MX6.com - View Single Post - How To- Modifying the stock bypass valve

**SixSick6** · 3-22-05, 12:31

Looking at this http://www.dsmtuners.com/forums/showthread.php?t=97971 gave me an idea to try it on the stock bypass.

Use a screwdriver to seperate the sealant from the two housings on the stock bypass:

Don't jab the screwdriver in there as you don't want to fux up the plastic. You need to re-seal the two halves later, and you need them in as good a condition as when they had never been opened.

Use the screwdriver to go along the seal, trying to work it's way into the seal. You might want to try an exacto knife as well. I used a surgical blade and it worked wonders. You use the screwdriver for the larger seal, and use an exacto for the inside.

Now you'll be left with 4 pieces:

The spring itself is pretty hard to compress by hand, I doubt the spring is the problem rather the flimsy rubber diaphragm causing a leak.

Either way, this mod should in theory change the springs tension and make the baffle and diaphragm harder to compress under boost, therby allowing the valve to keep a better seal.

What actually happens when the valve leaks?

Well, some of the boost pressure coming through the bypass tube makes a little detour into the valve on it's way to the intercooler.

This is what is referred to as a "leak" or that it "leaks"

BTW- I have done a ghetto test that proves that it does indeed leak.

Now keep in mind that the normal lung capacity is roughly 3.6 liters to 9.4 liters in an adult male. The amount of air that can be forced out of lungs after normal expiration is typically around 1200 ml.

Basically, your lungs are pretty powerful and can apply alot of force. I'm not sure what the normal expiration would be in terms or psi or cfm, but a good deep breath follwed by a good exhalation was enough for me to know that "this valve leaks"

Hold the vacuum nipple closed with your finger and put your mouth to the bypass valves inlet (the section that is normally attached to the bypass tube)
and blow:

You can clearly hear and feel air coming out of the bottom of the bypass valve (where it would recirculate into the turbo's inlet)

I took another breath and tried it again:

Same results.

So I tried it with inspiration (inhaling):

Crusty- Can you pass me that lighter again?:

So what is the point of all of this?

The bypass valve does indeed leak. Whether or not my lungs show the same pressure as what the bypass valve see's from the turbo, I have no idea? But I'm thinking, as well as YOU SHOULD BE, that the turbo flows ALOT MORE than my lungs.

So there is the proof that it leaks with pressure forced on it, and that it also leaks from a force of vacuum, as in the turbo's inlet.

So how to fix it?

Part 2:

I was goign to go to Home Depot to buy some washers. While I was counting the change I was going to spend, I got an

A nickel looks to be an almost exact same sized diameter and is roughly the same size as a washer anyways:

So you put a nickel in the back section.

Followed by the spring.

Followed by the diaphragm.

You can also add a second nickel behind the baffle and diaphragm for added tension.

So you end up having one by my thumb and one by my finger. If you want to use two?

Here is the lip that the diaphragm covers/seals.

The position of the second nickel:

Add some glue and snap back together:

Wait for glue to cure and test.

Just some sidenotes:

I wouldn't suggest doing this if this is your only bypass valve, you might want to have an extra.

Trying one sealed bypass with one nickel and one with two nickels might be a better idea than installing one nickel, gluing, then trying to open to install two.

I used ordinary gel super glue to close the valve as the sealant was onyl a mold of plastic anyways. It wasn't an RTV type sealant.

I haven't actually tested this myself yet as my car is currently in pieces, but in theory, it should work to cure some of the valve leak.

FYI- I tested via the lung method with one nickel and with two nickels, inhalling and exhaling.

All four ways resulted in some pressure being moved, so I doubt using two nickels would be detrimental to the valve operating correctly. Meaning, I could still get air in and out, so I doubt two nickels would cause it to to close completely and not be opened by the engines vacuum or pressure.

Should help somewhat for the guys running 12-16 psi though

I'm going to head to the store for a vacuum gauge for further testing stock, one nickel, and finally with two.

3-22-05, 12:31	#1 (permalink)
SixSick6 Join Date: Sep 2001 Location: San Diego, CA, USA Age: 32 iTrader: (2)	How To- Modifying the stock bypass valve Looking at this http://www.dsmtuners.com/forums/showthread.php?t=97971 gave me an idea to try it on the stock bypass. Use a screwdriver to seperate the sealant from the two housings on the stock bypass: Don't jab the screwdriver in there as you don't want to fux up the plastic. You need to re-seal the two halves later, and you need them in as good a condition as when they had never been opened. Use the screwdriver to go along the seal, trying to work it's way into the seal. You might want to try an exacto knife as well. I used a surgical blade and it worked wonders. You use the screwdriver for the larger seal, and use an exacto for the inside. Now you'll be left with 4 pieces: The spring itself is pretty hard to compress by hand, I doubt the spring is the problem rather the flimsy rubber diaphragm causing a leak. Either way, this mod should in theory change the springs tension and make the baffle and diaphragm harder to compress under boost, therby allowing the valve to keep a better seal. What actually happens when the valve leaks? Well, some of the boost pressure coming through the bypass tube makes a little detour into the valve on it's way to the intercooler. This is what is referred to as a "leak" or that it "leaks" BTW- I have done a ghetto test that proves that it does indeed leak. Now keep in mind that the normal lung capacity is roughly 3.6 liters to 9.4 liters in an adult male. The amount of air that can be forced out of lungs after normal expiration is typically around 1200 ml. Basically, your lungs are pretty powerful and can apply alot of force. I'm not sure what the normal expiration would be in terms or psi or cfm, but a good deep breath follwed by a good exhalation was enough for me to know that "this valve leaks" Hold the vacuum nipple closed with your finger and put your mouth to the bypass valves inlet (the section that is normally attached to the bypass tube) and blow: You can clearly hear and feel air coming out of the bottom of the bypass valve (where it would recirculate into the turbo's inlet) I took another breath and tried it again: Same results. So I tried it with inspiration (inhaling): Crusty- Can you pass me that lighter again?: So what is the point of all of this? The bypass valve does indeed leak. Whether or not my lungs show the same pressure as what the bypass valve see's from the turbo, I have no idea? But I'm thinking, as well as YOU SHOULD BE, that the turbo flows ALOT MORE than my lungs. So there is the proof that it leaks with pressure forced on it, and that it also leaks from a force of vacuum, as in the turbo's inlet. So how to fix it? Part 2: I was goign to go to Home Depot to buy some washers. While I was counting the change I was going to spend, I got an A nickel looks to be an almost exact same sized diameter and is roughly the same size as a washer anyways: So you put a nickel in the back section. Followed by the spring. Followed by the diaphragm. You can also add a second nickel behind the baffle and diaphragm for added tension. So you end up having one by my thumb and one by my finger. If you want to use two? Here is the lip that the diaphragm covers/seals. The position of the second nickel: Add some glue and snap back together: Wait for glue to cure and test. Just some sidenotes: I wouldn't suggest doing this if this is your only bypass valve, you might want to have an extra. Trying one sealed bypass with one nickel and one with two nickels might be a better idea than installing one nickel, gluing, then trying to open to install two. I used ordinary gel super glue to close the valve as the sealant was onyl a mold of plastic anyways. It wasn't an RTV type sealant. I haven't actually tested this myself yet as my car is currently in pieces, but in theory, it should work to cure some of the valve leak. FYI- I tested via the lung method with one nickel and with two nickels, inhalling and exhaling. All four ways resulted in some pressure being moved, so I doubt using two nickels would be detrimental to the valve operating correctly. Meaning, I could still get air in and out, so I doubt two nickels would cause it to to close completely and not be opened by the engines vacuum or pressure. Should help somewhat for the guys running 12-16 psi though I'm going to head to the store for a vacuum gauge for further testing stock, one nickel, and finally with two. Last edited by SixSick6 : 3-23-05 at 1:48.