So, this is interesting.

[Jiggalude]

I made a home made boost leak tester with a gauge on the end. I had been testing all day and couldn't pin down a leak, but it sounds like it's coming from the TB area. I decide to switch to testing the IC and everything that is attached to, which includes my BOV. So I'm pressurizing the system and the BOV starts to blow off, but my gauge is reading 0 on the BLT. So, now I'm assuming I've been over pressurizing my system, because I could never get it to hold any pressure at all. What is the stock BOV rated to PSI wise?

 

[Zdrummer15]

An uncrushed 1g bov will usually handle 18-20 psi without leaking.

 

[LiquidX]

Are you using a spray bottle filled with soapy water to find all of your leaks? The stock BOV is fine being a 1g, you want to pressurise the system to MORE than what you will be running and it should hold the pressure for a little bit.

Keep searching and spray everything down. Start at the TB elbow first and when you fix all of those leaks, move to before the IC. Lastly connect it to the turbo. Common leaks are the TB shaft seals, BISS, injector seals, IM gasket, couplers not making a complete seal, old/cracked/pin holes in vacuum lines.

 

[Jiggalude]

I understand all of that, the only problem is the gauge I had on the BLT wasn't reading any PSI, but apparently it was being pressurized enough to make the BOV blow off. I do think I have a small leak near the TB, but I do spray everything there and I don't see any bubbles. I clamped all my connections for my catch can, and also the T for the BOV to wastegate. I checked the BISS screw, it's not leaking, I replaced old worn out injector O rings, so they aren't leaking. The TB gasket is new and the elbow gasket is not leaking. I don't know what else is leaking that area, unless the source for the BOV on the intake manifold is leaking. Also, my J pipe is as tight as I can get with the metal gasket in between and that is still leaking. Are the metal gaskets reusable? Is there any PSI that is too much for the system? Like is 30 psi too much?

 

[LiquidX]

Try to hook up your gauge to the pressure source to make sure it's busted or not.

Keep spraying, you'll eventually find the bubbles.

DO NOT tee off of the BOV for the wastegate.

For the j-pipe, if you are using allen head bolts you'll need to chop a allen key to make it fit so you can tighten it all the way down. A thin layer of RTV will help seal it too and yes, metal gaskets are reuseable for a while.

 

[Jiggalude]

I did connect it to my pressure source it is working, but I don't understand why if there was enough pressure in the system for the BOV to "blow off" didn't it show up on my gauge. I'm going to make another blt tomorrow. Also, my J pipe doesn't have a nipple on it to use for a boost source for the wga, which is why it was tapped into the bov. Where else do you suggest I hook it up to? And I did cut an allen key to put the j pipe on, but I'm going to have to put some RTV on it cause it's just not sealing.

 

[LiquidX]

Have you checked to make sure your BOV isn't actually leaking itself which might be the "sound" you are hearing?

Consider putting a nipple on the j-pipe if your turbo doesn't have one. Teeing off of the BOV is "acceptable" for a temoprary solution but should not be used long term. Shorter the line between the boost source and wastegate the better.

 

[T Money]

Is the BOV actually holding pressure then randomly blowin off or is it just leaking air as soon as you pressurize the system?

 

[Jiggalude]

The BOV held fine when I ran it at 11 psi. What is the best way to test to make sure it is holding.

 

[LiquidX]

Pressurize the system before the BOV and look for bubbles forming on it and feel for air coming out of the valve relief.

 

[Jiggalude]

Pressurize the system before the BOV and look for bubbles forming on it and feel for air coming out of the valve relief.

I'm going to take the BOV off itself and test it today, and see how much pressure it will hold. It didn't seem to leak when I had first gotten the car, but then again I was only running 11 psi.

 

[pj91gsx]

Ive done a lot of boost leak tests on a lot of different cars. In conclustion, I have never had a car come in without a leaking throttlebody. My recent car 97 2g awd, all stock, 109k miles, slightly leaking throttle body. Ive seen TB that leak worse but i went ahead and threw orings in it with grease just like the other 8 or so dsms that had leaking TBs. When the TBs leak its hard to detect them with soapy water, you just have to listen to it. Chances are its leaking, our cars are running on 15 to 20 years old, seals that arent luberated, dry rot. Also the stock 2g bov blows off at 14psi, and the stock 1g blows off at 17 psi exactly according to my boost gauge. If you need info on TB seal replacement, go to VFAQ.com. The only TB that ive seen that hasnt leaked was from my jdm swap. Good luck!!

 

[jrohner]

You're testing the BOV with the boost line hooked up right? If not it will leak because boost isn't pushing down on it, only up on it to open it.

 

[Jiggalude]

Ive done a lot of boost leak tests on a lot of different cars. In conclustion, I have never had a car come in without a leaking throttlebody. My recent car 97 2g awd, all stock, 109k miles, slightly leaking throttle body. Ive seen TB that leak worse but i went ahead and threw orings in it with grease just like the other 8 or so dsms that had leaking TBs. When the TBs leak its hard to detect them with soapy water, you just have to listen to it. Chances are its leaking, our cars are running on 15 to 20 years old, seals that arent luberated, dry rot. Also the stock 2g bov blows off at 14psi, and the stock 1g blows off at 17 psi exactly according to my boost gauge. If you need info on TB seal replacement, go to VFAQ.com. The only TB that ive seen that hasnt leaked was from my jdm swap. Good luck!!

it does sound like it's coming from the TB, but I just replaced the TB gasket. However I did not replace the gasket that is on the intake elbow, but it is a new gasket.

 

[LiquidX]

Not talking about the gaskets, we are talking about the throttle body shaft seals. There are 2 total, the first one is behind the TPS and the other is on the throttle cable side. They are really #7 o rings but there are actual seals to buy for the replacement.

Soapy water WILL detect a leaking shaft seal as the air is being forced past the seal.

 

[Jiggalude]

Alright, well I just removed and then remounted my TB and intake elbow, because it was definitely leaking from the TB. If it still leaks tomorrow then I will have to replace the seals.

 

[LiquidX]

Here is a link to some seals. I'm sure ExtremePSI would get it to you faster but $7 handling fee and then PA sales tax will be more than the cost of the seals.

Throttle Body Seals

 

[Jiggalude]

I'm guessing that this is pretty much a sure leak with these seals?

 

[pj91gsx]

I'm guessing that this is pretty much a sure leak with these seals?

I havent seen a dsm that hasnt had leaky seals. Though i never bought new seals, i bought orings. Theres an article on vfaq.com To get the orings its less than a dollar, and napa ordered them for me. So I got them faster than i could order seals, Id rather have the orings and grease anyway, because the seals dont seem to be very strong. But some people like the oem stuff, its a preference.