Gasoline
The PCV system includes 2 hoses and a PCV valve. Crankcase vapors are normally drawn from valve cover through PCV valve and into intake manifold. A hose from the air cleaner to the valve cover supplies fresh air to the crankcase.
When intake manifold vacuum drops due to heavy loads, the amount of blow-by exceeds the capacity of the PCV valve. Air then flows directly from the valve cover into the air cleaner and carburetor. When engine is not running, the PCV valve is closed and vapors are stored in the crankcase.
Diesel
The crankcase ventilation system on diesel engines consists of a breather hose connecting an upper chamber in valve cover with air intake. Oil baffle plates are located in upper chamber of valve cover. Blow-by gases are fed into the air intake and prevented from entering the atmosphere. Servicing is limited to keeping breather hose and passages free of obstructions.
Crankcase Ventilation System (626) Note direction of flow. Scheme 1
ROTARY ENGINE MODELS
The crankcase ventilation system on the rotary engine (RX7) is an integral part of the fuel evaporation system. A vacuum operated purge valve directs crankcase, fuel tank, and canister vapors into intake manifold when the throttle is opened.
Crankcase Ventilation System (B2200 Diesel Pickup). Scheme 2
MAINTENANCE
Check PCV system operation every 30,000 miles or 30 months.
GLC
Remove PCV valve. Blow through valve with mouth pressure from valve cover side of valve. Air should pass through. Blow through valve from opposite end. Air should not pass through. If valve does not operate as described, replace valve.
626
With engine idling at normal operating temperature, remove PCV valve from valve cover. Close off valve opening with finger and check that idle speed drops. If idle speed does not drop, replace valve. (Scheme 3)
Testing PCV Valve (626) PCV valve is connected to ventilation hose. Scheme 3
B2000
With engine at normal operating temperature and key off, remove hose from PCV valve. Run engine at idle and place finger over the PCV valve inlet. If idle speed does not drop, replace PCV valve.
Note. To replace PCV valve on California models with automatic transmissions and on all Federal models, first remove carburetor. Carburetor removal is not necessary on other B2000 models.
- Disconnect purge valve-to-oil filler tube hose from purge valve. Start engine and run at idle speed. Place finger over open purge valve port and feel that no vacuum is present. (Scheme 4)
- Increase engine speed to 2000 RPM and feel that vacuum is present at purge valve port. If valve does not operate as outlined, replace purge valve.
