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Car Forum / Ford / Ford Falcon / September 2003One little PCV valve caused a lot of problems.
After 24 years of rattling away the PCV valve started to lose some of its sealing when the engine (351c) was idling. PCV valves are supposed to admit only a small amount of crankcase gases (mostly air if the engine is in good condition) when manifold vacuum is greatest ( idle and over-run). Once revs rise under acceleration the vac drops and the valve is pushed by its spring off its seat and allows much more crankcase ventilation to occur which is normal. This original equipment valve was letting too much air in at idle and would vary causing the engine to intermittantly:: miss at idle on LPG (LPG is airleak sensitive), cause the brake-booster to not top up vacuum sufficiently at idle causing lossof assistance in slow moving traffic once the resevoir had been depleted, introduced a partial miss on cylinders 4 and 8 at idle (this was a prime indication that the PCV valve was faullty), and make the car hard to start when cold. One tell-tale sign (apart from all the others) is the engine idling high especially on petrol and removing the PCV line from the engine while idling caused little change in idling speed/quality. A $16 replacement fixed ALL this! $%@#! Jason Errata: Last paragraph should read: once the PCV valve is removed from the rockercover and is sealed off with a rag, the idle would drop revs and smooth-out. The new valve caused little change in idle speed/quality when removed. Jason > After 24 years of rattling away the PCV valve started to lose some of its > sealing when the engine (351c) was idling. [quoted text clipped - 19 lines] > > Jason gotta love those cheap little fixes that make a world of difference > Errata: > [quoted text clipped - 32 lines] > > > > Jason > After 24 years of rattling away the PCV valve started to lose some of its > sealing when the engine (351c) was idling. [quoted text clipped - 19 lines] > > Jason Heh, a lesson there. Simple stuff first - but which simple thing is it causing the trouble:-) I wonder of the PCV Valve problem you experienced is the 'real' reason for horrible repeated crank-splutter-stall noises all over Aus on winter mornings. Add in the fact that the PCV Valve(s) spring(s) is(are) subject to an 'interesting' life, and shouldn't be expected to last indefinitely. So the matter of keeping them clean as well as replacing them at reasonable intervals should assist. Sort of like thermostats. Some will go the life of the engine, but we'd be nuts to operate on that premise.  SignatureToby quidquid latine dictum sit, altum viditur [...] > A $16 replacement fixed ALL this! $%@#! Yep; that can be a bastard to diagnose. (Dave thinks back to his old 1600 TC Cortina, where he almost stripped down the engine, looking for his idling problem.) -- Dave > [...] > > A $16 replacement fixed ALL this! $%@#! [quoted text clipped - 5 lines] > > -- Dave I spent untold hours over a couple of years on and off stuffing around, with this intermittancy... The mechy who did the reco changeover also put this valve back, so I felt a little better about it then. In the end I replaced it on a payer!! Jason > A $16 replacement fixed ALL this! $%@#! Thats the royal of all PITA's is the smallest thing biggest grief. :-) > Thats the royal of all PITA's is the smallest thing biggest grief. > :-) Crap! Should be been the smallest thing causing the biggest grief. > After 24 years of rattling away the PCV valve started to lose some of its > sealing when the engine (351c) was idling. [quoted text clipped - 19 lines] > > Jason They should have used OO when designing that engine... :) SignatureBen Thomas - Melbourne - Australia Current car: silver manual Holden Astra SRi Dream car: black Lamborghini Diablo Respect for the man in the ice-cream van. > > After 24 years of rattling away the PCV valve started to lose some of its > > sealing when the engine (351c) was idling. [quoted text clipped - 21 lines] > > They should have used OO when designing that engine... :) You mean 00 buckshot? Jason |
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