I pulled my PCV valve tonight since it's never been checked in 5 years and 70000 miles. Once I got the sucker out, I shook it and heard nothing. I then took a nail and pushed on the valve and it felt spring loaded. I blew thru it and it opened and closed fairly good. I sprayed some solvent on it and put it back in. This is the first PCV valve I inspected that was spring loaded. Most PCV valves you can shake and hear the valve rattle around (ie open and close). Is mine "normal"?


Dave

 

As far as I can tell our PCV is not spring loaded. A brand new PCV will rattle quite a bit if you shake it just a little. I just changed my PCV valve on my 95 max with 98K miles and it whould not rattle for the life of it. I highly recommend you replace it because you will see a much higher rate of carbon build up in your TOB & oil leaks can suddenly appear. BTW the valve is only $10 bucks at Nissan.

 

I have never cut open a Maxima Positive Crankcase Ventilation valve but I believe it is spring loaded. At http://www.misterfixit.com/pcvvalve.htm you will find a general discussion of PCV valves and it contains this ...
When the engine is at idle and vacuum is high the force of the vacuum overcomes the force of a spring inside the PCV Valve ...

 

At http://autos.yahoo.com/repair/results/ques079.html you will find this ...
The PCV valve is a spring-loaded valve with a specific orifice size designed to restrict the amount of air that's siphoned from the crankcase into the intake manifold. ...

 

I recently replaced a the PCV valve on a friend's 96 max and when I shook it violently I could barely hear the rattle. But with the new Nissan PCV valve it didn't take much shaking at all and I could hear the rattle loud and clear.

 

Alright, this is really weird. Some say yes the valve is okay (DBM) and others say replace it. My PCV valve is all plastic including the valve. The whole piece weighs next to nothing. Most PCV valves I've dealt with are made out of steel and have some weight to them. Since mine's plastic and spring loaded, I can see why the valve doesn't rattle open and closed (not enough weight to push on the spring). I looked at my Chiltons manual and it has a cross section of the PCV valve and it shows the valve having a spring. Like I said before, I blew thru the exit portion of the valve and air freely flowed thru easily and when I tried to blow thru the other side and it wouldn't release any air (ie it appears to be working right). Also, the valve wasn't gunked up, it just had a little oil around the base. I'll go to Nissan and check their replacement valve out, with my luck they probably changed the design and now it's metal.


Dave

 

The Nissan OEM PCV valve IS plastic...at least the container is plastic. The aftermarket one from AutoZone is plastic and it also rattles more readily than the factory one with 60k miles on it.

 

I generally replace it about every 15,000 miles, they're so cheap there really isn't any reason not to, I figure it's just preventative maintenance.

 

Exactly.

 

I guess I'm just a silly monkey I figure if it ain't broke, don't fix it.


Dave

 

Me too. In my experience many PCV valves last for the life of the car.

 

You replace belts before they break,so why not PCV valves? It is really a cheap enough part with a SUPEREASY install. Worth the 10 bucks and 10 minutes.

 

You raise a good question, one which is at the foundation of each owner's personal maintenance philosophy.

I draw a distinction between belts and the PCV valve. Belts are expected to wear out, and they are not repairable. PCV valves can be cleaned and made good as new. The consequences of an unexpected failure should be considered. You can drive long distances safely and comfortably with a stuck PCV valve, but not with a broken belt.

You are right that a replacement PCV valve costs only $10. However, I am careful with my money. I'm not pleading poverty, but I don't have money to waste.

To turn the same question back to you, do you replace your headlamp and taillamp bulbs before they burn out? I don't. I am reluctant to replace good parts.

 

I am in the habit of changing them, much the same way I change fuel filters. The stock fuel filter can be used for the life of the car in theory, but driving with one that has 110K miles on it is not a great idea.