allenhah

iTrader: (4)

Hey guys...just got through with installing a single turbo with a Greddy Type R BOV, and I did research on what the nipples are for, but I'm wondering if there's something wrong with the BOV.

On the diagram from 93motorsports.com, they show the lower nipple separated from the upper nipple with the light blue-colored rubber diaphragm:



But when the car is idling, and the upper nipple is hooked up to a vacuum source, I can feel air being sucked in through the lower nipple, which seems in my mind that this is causing an air leak, which I think is causing problems since the BOV hose is tee'd with the Profec B controller motor.

For those of you with Greddy BOVs, does the lower nipple suck air at idle? I would think that the rubber membrane should separate the lower nipple from vaccum and therefore not vent or suck any air. Does this indicate that the membrane might be ripped?

Thanks in advance for any help in understanding this thing!
Allen

allenhah

iTrader: (4)

The more I think about it, the more I think something is wrong with the BOV. I tried creating vacuum from the top nipple with my mity-vac, but to no avail, so I tried plugging the bottom nipple and doing the same thing, and I still can't hold any vacuum...it holds a little bit more (i.e. the needle jumps up a little bit more than with the lower hole unplugged), but it still won't hold a vacuum (or pressure for that matter)

If this is the case, can anybody tell me if the footprint of the Type R is the same as for a Type S? I'm not planning on running more than 15psi of boost anyway, so I'm thinking of getting the cheaper Type S.

iluvmy3rdgen

It won't hold vaccumn because as you pull air out of the nipple it doesn't create vaccumn but it pulls that membrane up to open the valve. The lower nipple is there as a vent for the chamber. The stock BOV's don't have this vent because of a different design. Everything will be kosher if you put a mighty vac on the upper nipple and you see the valve in the body move. Adding pressure to the vent nipple will also move the valve slightly.

allenhah

iTrader: (4)

That's what I was thinking from the picture, but when I added vacuum, I couldn't see the piston move at all. Should the piston move enough for me to actually see when vacuum is applied?

If the two nipples actually are not supposed to be isolated, then doesn't that create a fairly large vacuum/pressure leak? This makes things especially bad on my car because the profec controller is tee'd into the same line and probably can't get any pressure to control the wastegate since the pressure is bleeding out the lower nipple...

Is my reasoning off somehow?

iluvmy3rdgen

The upper and lower nipples are sepperated by a rubber membrane. The boost controller should be between the turbo and the wastegate. And yes you should be able to see the piston move, but pump it up a lot, you should see some movement.

PropDue

It really depends which spring you have in there. With the stiff spring you will really not ever see the valve move, unless there is also pressure in the charge pipe that assists in unseating the valve. Even with the standard spring, you need a strong vacuum, which should also hold steady and not deplete quickly (which indicates a leak).

Try this, apply vacuum and press on the valve a bit. It should at the very least become vastly easier to unseat.

If you do need another diaphram, they are about $60-80.

DaleClark

iTrader: (55)

No matter how stiff of a spring is in the BOV, if you apply vacuum to the top nipple, the valve should open and STAY open. If not, there's a tear in the diaphragm or some other leak that's keeping it from holding a vacuum.

I'm wracking my brain right now trying to remember about the bottom nipple. I think you can actually plumb it in to a vacuum line that connects between the turbo outlet and the throttle body for some reason - be it holding more boost, faster response, something. I've seen SOMEWHERE where that was documented, and I can't remember the details for the life of me. Greddy says you can use the lower nipple to use the BOV as a pop-off valve, BTW.

The BOV is totally rebuildable, and you can tear it down pretty easily. I'd go into it and look for tears in the diaphragm, and if so, see if you can get a new one. Or, it might be cheaper to just buy a new BOV .

Dale

DaleClark

iTrader: (55)

Just Googled it -

http://herpetology.com/dsm/bov.html

According to that site, hooking the lower manifold up to the turbo's outlet (like what goes to the boost controller) will make the BOV respond quicker. That's a Good Thing .

Dale

allenhah

iTrader: (4)

Okay so I think I've understood everything fully now. The lower nipple is almost a "seconday" nipple in that it aids in responsiveness, but it should still be isolated from the upper nipple.

And no, when I put vacuum, the piston does not move up at all...it just sucks the air through the secondary nipple. Therefore, I'm concluding that the BOV is definitely shot (probably torn membrane). I'll try taking it apart and taking a look. Anybody interested in buying a used, broken Type R BOV? I'm letting it go real cheap.

Unless...Any ideas on where I can buy the diaphragms and such?

I should've figured something was wrong from the get-go since I never heard any blow-off sounds, but this was all after a single turbo conversion, so I had no idea what to expect in terms of noises and stuff.

Thanks again for all the input guys!

DaleClark

iTrader: (55)

Any parts for the BOV would have to come from Greddy. But, the price of the parts might be worth looking into getting a new BOV entirely - hard to say.

Dale

allenhah

iTrader: (4)

I've sent an e-mail to Greddy, so hopefully I'll hear something back soon.

Has anybody else experienced failed BOVs? I didn't realize these things had limited lives...

DaleClark

iTrader: (55)

I've heard of BOV's failing, but not experienced it firsthand. Some BOV's can get dirt/oil in the path of the piston, making them move slower and jam up. Oil might degrade the diaphragm over time, if it was used on a car with a turbo that was blowing oil or something.

Unfortunately, not much with cars lasts forever. Shiny new aftermarket parts do degrade and fail over time - I've been through my share.

Dale

Alpine

I wondered what the bottom nipple was for on mine Allen, what kind of symptom are you experiencing on the bov with the engine running?

allenhah

iTrader: (4)

The bottom nipple apparently can be tee'd in with the other nipple for faster boost response, but for the most part is left vented.

For me, the symptoms were:

No blow off sound after boost
No boost control (specific to my case bc the profec controller motor is tee'd with the BOV line)
The BOV will not hold any vacuum and applying vacuum does not lift the piston
A strong air flow is felt being sucked in from the bottom nipple/hole on idle.

I have a Type S on the way, but for now, I think I'm going to just take off the line going to the BOV and essentially leave the turbo system sans BOV...the original kit didn't come with one anyway, so I'm sure it'll be fine until the replacement arrives.