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View Full Version : Is the pancake valve supposed to be hollow?



Grangalan
02-11-2008, 07:37 PM
So i've pondered this for a while since ive noticed it a month ago. My Pancake valve is nothing but an air canal lol. its hollow , is that normal?

ILoveT
02-11-2008, 10:54 PM
It has a spring in it and some other stuff.

audiness
02-12-2008, 03:49 AM
does anyone know what it does? mine was broken and it didn't evne make a difference in teh way my car ran.

brlukosk
02-12-2008, 06:31 AM
Its part of the PCV system. Called the "puck" valve, or pressure relief valve.

"The PCV ventilates the crankcase vapors that would otherwise condense and foul the oil. Gas,oil and water vapors are present in the crankcase of the engine.

The pressure in the crankcase has to go somewhere. If not thru the PCV system,it will find a way out. Leaking valve cover gaskets,unseated and leaking oil dipsticks and leaking cam seals can result."

mike-2ptzero
02-12-2008, 06:39 AM
When I took mine out many years ago I broke it open to see what was in side, all I found was the small tube with a spring inside it but didn't find anything that looked like it changed the flow going thru the small tube.

The real PCV valve is under the intake manifold.

ModifiedA4
02-12-2008, 09:48 AM
here's the real explaination, from the S4 SSP, see the "pressure limiting valve" paragraph:
http://www.modifieda4.com/images/misc-tech/Crank_Case_Breather2.sized.jpg

Grangalan
02-12-2008, 10:44 AM
Well my puck valve has nothing inside, no spring and no tube. What does that mean to me? lol

ModifiedA4
02-12-2008, 11:03 AM
Well my puck valve has nothing inside, no spring and no tube. What does that mean to me? lol

get a new one. stat.

mike-2ptzero
02-12-2008, 11:33 AM
Well it just seems that every person that has taken that valve apart has found nothing but a spring inside of it. I wonder if anyone has taken a brand new one apart to see if it is any different.

ModifiedA4
02-12-2008, 11:37 AM
Well it just seems that every person that has taken that valve apart has found nothing but a spring inside of it. I wonder if anyone has taken a brand new one apart to see if it is any different.

i've tested a new one off line and it works exactly as stated above.

low flow/vac = no resistance
high flow/vac = the valve closes and only allows a little air through

mike-2ptzero
02-12-2008, 12:01 PM
Then it must only cover the top of the tube and then only allows air to be sucked thru the very small hole that is in the side of the tube. Thing is this part is pretty useless for any A4/S4 that is running to 8500 rpms since the pressure at that point is much to high for the amount of flow that part can flow even with both ends open. This was a major issue with the twin GT S4 I drove that was still running the stock PVC system and was being pushed to 8500 rpms on every gear going down the track. So just like everything else there will be a point when a part is maxed out for flow.

ModifiedA4
02-12-2008, 01:24 PM
Then it must only cover the top of the tube and then only allows air to be sucked thru the very small hole that is in the side of the tube. Thing is this part is pretty useless for any A4/S4 that is running to 8500 rpms since the pressure at that point is much to high for the amount of flow that part can flow even with both ends open. This was a major issue with the twin GT S4 I drove that was still running the stock PVC system and was being pushed to 8500 rpms on every gear going down the track. So just like everything else there will be a point when a part is maxed out for flow.

i think you're missing the point on how that part works. the limitation is not how much it can flow, but rather how much flow it can restrict.

under high manifold vac, it is open, therefore limiting the vac to crankcase. (like a choke)

under moderate preturbo vac, it is open, pulling crankcase venting through it.

under high preturbo vac, it closes with a small hole remaining, to limit the vac on the crank case.

the upper "flow" limit doesnt matter.

operation under high manifold vac is the same for modified cars as stock cars.

operation under high boost/high preturbo vac matters for modified cars only so far as it is restrictive enough not to pull too much vac on the crankcase.

mike-2ptzero
02-12-2008, 01:35 PM
i think you're missing the point on how that part works. the limitation is not how much it can flow, but rather how much flow it can restrict.

under high manifold vac, it is open, therefore limiting the vac to crankcase. (like a choke)

under moderate preturbo vac, it is open, pulling crankcase venting through it.

under high preturbo vac, it closes with a small hole remaining, to limit the vac on the crank case.

the upper "flow" limit doesnt matter.

operation under high manifold vac is the same for modified cars as stock cars.

operation under high boost/high preturbo vac matters for modified cars only so far as it is restrictive enough not to pull too much vac on the crankcase.



I guess you missed the point I was getting at. At 8500 rpms there will be so much crank case pressure that the stock PVC system will be a restriction on allowing enough of that pressure to be sucked out which is all I was saying and only said so because more and more A4 owners are getting to that level(well of course excluding yourself). Just have to understand this is a forum with people that drive modified A4's, not where the "little turbo" A4's owners hang out. If you haven't noticed the GT28rs is starting to be the norm and more people are going to built bottom ends, built heads and running GT30's or larger.

ILoveT
02-12-2008, 01:38 PM
I guess you missed the point I was getting at. At 8500 rpms there will be so much crank case pressure that the stock PVC system will be a restriction on allowing enough of that pressure to be sucked out which is all I was saying and only said so because more and more A4 owners are getting to that level(well of course excluding yourself). Just have to understand this is a forum with people that drive modified A4's, not where the "little turbo" A4's owners hang out. If you haven't noticed the GT28rs is starting to be the norm and more people are going to built bottom ends, built heads and running GT30's or larger.

Looks like I better leave then, along with a good chunk of the rest of the community. That was also a pretty immature attack Mike. Not all of us have the money to mod up our A4's.

mike-2ptzero
02-12-2008, 01:45 PM
Looks like I better leave then, along with a good chunk of the rest of the community. That was also a pretty immature attack Mike. Not all of us have the money to mod up our A4's.

I was just saying that more and more people are going big turbo, so talking like everyone is still stock is pretty pointless and that is all I was trying to point out. I wasn't trying to attack anyone, just pointing out the fact that there are plenty of A4's running a turbo larger then a K03/K04.


My post was just pointing out the fact that at some point this OEM part is going to be a issue for those that are pushing high hp and running very high rpms.

ModifiedA4
02-12-2008, 01:53 PM
I guess you missed the point I was getting at. At 8500 rpms there will be so much crank case pressure that the stock PVC system will be a restriction on allowing enough of that pressure to be sucked out which is all I was saying and only said so because more and more A4 owners are getting to that level(well of course excluding yourself). Just have to understand this is a forum with people that drive modified A4's, not where the "little turbo" A4's owners hang out. If you haven't noticed the GT28rs is starting to be the norm and more people are going to built bottom ends, built heads and running GT30's or larger.

LOL!

My posts have been nothing but factual regarding the original poster and follow up questions regarding the pancake valve. I see the OP is chipped K03. So you bring up big turbos and the rest of the PCV system, out of the blue. [headbang]

By the way, I think your opinion is total crap. You really dont know sh~t, and you've been fooling people here long enough.

Under high boost crankcase gases get fed directly to the pre turbo intake, which has NOTHING TO DO with the main PCV valve, which is closed.

If you think BAT setups @ 8500 kerjillion rpms leak more crank case gases then can be vented by a 1/2" dia pipe run directly to the preturbo vac, you've been hitting the pipe. Go ahead tell me im wrong, like i said I think your opinion is sh~t.

im not going to take your idiocy anymore.

mike-2ptzero
02-12-2008, 03:52 PM
LOL!

My posts have been nothing but factual regarding the original poster and follow up questions regarding the pancake valve. I see the OP is chipped K03. So you bring up big turbos and the rest of the PCV system, out of the blue. [headbang]

By the way, I think your opinion is total crap. You really dont know sh~t, and you've been fooling people here long enough.

Under high boost crankcase gases get fed directly to the pre turbo intake, which has NOTHING TO DO with the main PCV valve, which is closed.

If you think BAT setups @ 8500 kerjillion rpms leak more crank case gases then can be vented by a 1/2" dia pipe run directly to the preturbo vac, you've been hitting the pipe. Go ahead tell me im wrong, like i said I think your opinion is sh~t.

im not going to take your idiocy anymore.

LOL, yes because you and your 200whp opinion means so much to me.

At 8500 rpms there is going to be more crank case pressure then at 7500 plain and simple.
Exactly how often do you take your A4 to 8500?[rolleyes]

See there are people that DO and those that just talk about it.

ILoveT
02-12-2008, 04:33 PM
I'm not sure what to edit this too because... Well I.... PHUCK!

Grangalan
02-12-2008, 06:55 PM
Alright so everyone settle down and tell me what difference it makes to me if i have the properly functioning one or like mine is hollow. Does this have a direct affect on boost/performance or anything the like. If so then i will buy a new one, if its just as useless as some of the other shit on our car (secondary air pump,ahem)[:D] i wont bother with it. Thanks

317ssayzarc
02-13-2008, 05:15 AM
since im only revving to 7700, should i integrate the limiting valve within my catch can setup?

mike-2ptzero
02-13-2008, 07:06 AM
since im only revving to 7700, should i integrate the limiting valve within my catch can setup?


Yes if your just adding an inline catch can.

onemoremile
02-14-2008, 10:03 AM
LOL, yes because you and your 200whp opinion means so much to me.

At 8500 rpms there is going to be more crank case pressure then at 7500 plain and simple.
Exactly how often do you take your A4 to 8500?[rolleyes]

See there are people that DO and those that just talk about it.


This is a thread about a car that probably doesn't make 200whp. That opinion is relevant. Do you make fun of 3rd graders for their simple math? Everyone is at a different stage with different goals.

Your car and it's rev happy lifestyle have nothing to do with this thread. There are very few members of this forum running past 8000 rpm. Almost nobody has the crankcase pressure and blowby created by a 35r at high boost. While your info was accurate for 1% of the modified cars out there it had nothing to do with the original post. You rejected his reality and submitted your own. At least one of the 99% of the members of this forum that are affected by this have reported this as trolling.

Please put yourself in the shoes of the question asker. You've got a lot of great knowledge and can be a huge help to the community but please keep it respectful and on topic. All I've got is an email address so I don't know who even sent it but it is a correct statement. More infractions gets you booted so please just knock it off.

mike-2ptzero is being abusive and inflammatory with his postings, and actually going WAY off topic.

mike-2ptzero
02-14-2008, 10:10 AM
This is a thread about a car that probably doesn't make 200whp. That opinion is relevant. Do you make fun of 3rd graders for their simple math? Everyone is at a different stage with different goals.

Your car and it's rev happy lifestyle have nothing to do with this thread. There are very few members of this forum running past 8000 rpm. Almost nobody has the crankcase pressure and blowby created by a 35r at high boost. While your info was accurate for 1% of the modified cars out there it had nothing to do with the original post. You rejected his reality and submitted your own. At least one of the 99% of the members of this forum that are affected by this have reported this as trolling.

Please put yourself in the shoes of the question asker. You've got a lot of great knowledge and can be a huge help to the community but please keep it respectful and on topic. All I've got is an email address so I don't know who even sent it but it is a correct statement. More infractions gets you booted so please just knock it off.

How is this trolling? I am giving info that is related to the part and I stated that it is something that other people are going to run into.

onemoremile
02-14-2008, 10:26 AM
I didn't read this thread at all until receiving the email today. It was all good until 11 took it way off topic. By 13 you were in your own world completely ignoring the original topic to defend your point. By 14 people took notice.

mike-2ptzero
02-14-2008, 10:31 AM
I didn't read this thread at all until receiving the email today. It was all good until 11 took it way off topic. By 13 you were in your own world completely ignoring the original topic to defend your point. By 14 people took notice.

But do you see me attacking poeople and calling them names or going on other sites to link thread showing exactly what he is attempting to do? But yet I am the only one being warned[confused]

I guess the AZ rules only apply to ME.[rolleyes]


BTW the thread was not about a car that makes 200whp, it was about a OEM part and that is exactly what was being talked about.

brlukosk
02-14-2008, 12:34 PM
Hate to jack this thread, but I have a question related to the PCV system and pancake valve.

I have known that there has been a crack in my crankcase breather hose for quite a while. I just got around to replacing the hose yesterday, along with the T fitting and a new pancake valve.

My vac at idle has increased to 20+ HG, which is good. I am also now able to boost to 20 PSI for some reason. I am using the stock N75 and no MBC with GIAC chip.

Does this make any sense? I didnt think the PCV system had that much of an effect on boost?

Also, when I took off my pancake valve, a bunch of what seemed like gas, or water came pouring out...

The car drives very weird now (rough shifting / clunking under power transitions) and boosts very easily. Its starting to concern me..

ILoveT
02-14-2008, 12:35 PM
Sounds like something to do with your wastegate.

brlukosk
02-14-2008, 12:48 PM
Sounds like something to do with your wastegate.

How so? What should I check / look for ?

ILoveT
02-14-2008, 12:52 PM
Well what were you boosting at before you started boosting to 20 pounds?

ModifiedA4
02-14-2008, 12:53 PM
Hate to jack this thread, but I have a question related to the PCV system and pancake valve.

I have known that there has been a crack in my crankcase breather hose for quite a while. I just got around to replacing the hose yesterday, along with the T fitting and a new pancake valve.

My vac at idle has increased to 20+ HG, which is good. I am also now able to boost to 20 PSI for some reason. I am using the stock N75 and no MBC with GIAC chip.

Does this make any sense? I didnt think the PCV system had that much of an effect on boost?

Also, when I took off my pancake valve, a bunch of what seemed like gas, or water came pouring out...

The car drives very weird now (rough shifting / clunking under power transitions) and boosts very easily. Its starting to concern me..

give it a few days to see if it adapts, imho. if you have a vag-com...hook it up and check for codes.

the PCV system can have a huge effect on boost. under the intake manifold the T fitting has the main PCV valve in it. Under boost it is suppose to close, aka be forced shut. If that leaks, then boost get routed to the preturbo intake aka pancake valve and to the crankcase....which means less boost for the engine :)

brlukosk
02-14-2008, 12:54 PM
Around 15/16

It just seems weird because there is not that much extra power. Almost feels like the turbo is spinning at 20psi but not pushing the air.

ILoveT
02-14-2008, 12:56 PM
Maybe you just knocked a hose off your N75 when you were messing around, but that would give you almost unlimited boost. Hmmm... not sure.

audiFUEGO
02-14-2008, 03:19 PM
Around 15/16

It just seems weird because there is not that much extra power. Almost feels like the turbo is spinning at 20psi but not pushing the air.

i prob wouldn't push your car that hard for now until you get it taken care of. Almost sounds to me like your xchip is trying to meet its its proper boost levels and at the same time overworking your little turbo to inevitable DEATH!!

sorry i got carried away

ILoveT
02-14-2008, 03:40 PM
I had a scare today, I thought I heard the turbo lady.

brlukosk
02-14-2008, 06:31 PM
I had a scare today, I thought I heard the turbo lady.

I hate scares man..

You were right, turns out I had a hose disconnected from the n75.

Sucks, now I have to WOT to boost 15psi. Half throttle gets me about 5 to 7.

I think my n75 is bad...

-BL

ILoveT
02-14-2008, 06:33 PM
Yeah mine is bad also. You are suppose to be able to blow through the long end of the N75. It's the ambient air port. If you can't do that, it's bad. That's what all data says anyways.

brlukosk
02-15-2008, 08:23 AM
Yeah mine is bad also. You are suppose to be able to blow through the long end of the N75. It's the ambient air port. If you can't do that, it's bad. That's what all data says anyways.

Whats the correct operation supposed to get me?

I feel like I have to give it more throttle to boost than a year or so ago..

hmmm..

audiFUEGO
02-15-2008, 09:44 PM
alldata ftw!

biketsai
02-15-2008, 10:46 PM
jw, is this valve the one that looks like a DV kinda, its black, plastic, and connects to some hose and the TIP?
if so, I accidentally stepped on it, and I am going to seal it up with some silicone, should i be fine?

ModifiedA4
02-16-2008, 07:00 AM
jw, is this valve the one that looks like a DV kinda, its black, plastic, and connects to some hose and the TIP?


yah this is the one we're talking about. not sure about the fix you're planning. try it and see if it works. be careful because if anything falls into the tip, good bye turbo.[:(]

biketsai
02-16-2008, 09:31 AM
hmm, its funny because when I took it out, and shook it, all of this black crap came out.
But the crack is verrryy small.
I accidentally stepped on the top of it so the fitting coming out of it pushed in like a millimeter

brlukosk
02-16-2008, 09:34 AM
If you want to see if it still works, plug one end and blow through it. If you can see/feel the diaphragm moving up and down your good to go.

I just replaced mine and it was bad.

The whole PCV system has gunk in it like that. I cleaned it all out, it was amazing any air was able to get through it.

Regardless, the puck valve (034) was fairly inexpensive. So if in doubt, just order a replacement.

biketsai
02-16-2008, 09:53 AM
How do you feel the diagram move?
i blew into the part where it connects to the TIP and i could barely feel any air coming out.