Found PCV valve needed replacing today, ???

[ltslimjim]

Okay, so after a year of driving this vehicle(1992 Civic VX), there is a revelation on another forum( here ) that the car manual didn't even point out: The 'mistaken' PCV valve location.

I pulled it out and found it looking like this(click on pictures to zoom):

http://img196.imageshack.us/f/1003455k.jpg/

http://img23.imageshack.us/i/1003458y.jpg/

Cleaned up:

http://img714.imageshack.us/i/1003459c.jpg/

So, I'm 4k miles into an extended OCI, the first of it's kind since owning the vehicle(using AMSOIL Signature Series 0w30 currently, owned since 230k) and this is after doing 'cleanup' intervals of 3k miles(all the while believing the PCV valve to have been a non-issue)...

My question is, since a used oil analysis won't generally show build up and I just got the oil consumption under control(dont want to pull the valve cover again etc), where should I cap my mileage on this oil since the PCV system wasn't functioning properly(I cleaned the valve up but it basically functioned partially, new one is being installed today).

My goal was to give it an used oil analysis at 5k to check for the typical wear concerns, silicon, TBN, flashpoint etc. and then to go further accordingly. I hope to get at least 10k+ out of extended OCIs, but just don't know what a clogged PCV system(lets say no sludge has formed aside) would cause to happen to the oil. Oxidize more?

 

[sangyup81]

are you sure it wasn't functioning? it could have just been dirty

 

[ltslimjim]

Originally Posted By: sangyup81
are you sure it wasn't functioning? it could have just been dirty


If it was functioning, just barely. It takes some violent shaking to get it to move at all(after cleaning) and the replacement moves so freely. There wouldn't be as much buildup from the side it seats into the breather chamber I'd imagine. Not 'terrible' but certainly not functioning like it should.

 

[MetalSlug]

replace it, since its cheap part anyway

 

[ltslimjim]

Originally Posted By: CamaroT56
replace it, since its cheap part anyway


Well, the dealer wanted $25, but I found a Purolator for $2.50ish. Whew!

The real concern is if the PCV system wasn't functioning properly, or efficiently at all times, how could this compromise an extended OCI, in other words what does this do to the oil.

 

[dave1251]

You have the right idea of getting a used oil analysis done at 5K drain enough oil for a sample then top off await the used oil analysis results then make your educated guess.

 

[Spazdog]

One of the older techs where I used to work had a saying: "If a PCV valve rattles, replace it. If it doesn't rattle, replace it."

I've heeded his advice since. Anytime a PCV Valve comes out, I put a new one in. Cheap insurance.

 

[rshunter]

Originally Posted By: Spazdog
One of the older techs where I used to work had a saying: "If a PCV valve rattles, replace it. If it doesn't rattle, replace it."

I've heeded his advice since. Anytime a PCV Valve comes out, I put a new one in. Cheap insurance.

Smart advice, I'd say. Particularly when you consider the number of engines that never get it replaced.

As an aside, I'd never seen one like the thing I pulled out of my 4.7L. It amounted to a simple restricted orifice, a pinhole in a big cylindrical hunk of plastic.

 

[ltslimjim]

Well, I did replace it, the questions I have may have to wait until a used oil analysis to see if it's affected the oil's condition.

 

[Steiner]

Nothing to worry about. PCV is for emissions mainly. It just lets your engine burn crankcase vapors which are mainly from blowby instead of letting them escape into the atmosphere. It also helps with ring seal and to control small leaks but since it is reliant on manifold vacuum it essentially does nothing under full throttle high load. However, remember that you have a fresh air intake for the PCV system. If the valve fails, vapors should still escape the crankcase via this path.

 

[ltslimjim]

Hmm, makes you wonder how some vehicle's come to have sludge at PCV valves, then? Poor maintenance in regards to OCIs, too long in severe service on conventional oil etc, allowing sludge to form and finding it's way to the PCV valve?

 

[Steiner]

Originally Posted By: ltslimjim
Hmm, makes you wonder how some vehicle's come to have sludge at PCV valves, then? Poor maintenance in regards to OCIs, too long in severe service on conventional oil etc, allowing sludge to form and finding it's way to the PCV valve?


The PCV valve is the pull side of the system. Fresh air comes in from the other side. Manifold vacuum pulls vapors from the crank case through it and those vapors will contain whatever is evaporating out of the oil (moisture from cool down, fuel, etc). As such, there will always be a form of "condensation" in the vapor and it just gunks up the line and valve eventually. It doesn't have much to do with the quality of the oil. This also why there is usually a dedicated line for the PCV instead of sharing it with other vacuum operated accessories as the stuff in the vapors can damage things like the brake booster over time.

 

[ltslimjim]

According to this diagram of my PCV system; the PCV valve is potentially problematic if clogged/dysfunctional, it's allowing ventilation to the bottom end of the engine. If you click on the link and then zoom in on the picture to the left, look at the diagram and note MY PCV valve is NOT located where the manual's diagram, picture to the right show. It came STOCK with an 'elbow' at the location in question, rather the PCV valve I pulled was down by the 2nd 'arrow' from the bottom end of the engine, mounted directly into the route for escaping fumes. The breather side has fresh air for the valve cover separately pre-throttle body.

http://www.redpepperracing.com/technical/d/2995-2/afj.png

ADDED: So, there obviously is a potential for the inability of enough ventilation to do 'something' to the oil.

My purpose for this thread was asking if anyone knows what a failed PCV valve could do to engine oil seeing extended service. Probably nothing noticeable in short intervals of service, though.

 

[Steiner]

Yes, in an inline engine you have to separate it like that. Reason being is that otherwise manifold vacuum just draws air straight from the fresh air feed instead of crankcase vapors. Kinda like when you hit a straw too hard to get it out of the paper and it puts a crack in the side. You try to suck your drink but wind up getting mostly air. V engines have the fresh air supply in one valve cover and PCV in the other.

Before the PCV was invented for emissions purposes, cars just vented the crankcase vapors straight to atmosphere. After that, they came up with the road draft tube which helped pull vapors out but they still went to atmosphere.

There may be a small impact from a bad PCV valve that shows up in the oil but with the fresh air supply run the way it is, there is always a path for crankcase vapors to exit the engine. Also consider that at wide open throttle when blowby gases are at their greatest level, the PCV valve does nothing because manifold vacuum is zero. Just trying to give a little background. Understanding how something like that works helps understand any impacts.

 

[ARB1977]

If your worried change it out. I change mine at 60K intervals.