The importance of the PCV valve.

[mad4jags]

Hi all,just thought I'd share my findings with you.
My 1998 Puma had been suffering from rather high oil consumption,around half a litre per 1000mls.The other 3 cars use virtually nothing between annual services,which amounts to around 2000 miles per car.
The car in question had only covered 43,500 at the time and I was convinced that she had endured a life of short,cold start journeys(having lived nearly all her life in Essex under elderly female company)so I suspected bore wear due to Nicasil failure,where condensation due to insufficent engine temperatures over time can lead to sulphuric attack of the plating.
However,the engine has always performed very well,plenty of power and NO SMOKE,and a compression test revealed all was in good order,which flies in the face of my original diagnosis. :?
So on with a routine service and a decision to remove the inlet manifold for further investigation.Lo and behold,we have a manifold that's soaked with oil,indicating that blowby from the crankcase is heading straight into the combustion chambers.
With the manifold out of the way access to the plastic oil seperator box and PCV valve located below was a doddle,so off they came.
The seperator was heavily gunked up with oily crud,however the PCV valve appeared to be fine,giving it a shake it rattled indicating that its inner parts were free and functioning.However having a new replacement to hand it was clear that the old valve was fully open,you could suck air only one way in the new valve,the old allowing air to pass in both directions,thus allowing oil to enter the inlet...although how the engine was smoke free is a mystery!!
Upon cleaning out the oil seperator and inlet manifold then reassembling with the new valve I can confirm,nearly a year and 1500 miles later,that oil consumption is drastically improved,back in line with the others :grin:
A valuable lesson learned....this small, plastic,always overlooked component is worth including in your service schedule.
I have no doubt the old valve was the original 21 year old item,and the rest of the fleet looked to be in the same boat!!
I think replacement every 2-3 years,at a cost of £20 for a genuine Ford part is a small price to pay for a healthy,clean engine. :grin:
Sorry for the long winded post..lol.

 

[steve90]

You're damn right about that PCV valve, as I have discovered recently.
I pulled it out and noticed the plunger had fell into the crank case...

I will have to remove the sump to check for any broken pats in the bottom end.

See pic...

 

[DOH]

Strange to see that's happened as I don't think they are supposed to come apart

 

[mad4jags]

Oh dear,that looks like the casing end and the plunger have came apart there. :?
I hope there hasn't been any damage to the engine with that lot rattling around inside :x One small consolation is the parts are plastic,which will probably have broken up in the crankcase,coming off worse than the harder metal engine parts...hopefully!!
Such a small,relatively cheap component has the potential to cause a lot of misery and there's not even a mention in the service schedule :roll:
I will routinely renew these every 3rd service. :thumbs:

 

[DOH]

I will have to remove the sump to check for any broken pats in the bottom end.

Its unlikely to require sump removal. I would however recommend you drain the oil into a clean container. Any broken bits of plastic will hopefully then come out via the sump plug hole.

If you had recently changed the oil before discovering this, you could then replace the sump plug and pour that oil through a funnel with an in built fine mesh strainer, back into the engine & replace the oil filter.

 

[steve90]

Ok, I completely dismantled the intake off the engine and searched out the parts.
One piece of plastic was found in the black air box behind the intake, and I also found the METAL plunger in there!
I was surprised to find the plunger was metal.

Due to the design of the PCV valve i can;t be certain the old plunger even had a metal ball.

I put the new (2nd hand) PCV valve in and changed the oil.
I never found any metal balls in the used oil, so I restarted the engine and all is well. I haven't driven the car yet. I will be going for a test run later today or tomorrow.

 

[mad4jags]

I don't think there is metal ball inside the valve,just the plunger and spring.
That's lucky you found the parts inside the oil separator box,at least it stopped them from finding their way into the crankcase.
Sounds like your engine will be fine :grin:

 

[steve90]

Just an update on this.
I changed the PCV valve for a 2nd hand one.
The car works but its still giving me other issues so this will have to do until I get a new one.
I have made a new post about it.

One thing i have learned though, is that if there are any leaks on the 3 way pipe or any defects inside the PCV valve the engine will cut out quite quickly. Should the PCV valve fail on a long run. that could be quite an expensive recovery.

As a side note. I noticed Puma PCV valves are made of plastic, but I noticed some Focus and other brands of PCV valve are metal, surely it would be more reliable to have the matel part considering the heat at the front of the engine block.

Does anyone know of a metal replacement that is compatible?

 

[mad4jags]

I've also noticed some valves are metal rather than plastic,infact I have a metal valve for a Jaguar V8 engine in my tool cabinet,which is very similar to the Puma's(hardly surprising as Ford owned Jaguar at the time).
However I didn't use it as it takes quite a bit more effort to open it,so it's obviously designed to operate at a different pressure range than the Puma's valve.
I would personally stick with a new genuine part,which you know is guaranteed to work as intended. :thumbs: