View Full Version : PCV VALVES

24-10-03, 03:30 PM
I have been reading about pcv valves a lot lately. Can someone tell me their purpose and advantage? I have been running a 3.5 for 4 years and have rocker box breather pipe connected to underside of carb.air intake housing.


24-10-03, 04:46 PM
Positive Crankcase Ventilation Valves allow the engine to be ventilated by clean air to prevent buildup of sludge, help with emissions etc. Usually there is an air inlet on one rocker cover - a housing with gause type filter in it - and a one way valve on the other. The one way valve is connected to the engine side of the carb/butterfly (vac side). This valve opens under high vac when the throttle is closed at idle to allow engine breathing by pulling air through the engine.Connecting the rocker cover breather to the filter housing is, I think, incorrect for PCV as there is no effective vaccum at this point as the butterfly is closed and your on the atmospheroic side of the carb. Hope this helps.

24-10-03, 11:00 PM
Run a forum search on pcv valves - we've all asked similar questions, and the subject has many useful posts.