tools required
- Carburetor cleaner Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Source: General Motors 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.