PCV change interval

[dparm]

Audi specs that my PCV valve is "lifetime" though we all know that typically means "warranty + 1 day". My car is an 05 with about 61,000 miles. How do I know when it's time to change this valve? Is it just a preventative maintenance thing I should do now, or is it truly lifetime?

The part is about $60.

 

[Radman]

My cars have always called for 1 year or 12K miles. I noticed with synthetic oils they are always clean and free on removal. I change mine every other year but mine cost around 5 bucks.

 

[dparm]

Yeah I miss the days of the $3 ones on my Hondas.

 

[rslifkin]

I'd pull it and make sure it's not clogged up. If it's pretty clean, I'd give it a spray of carb cleaner, make sure it rattles when shaken, and put it back in. Or, if it's cheap, you could change it if it makes you feel better.

 

[dparm]

Well that's the thing...it's not cheap. I'll be doing some other maintenance at the time. I guess I can just buy it at the dealer and return it if things look good.

 

[dparm]

What are the symptoms of a bad PCV valve? Found this through a quick Google search:



The PCV valve is a simple ball check valve. It is oriented so that vapor flows from the cam/valve cover to the vacuum source, usually the intake manifold or tract. It has two failure modes:

Stuck open
Stuck closed

Stuck open would allow normal flow of crankcase oil vapor to the vacuum source, but would allow intake pressure pulses to flow back into the cam/valve cover. This could allow gasoline into the engine cases. Gasoline has almost no lubricating properties for high-pressure applications such as crank bearings and cam followers.

Stuck closed causes a slight power loss. The PCV valve has one major function and one minor side-benefit: it allows crankcase oil vapor to be burned instead of venting to atmosphere and the vacuum applied to the crankcase reduces crankcase pressure slightly. Pistons moving up-and-down pump crankcase air as wells as intake air, using horsepower to do so. Reducing the crankcase pressure reduces pumping losses.

 

[hounddog]

I'd be surprised if any vehicle manufacture calls for a 1 year 12,000 mile change in the last two decades.I can see a 'lifetime' PCV. Its a real simple valve.If anything service it on a 100,000 mile maintance or such.

 

[bepperb]

" I noticed with synthetic oils they are always clean and free on removal. "

I'm not sure if it's because of the oil or just a better design, but mine never have any junk in them and that certainly wasn't the case in some of my past cars. 12000 miles seems nuts, maybe an inspection but certainly not a replacement interval. I'd say once at 100,000 miles if everything always looks fine.

 

[calvin1]

After having three vehicles in a row with PCV valves that were not made to be easily replaced I've come to the conclusion that they should be changed when they go bad, not preventively. In nearly 500,000 miles I've never had one go bad even on the ones that were made to be easily changed so I'll just cross my fingers.

 

[mechtech2]

Once a year on modern car is too often.
Something is wrong if you need one that frequently.
But there is no hard and fast rule.
A visual inspection is a good idea. They may rattle and be OK, or rattle and be bad.

 

[dparm]

Some of the Audi guys claim it is a diaphragm which can tear and cause leakage. Does that sound right?

 

[dparm]

Oops, looks like it is a diaphragm:


its a diaphragm. The behavior is not like you might expect, it isn't just a one-way valve. Its designed to close if there is high pressure in the IM. To test the behavior, I wrapped the holes in paper towels and blew in the bottom of it. Its a straight pass thru, both ways, until there's an impedance on the IM side. if you block it, it will seal, and remain sealed until you unblock The IM side, and or stop blowing.

I'm sure I'm just inviting the quote edits on that one. For science!

From my understanding, the idea is to allow the release of crankcase pressure into the IM. But, for those times in the cycle that the IM is highly pressurized, it closes, preventing any added pressure.

 

[xBa380]

I did my valve at like 45,000 miles... It was a very easy DIY, and only cost $4-7 I believe from the stealership for the part.

Mine was clean and looked to operate just fine... But it's cheap, preventative maintenance!

 

[EricZoom]

I just changed mine on my 04' Mazda6 at 37k miles. I figured it was good preventive maintenance, considering it took 10 minutes, and cost about $6 at AZ.

 

[wander2039]

I changed the Escape's 95k when I did the plugs. Probably replace it again at 150k when I change them again. It's a royal PITA to change as it's under the intake manifold.

 

[4ever4d]

Every 24 months or 20-24k miles.Cheap and very easy to change.

 

[tig1]

Originally Posted By: Radman
My cars have always called for 1 year or 12K miles. I noticed with synthetic oils they are always clean and free on removal. I change mine every other year but mine cost around 5 bucks.


Noticed the same thing with synt. oil. Even with engines with 200K and up I might only replace the PVC once, and it was still clean. I have never had a dirty PVC valve.

 

[HTSS_TR]

I replaced PCV of my +250k miles LS400 first time last year when it had 240k miles, the OEM PCV was clean and could be in place for many thousands more miles, but since I bought a new Fram PCV valve the OEM was discarded.

 

[Vizzy]

Originally Posted By: dparm
Audi specs that my PCV valve is "lifetime" though we all know that typically means "warranty + 1 day". My car is an 05 with about 61,000 miles. How do I know when it's time to change this valve? Is it just a preventative maintenance thing I should do now, or is it truly lifetime?

The part is about $60.


dparm:

I have a couple of late model VWs and both the pcv valves are spring controlled diaphrams ...

Also rememeber that the pcv valve is part of the emissions system and as such is covered by the federal emissions warranty of generally 8 years or 80k miles whichever comes first , this may be more in some states

Unless your car is throwing a code for the pcv valve I wopuld not replace it yet, I would wait until around 100k miles because that is what it was designed for due to the CA emissions requirements .

That part really is designed to be a long life part due to strict emissions warranty requirements .

 

[Kestas]

I like these threads. I'm not that warm to the idea of 'cheap and easy insurance'. I prefer intelligent maintenance. There are too many things that can be classified as cheap and easy insurance. If you add them all up it's a boatload of money that is spent. If we can save from needlessly spending $5 here and there, it's good for the environment and better for the pocketbook.