Check Valves!

[Kittrell]

What do yours look like?







Ordered all(?) 5 from Audi with clamps. Just waiting for my Oetiker tool to get here and I'll change them all out.

[johnouellette]

mine look like the replacement ones you have in the bag. I have a 02 1.8t

[Zoidbort]

Those things are so ridiculously over priced. I wish there were better 3rd party made ones!

[A4TL]

yah its called usp plastic kynar check valves got them on mine $1.66 or so a piece.

work great :)

[A4 TSCHUSS]

mine look like yours and www.ecstuning.com sells them

[Dolphin18T]

I just replaced one of mine that was cracked the other day. Way over priced....

[102487thedude]

you can eliminate a lot of those vacume lines. i will post up pics of mine. you will need to get rid of your secondary air. but it is not needed for anything. and you can clear the code for it with vag com i think.

[Zoidbort]

Sweet, post some pics eh!

[B6Lovin]

yeah, if anyone needs some - I'll be removing my evap, sai, and pcv tomorrow - so i'll let mine go for like 10 bucks (for the whole lot) lol

[Kittrell]

Those things are so ridiculously over priced. I wish there were better 3rd party made ones!

The four standard ones were about $6 a piece and the multifunction was $20. Doesn't seem overpriced to me.......

[A4TL]

there's a few different sizes this one is actually too small. but i did put it on the bmw to prevent the exhaust from closing below 2000 rpm so it wasn't a loss. there's a thread around here we had a while ago discussing these.

btw you best replace the one before the N80 purge valve before it lodges plastic in the N80 purge. thats exactly what happened to me and it cost me $96 for a new N80 purge valve.

So replace them with stock or otherwise, but just replace them :)

[Kittrell]

Happen to have a pic of where the N80 is? Not sure if I ordered a replacement for there.

[F16HTON]

The N80 is in the first picture you posted. look at the valve just to the left of the bad check valve.

[Kittrell]

Ha, alrighty, then I'm good to go. Thanks.

[GermanAudi]

Sorry to sound like a noob, but what is a check valve and what does it do?

[A4TL]

allows air to pass in one direction only. blow on one and and blow on the other you'll figure it out.

trust me that check valve before the n80 is going to cost you $96 if you don't take PM measures.

btw that "special check valve" that has 3 nipples, look at it; all it is a TEE before a check valve. $1.66 for check valve. $.20 cents for tee. Same goal.

if you think my ideas are crazy go the passat world or b5 forums they've been rocking the USP kynar check valves for a long time.

Zero problems. no codes. works great.

I don't dislike oem but man they are expensive for what they do. even at $6 thats still a $1 check valve :)

[GermanAudi]

The dealership told me that my one-way check valve is bad. The quote they gave me was $104 to fix!!

[Kittrell]

The dealership told me that my one-way check valve is bad. The quote they gave me was $104 to fix!!

You have to figure labor is in there. I'd just buy the part and do it myself, hell, I am doing that.

[dougyfresh]

you can eliminate a lot of those vacume lines. i will post up pics of mine. you will need to get rid of your secondary air. but it is not needed for anything. and you can clear the code for it with vag com i think.

You can only temporarily clear the SAI code for 'insufficient flow' with VAG-COM. It will, eventually, come back.

Since Mark@ASP is tuning your car, ask him to permanently remove the code. He did that on my car for me. I have no SAI system and in the past 5,000miles I've had his software I've never gotten a CEL for SAI.

[A4Avant02]

I had a vac leak and when I went to fix it the valve seemed to crumble. I ordered the lot and replaced them as well as some section of vac line. Plastic parts and heat just don't mix well.

[GermanAudi]

What are some symptoms of a worn check valve?

[jrau13]

Do yourself a favor and don't use those one-time clamps and get some screw clamps. Much easier to work with if something goes wrong.

[kepone]

What are some symptoms of a worn check valve?

I'd like to know this too!

[SlappyB6]

yah its called usp plastic kynar check valves got them on mine $1.66 or so a piece.

work great :)

Where did you get yours, and what size would I need to replace the one in the first picture of this thread?

[AudiA4Turbo22]

what tool is that to remove the clamps?? and A4TL what check valves are u using???

[Kittrell]

I like ma Oetiker clamps. I don't foresee there to be any problems. They pop off with a flat head screw driver, or cut them with some dikes. And I have the clamp tool. Really no reason to replace them with a lesser clamp.

[My OOOO My]

The N80 is in the first picture you posted. look at the valve just to the left of the bad check valve.

What is the function of the N80?

[A4TL]

usp plastic. i bought a variety. man there was a big long thread on this already. on this forum, and on the passat forum. this isn't something new. old school stuff.

There is a big ass vacuum pump near the gas tank. It sucks fumes back into the tank. The n80 opens and closes to vacuum out these gases. When it fails (open 100%) it would suck most of the engine vacuum away causing massive misfires on all cylinders and damn near stalling.

When it fails partially open it causes the leak code, mushy brakes, hard starts, especially after filling up with gas on a hot day.

Probably could find a $20 ford part that does the same thing lol. it just is a PWM air valve. The N75 roughly does the same thing :) probably why N75 is numbered close to N80 :) man i didn't realize that until right now

[Kittrell]

I know you didn't just hint at using a Ford part on an Audi................

[kepone]

Ok, so we know the symptoms of a bad N80 now, but what are the symptoms of a bad check valve?

[Kittrell]

Ok, so we know the symptoms of a bad N80 now, but what are the symptoms of a bad check valve?

You touch it and it disintegrates in your hand.................

[kepone]

lol, well i meant more like, how does the car run if one has already disintegrated in your hand

[drmarcj]

The signs of bad PCV system are not always obvious but one part of the puzzle is a blown valve cover gasket. If you can't get good ventilation off the valve cover, pressure builds up and it starts seeping oil. Also those check valves can fail internally by allowing back pressure when they shouldn't, which is something you can't see visually - requires removing thing and trying to blow through it the wrong way.

Generally a good idea to just swap them out as part of long-term maintenance. On my last car I did them at about 160,000 miles, and found that some of them needed it and others were still fine.

[GermanAudi]

so you cannot feel the car run differently (i.e. hesitating, sputtering, rough idle) if you have a worn check valve?
How many check valves would you have to replace if you were to do routine maintenance?

[Jibberific]

Ok, so we know the symptoms of a bad N80 now, but what are the symptoms of a bad check valve?

they are bad when they look like the pictures at the beginning of this thread. if you try to blow through the black end of a good one, no air will flow through.

[A4TL]

dude if the thermoset plastic looks in any way compromised or you can't blow in the obvious direction, bad.

i'd say mine were hosed at 74K miles. turbo heat kills.

if you haven't done them, guess what. you better. time+heat=kills.

I will assume you've done the braided vac lines too.

[Kittrell]

How many check valves would you have to replace if you were to do routine maintenance?

Five

[Mikef5000]

Maybe I'm the odd man out... but it seems like there are two types of people posting here. The ones that know how easy this is, and the one's who don't have a clue. Saddly, I'm one of the ones that doesn't have a clue. I've got 107k miles on the clock now, and have yet to replace one of these things!

Can we get an official writeup on this subject, instead of piecing parts together throughout this and the adjoining threads?

How many total? (ok, 5)
Where are they located? (pictures with arrows would be awesome!)
Are they all standard sized, so we can pick them up at a local auto parts store? They all the same size (and then the one needs a T also?!).

Anything else we need to know/buy if we want to go replace all of them this weekend?

On a related side note... I noticed the braided vacuum lines don't have hose clamps on them. Are they plumbed in a way to not see boost? What keeps them from popping off?

[Kittrell]

There are five, four are identical, one is slightly different. The different one has a small, long nipple coming off of the left side that basically turns that check valve into an offset t-shape. That one is located above the intake manifold. Of the remaining four, three are located on the right side of the intake manifold. Those are all basically in the same area. The fourth, which is next to the N80 valve, is on the left side of the engine bay, about halfway up.

You can't just pick up check valve anywhere, they are some what of a specialized part. Possibly dealer only in the automotive world. I don't know if there is a Napa type of aftermarket for that. I suppose someone could look into that. As has already been said, there is a company called USP that makes them for some other function. It is the same type of part though, so it will work. And is arguably better than OEM as it's plastic instead of hardened rubber. I won't argue that either way, choose whichever you'd like. Since they are generic though, you cannot get the T'd one from them. You either need to go to the dealer for that one (or Napa if those exist in that world), or you have to plumb a T in. Why you would want to add to the headache by plumbing in more connections is beyond me. But that is an option.

They are held on by the stock Oetiker clamps. You can use a flat blade screw driver to pry them off. Of just use a sharp pair of dikes and cut them off. I prefer this method as it's quicker. You can replace them with new Oetiker clamps which you can source at the dealer or various other places. But then you will need to also purchase the special clamping tool for them. This is what I did as I am a fan of OEM, and the Oetiker clamps work very well. Or you can replace them with standard screw/band clamps that you can find pretty much anywhere. I think they look cheap though and don't want my engine bay littered with them. That is just a preference though, and most people are not that anal. You need two clamps per valve, three clamps for the T'd valve.

Install is as easy as cutting the old clamps off. Popping the hose off either end of the valve. And then reverse process. The air flow is directional though, so make sure you install the new one the same way you took off the old one. If you can't physically tell (I think the USP ones are pretty symmetric); when you take it off, blow through one end and remember which hose that was attached too. When you put the new one on, blow the sides until you hit the side that duplicates what the old one did, and install it the same way. Just do one valve at a time to reduce the risk of putting one on backwards.

Clear as mud? Good..................

[Teratorn]

Excellent write up! I just replaced one of mine and it was the one next to the N80 valve. It looked like one of the pictures posted where it's turning white. The symptoms I had for that particular valve leaking air is rough idling and hesitation on first gear when taking off from a complete stop.

Can this be detected by a boost leak test, or would there be a drop if you had a gauge?