Newb Question: What Happens When PCV Valve doesn't work?

[xRichieRich07x]

Just out of curiosity, what would my car show symptoms of if the pcv valve was broken or clogged? (On a n/t)

 

[antlip]

Im not positive but I think it effects gas mileage. Im not sure what else it will effect, but if your worried about the condition of yours then replace it. They cost like 6 or 7 bucks and they take a wrench and 5 mins to install. I was told to do it about every 2 or 3 oil changes for a time reference.

 

[xRichieRich07x]

hmm okay thanks I was just curious as I was reading through my handy chilton manual trying to learn haha...I was just curious that's all. Anyone else have a comment?

 

[rst95eclipse]

It's for emissions. Your crankcase has vapors that need to get bled off. The PCV releases these gases that build up. If you have a catch can and a breather, then you can vent these to the atmosphere. The PCV is a one way only valve that allows these built up gasses to escape the crankcase when the system is in vaccuum. When you build boost, it does not bled off the vapors, and the valve closes so that your compressed air does not enter the crankcase. It's worth the $6.

Edit: Opps. You have a N/T. Didn't see that. It's still worth the small amount of money. The vapors are burned in the combustion process. Keeping these gasses trapped in the crankcase is not good.

 

[xRichieRich07x]

It's for emissions. Your crankcase has vapors that need to get bled off. The PCV releases these gases that build up. If you have a catch can and a breather, then you can vent these to the atmosphere. The PCV is a one way only valve that allows these built up gasses to escape the crankcase when the system is in vaccuum. When you build boost, it does not bled off the vapors, and the valve closes so that your compressed air does not enter the crankcase. It's worth the $6.

Edit: Opps. You have a N/T. Didn't see that. It's still worth the small amount of money. The vapors are burned in the combustion process. Keeping these gasses trapped in the crankcase is not good.

I knew what it does, although i appreciate the explanation, however I just wanted to know exactly would happen if the pcv valve were to clog or break.

 

[Quasimondo]

The PCV is in essence a calibrated air leak designed to evacuate crankcase gases. The more vacuum there is in the intake manifold, the more the valve will open. A pcv that is stuck open will act like an intake leak, the most noticeable symptom being an erratic idle. If it doesn't open, then the crankcase gases cannot be properly evacuated, which increases your chances of oil sludging up and leading to total engine failure.

More info here:

http://en.wikipedia.org/wiki/PCV_valve

 

[talonTSIDriver]

the PCV valve is for more than just emmisions. Its acctually very important for a turbo car. It will reduce the amount of crankcase pressure throughout the engine. I had a bad PCV once and it made the car blow blue smoke.

 

[Ginglingston11]

hey RichieRich, talontsidriver is right your car will blow blue smoke and also your car will feel like it has lost power if the pcv valve is cloged. and also its recomended to change it every 20k miles not 2 or 3 oil changes

 

[xRichieRich07x]

alright thanks a lot for all the help guys. I was actually more wondering because of my eratic idle that I have sometimes. I'll change it and see what happens. Thanks again

 

[JayRolla]

A good thing to do is blow through the pcv valve before installing. I know its not the best test but better than nothing. I was told it should leak just from blowing through it.

Quick question when I bought my car the pcv is routed to the atmosphere. Is this ok because i cant route it to the intake mani since the original owner plugged it????

 

[xRichieRich07x]

Yeah so guess what happened!? I cracked my valve cover haha. I was checking my pcv valve when i was checking for vacuum leaks. It looked like it wasn't tightened all the way because I could see the threads on it. So I took a wrench and tightened it, barely used any force at all and it busted. (Pictures below) I was just told after that the valve covers do crack very easily. So was this my fault or just a brittle old valve cover? haha I feel like an idiot for this.

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[4wd-Eclipse]

More info
http://www.dsmtuners.com/forums/showthread.php?t=229338
http://www.dsmtalk.com/forums/showthread.php?t=158536&page=2&highlight=PVC

 

[antlip]

Ouch! A new valve cover is like 200 or 300 I forget the price. You could buy a used cover that is the same age as yours, and pray there arent hair line cracks in it from someone over tightening the bolts into it.

 

[xRichieRich07x]

yeah they sell a bunch of ebay for around 20-50 bucks used. You're right about the hairline cracks though..I'm curious to whether the reason mine cracked because it already had a small crack in it or not? Because I really did not tighten it much at all.

 

[antlip]

Couple of ideas.

The owner could have over tightened it before you and put a hairline crack in it. Then when you tightened it in by hand you could have had the threads bottomed out and you putting the wrench on it could have just snapped it off.

If im not mistaken the threads for the pcv valve are slightly angled and you could of cross threaded it in.

I personally would not buy a used valve cover off ebay. Thats just me.

 

[xRichieRich07x]

Couple of ideas.

The owner could have over tightened it before you and put a hairline crack in it. Then when you tightened it in by hand you could have had the threads bottomed out and you putting the wrench on it could have just snapped it off.

If im not mistaken the threads for the pcv valve are slightly angled and you could of cross threaded it in.

I personally would not buy a used valve cover off ebay. Thats just me.

well right now with my money limit that's all the choice I'm going to have for awhile. The other thing I'm worried about is not starting my car up for like a week before my valve cover gets here. My buddy told me it's not a good idea to start the car up with the pcv valve not in because it might shoot oil everywhere. What do you guys think about this? The car's gonna be sitting outside in 10-25 degree weather for probably at least a week.

 

[antlip]

I wouldnt worry about it sitting for a week. I dont think oil is going to come shooting out of the hole if your just at idle. I could be wrong. If u wanted to start the car super bad jb weld the piece that crack off with the pcv vale in it. The cover is trash already and pcv vavle is 7$ so welding it all together just to run your car wont hurt your pocket.

 

[xRichieRich07x]

That'd be nice if I had a welder haha but alright I just thought maybe in very cold temperatures like this it would be bad letting my car sit for a week. Especially because it takes some effort starting it just after sitting for one night

 

[antlip]

No not weld, jb weld. Read the package on what metals it can seal together. I wouldnt suggest using a welder on the vavle cover. Not unless you can tig weld. Theres alot of cleaning and so forth to do if you had a tig welder and go that route. But yea try jb weld, it can possibly make your valve cover thats cracked open any worst than it is. There are people that i know that store their car for the winter and dont start them. About 4 motnhs of down time and they start right back up. Some people have weekend cars that they dont use all the time that sit longer than 7 days. Right now my elcipse has been sitting 9 days and it will start right up.

 

[xRichieRich07x]

ooh sorry I thought you just said weld I missed the jb part plus I was wondering why you'd tell me to weld my valve cover haha. But alright thanks a lot now I'll feel okay with letting my car sit for a few days. That was the only thing that I was worried about