Has any1 recently bought new PCV valves? the reason i want to know is to find out the correct functioning of them... should the internal spring push the valve up and seal around the housing or should it just rattle around inside under normal conditions?

 

I have just bought new ones from MJP as 1 of mine was a little rattly, but the 2 new ones i have received also rattle about! :confused:

If it rattles its usually fooked Bud,ie.weak spring.But if there new then your shaking them to hard :xxx: :)

No, if it rattles it still moves, it it doesn't rattle then it's gummed up with oily goop and doesn't vent anything.

what are PCV valves

hmm, a mixture of answers. they dont need to be shaken at all, you just turn em upside down and they move and vice versa, the ones i removed needed physically pressing to move.

 

however, i was told to change these valves as it started smoking on idle after 10 or 15mins... i replaced them with the new ones this evening and it continues to smoke... alot! i have done a compression check which worked out fine and so suspect the turbos... my question is, how much oil is likely to still be in the wrong side of the system to make it continue to smoke? or am i buggered and need new tubs? :(

Give it a bit of time mate,to burn off!-then check it out. :)

a good pcv will rattle when shaked.if the pcv,s were at fault then it may take 500miles + to clear the oil out.

bugger! cars out of mot and tax... cant mot it coz it smokes like fook after idling for a while, cant tax it without mot! struggling to think how i can run it for 500miles :wack:

Remember you can drive a car to the MOT center no matter how far away it is! MOT in the highlands then!!

Remember you can drive a car to the MOT center no matter how far away it is! MOT in the highlands then!!

Choice answer that Bud LOL :bow:

The PCV is a few special hoses that vent crack case gases into the intake. Some signs that they are gummed up is the dip stick pops out and the seals around the engine are prone to leak because of the build up of pressure. The bad thing about the PCV is that people don’t clean/replace them causing them to not work right. If you clean them up they will work good as new. Oh and one other thing, if you take hard turns the oil in the pan sloshes around and gets sucked up the PCV lines causing smoke to come out the left side exhaust I believe.

a good pcv will rattle when shaked.if the pcv,s were at fault then it may take 500miles + to clear the oil out.

 

as it only smokes when on idle, if i left her idling for a few hours would the smoke eventually slow down and stop once all the excess oil has burnt away? where has the excess smoke collected from the defective pcv valves, in the cats and exhaust baffles? if this is the case, if i removed the exhaust from the downpipe and its still smoking then i know me tubs are fooked after all?

what are PCV valves

 

PCV valves are small valves in the back of inlet. They release crankcase pressure by way of a small ball bearing which is spring loaded. As has been said, due to their nature, they gum up with tar and fail to work effieciently and can cause all sorts of oil burning (smoke) related issues.

My new ones 'rattled' when i got them!

My old ones didnt realy move at all!

new ones in and i havent had to clean the tailpipe for over a week where it it used to be black as fook!

Will it fail the mot for sure for a bit of pcv type smoke on idle? YOu might find the mot will pass

Will it fail the mot for sure for a bit of pcv type smoke on idle? YOu might find the mot will pass

Depends on the tester. Explain the situation and see what he says. I passed last year despite smoking out the entire workshop :rolleyes: I explained that PCV valves needed changing and I hadn't got round to it yet.

 

Mine only smoked after idling for 4-5 minutes. However, I think that it was actually the rear tub seals :(

 

Steve :)

The oil collects in the plenum. If you pull of the balance tube there might be a bit of oil down there. When I changed them I was also doing a coolant hose bypass under the plenum along with a number of other things. I cleaned out the inside on the intake for a good hour to get all the gunk and oil built up in there. You shouldn't be smoking at idle or so I wouldn't think so unless it’s that bad. You might have a seal leaking in your turbo. Go to Twinturbo.net and search this im sure has been covered.

The oil collects in the plenum. If you pull of the balance tube there might be a bit of oil down there. When I changed them I was also doing a coolant hose bypass under the plenum along with a number of other things. I cleaned out the inside on the intake for a good hour to get all the gunk and oil built up in there. You shouldn't be smoking at idle or so I wouldn't think so unless it’s that bad. You might have a seal leaking in your turbo. Go to Twinturbo.net and search this im sure has been covered.

 

As he says there will be a build up of oil in places it shouldnt be-take a while to get it out of the system.

ok iv just taken it out for a test drive. now its smoking pretty much all the time!!! on idle, normal driving and on boost! DOH! help :bow:

change the pcv valves and run the engine till its hot.remove the oil filler cap and if its breathing ie oil vapour/mist is fuming out then i would do a compression test.try the rear pots first.is the car on its first engine?

Just got my PCV kit, had a read and look but didn’t make a start this evening as it looked a trickier job than I first though. How long does it take to change the valves? Not too worried about the two front breather hoses as they look simple enough.

change the pcv valves and run the engine till its hot.remove the oil filler cap and if its breathing ie oil vapour/mist is fuming out then i would do a compression test.try the rear pots first.is the car on its first engine?

 

i will give the compression test another go but the last one after a rocky start, went well! it is on its first engine yes and has done 120,000 miles, although it does have a full nissan service history and receipts for £1000's so im confident that it has been well looked after. i am still suspicious of the tubs but at that mileage the engine is bound to be a little tired so i think a full rebuild and new tubs is the way forward. grin and bare stylie!

 

Just got my PCV kit, had a read and look but didn’t make a start this evening as it looked a trickier job than I first though. How long does it take to change the valves? Not too worried about the two front breather hoses as they look simple enough.

 

once you have cleared access it is a simple job, if you are used to working with youre hands im sure youll be fine :)

cut a 19mm spanner in half and use that as u will get better access.

The PCV can go in 2 ways apparently, stuck shut which causes pressure build up that can pop your dipstick out , or open which can cause the idle smoke.

Quick thing to try is to get a long extension and tap the pcv valve hard to try shock it loose.Worked for mine, then i took em off and cleaned em in a bath of thinners.

I mean use a socket extension bar to tap the valves

Has anyone done a PCV Valve bypass to an oil catch tank, i am thinking of doing it and i would like to know if there any advantages/disadvantages.

^^^ what he asks ^^^

and could they be responsible for a rattle that comes out as the engine is warming up. It's not there at first for about 5 minutes then it starts to rattle untill engine is propper warm. Sounds like something knocking the underside of the plastic throttle cable cover...?