What are symptoms of PCV valve needing replacement?

[Shel_B]

I've never needed to replace a PCV valve. What symptoms or engine behavior might suggest a need for replacement or cleaning? Is it possible that the valve may be OK, but if it were cleaned or replaced it might work better? What about replacing it just as preventative maintenance?

 

[tmorris1]

Oil consumption and sludge under valve covers

 

[Shel_B]

Oil consumption and sludge under valve covers

So if there's no oil consumption, would there be a need to check under the valve cover?

 

[Imp4]

Remove PCV valve.

Was it a PITA to remove?
Yes = replace it.

No = Shake the PCV valve.
Does it rattle when you shake it?
Yes = OK to reinstall but spray with some carb cleaner to clean out any gunk first.
No = replace.

 

[ka9mnx]

Rough idle. Quick and dirty PCV check: Pull off the breather side (not the PCV side. With the engine running put your thumb over the valve cover hole or breather hose. If you get a vacuum the PCV should be good. If you get pressure the PCV is bad.

 

[Malo83]

I always pull the PCV valve out and spray carb cleaner thru it to clean it out, works great and it rattles like crazy, reinstall.

 

[zzyzzx]

I always pull the PCV valve out and spray carb cleaner thru it to clean it out, works great and it rattles like crazy, reinstall.

The only reason why I don't do this is because I'm concerned that the solvent used will melt the plastic.

 

[tmorris1]

So if there's no oil consumption, would there be a need to check under the valve cover?

I guess I would just replace the PCV for $5 and call it a day unless you suspect sludge

 

[Kira]

I'd bet the spring in many either weakens or is corroded by CEN (Common Engine Nastiness).
A guru says the PCV in the Ford 4.0l SOHC ('98-2011 Ranger/Explorer etc.) lasts 4 years in warm climates and 3 in cold.

 

[SoNic67]

Rough idle. Quick and dirty PCV check: Pull off the breather side (not the PCV side. With the engine running put your thumb over the valve cover hole or breather hose. If you get a vacuum the PCV should be good. If you get pressure the PCV is bad.

How in the world you will get vacuum on the valve cover side?
Even new cars will blow gases there (actually new ones might blow more than some older ones, but that's a different discussion). That's the whole reason we have PCV systems.

 

[Malo83]

The only reason why I don't do this is because I'm concerned that the solvent used will melt the plastic.

Not a problem.

 

[Rob_Roy]

My Expedition threw a code when the PVC valve stuck.

 

[ka9mnx]

How in the world you will get vacuum on the valve cover side?
Even new cars will blow gases there (actually new ones might blow more than some older ones, but that's a different discussion). That's the whole reason we have PCV systems.

They have to be pumping a lot of bypass gasses to not pull a vacuum.

 

[Lubener]

I've never needed to replace a PCV valve. What symptoms or engine behavior might suggest a need for replacement or cleaning? Is it possible that the valve may be OK, but if it were cleaned or replaced it might work better? What about replacing it just as preventative maintenance?

Replace it when it doesn't rattle when shaken.

 

[Number_35]

Experienced pinging under light load on our '97 Mazda van, starting in 2005.

Discovered when doing other repairs that the PCV valve was blocked. (It was buried under the intake manifold, so I hadn't thought of it before.)

Drivability improved dramatically.

 

[SoNic67]

They have to be pumping a lot of bypass gasses to not pull a vacuum.

You said in the quoted post:
"Pull off the breather side (not the PCV side. With the engine running put your thumb over the valve cover hole...."
With hose disconnected, who is pulling vacuum ?

 

[ka9mnx]

You said in the quoted post:
"Pull off the breather side (not the PCV side. With the engine running put your thumb over the valve cover hole...."
With hose disconnected, who is pulling vacuum ?

The PCV valve...

 

[nobb]

A guru says the PCV in the Ford 4.0l SOHC ('98-2011 Ranger/Explorer etc.) lasts 4 years in warm climates and 3 in cold.

I'd be curious what that's based on. Some models have a heated PCV which are a little more costly to replace.

 

[SoNic67]

The PCV valve...

You literally said "not the PCV side" after that. So you actually meant "PCV side of the PCV valve"??? It's very confusing. That's all.

 

[Kira]

Yo noob: A very helpful Ford mechanic on a Ranger board advises the maintenance schedule I mentioned in post #9.
Experience is what he has as well as knowledge of all the Ford bulletins, campaigns and recalls.

The PCV valves involved are not the heated type.
Interesting to me is the small diameter (3/16"?) aluminum pipe bent around the valve for heating. I never heard of this type.
Since my cold state (NJ) PCV was 15 years old, I decided to replace it. It still shook but sounded full of oil goo.
Just because a PCV valve shakes doesn't mean the valve action is complete

I hope the AutoZone replacement I bought is good enough.

One fellow removed the entire coolant circulation loop (PVC heater) claiming it was an ineffective system which also introduced failurepoints.
Perhaps he's onto something as Ford went to the heated PCV valves you mentioned.

To Number_35: Approximately how many miles were on your '97 Mazda's PCV?