How do you know when PCV valve is bad?

[GQMarinePilot]

Just looking at my maintenance schedule for my 99 Ram 1500 5.9 and wondering how do I know if the PCV valve is necessary.

The manual says check PCV valve and replace as necessary.

On a separate question can a scanner determine if my O2 sensors need replacing even before the lights come on telling me that they have totally failed.

Thanks...

[MoparMarcIdaho]

compared to the results of running a bad one,if it has more than 30 or so on then clock,just do it.As far as 02 sensors go,a scanner should give you readings from all sensors,if its losing mileage and power it could be that or something else,the scanner will tell you.

[powerwagon]

will only show have a code if the check engine light comes on. I work at AutoZone nights, PCV valves run like three bucks.

[HankL]

Most aftermarket PCV valves for the Dodge Magnum V8's will make a noisy 'buzz'

The official Dodge PCV is the only one I have tried so far that is quiet.

A PCV can go bad by either plugging up with tar-y deposits or by gradually getting more open and flowing more.

For tarring up, they are usually easily cleaned with a solvent like carb cleaner or WD-40. You need to free up a stopped up PCV so that the PCV system will continue to 'sweep' water vapor in the 'blowby gases' out of your block internal spaces and keep this water/acidic gases from contaminating the oil.

As far as the PCV wearing to get more open - that is usually ok as the engine will create more blowby gas as the piston rings wear. The Motorcraft EV-98 is a PCV valve made especially for that condition.

[GQMarinePilot]

So is the concensus that everyone changes their valves about every 30K miles?

I sitting just short of 60K and haven't changed my at all.

[moparmark]

i have found that if i get the prob of engine keeps stalling,replace pcv valve,prob sorted. 95 ram sport 318ci

[XxRAMxX]

GQ, I can beat that... I have just over 200,000 miles on mine with the original PCV. Nothing terrible has happened to my engine either. But, I've been meaning to do a general tune up soon... I might include that for good measure.

[dasgift]

shake the pcv valve with the engine off. if it rattles, its good; if it does not trattle, its bad because it is sticking.

to the second question, a scanner will tell you the voltage output of the O2 sensor. the voltage does change with engine conditions from the presence of O2. it will not tell you good or bad. when an O2 sensor fails, it will typically send the computer an extremely lean condition. in return the computer richens the air/fuel ratio drasticly. there will be a noticable difference in performance and mpg!

hope that helps!!

[hellhound]

Here they cost about 7 bucks, call me cheap but i just spray mine off with WD-40 and blow it dry. Shake it and put it back in..... been doing that for about 10 years now.

[MoparMarcIdaho]

and the owner insisted that I install a new one.Customer is always right,the one I pulled I put right back in the box for myself,there was nothing wrong with it.I think its about peace of mind,people want to know they are getting a good job,They do seem to make a bigger difference on fomoco stuff though,when I worked for them in the mid 80s the instructor at the factory seminars said always replace with tune up.

[Dick]

It comes home late smelling like oil!

(Sorry man, I just had to. It has rained here for 3 days straight and it's gettin' to me.)

[HankL]

Someone should try one of these modified PCV valves on a Ram and report whether it really works:

http://www.et-performance.com/tech_info.html

[Dick]

Originally posted by HankL
Someone should try one of these modified PCV valves on a Ram and report whether it really works:

http://www.et-performance.com/tech_info.html

Looks interesting, but developed for motorcycle engines. I wonder why the company isn't trying to enter the automotive aftermarket? Too small, maybe?

[MoparMarcIdaho]

But I didnt see a shovelhead listed.What a great idea!

[hellhound]

a novel concept ...an old shovelhead that dont leak oil...

[MoparMarcIdaho]

but I can always hope

[HankL]

Another modified PCV that claims to increase MPG by vacuum in the crankcase:

http://www.envalve.com/the_envalve.htm

[HemiRam]

Originally posted by GQMarinePilot
Just looking at my maintenance schedule for my 99 Ram 1500 5.9 and wondering how do I know if the PCV valve is necessary.

The manual says check PCV valve and replace as necessary.

On a separate question can a scanner determine if my O2 sensors need replacing even before the lights come on telling me that they have totally failed.

Thanks...

Hmm...remove the PVC valve. Clean both ends with disgreaser and wipe clean.

GROSS PART? Blow from the valve cover side and it should whistle on the opposite side.

However, just replace it. They are seriously very cheap.

[HemiRam]

Originally posted by GQMarinePilot
So is the concensus that everyone changes their valves about every 30K miles?

I sitting just short of 60K and haven't changed my at all.

Only when they go bad.

The 02 Sensor when clogged will show a code on the dash. However, hard starting, rough idling or stall, due to bad air/fuel mixture will result.

If you run any MMT or octane boosters with headers, expect the sensor to go bad over a small period of time. Been there and done that deal.