On the way home from dinner tonight, I noticed my BOV wasn't making any noise and no pressure was heard being released at any given speed/rpm. Boost, EGT and fuel pressure gauges read normal still. Under the hood everything is fine - the BOV is tight, all bolts are tight, all hoses are connected, everything is completely normal. However, at idle I felt no air coming out of the BOV. I had someone revv the car and it didn't open inside to release the pressure. Could something have broken internally? Everything is hooked up and functioning like it should be, yet the BOV just stopped functioning out of nowhere. Any idea's? It's the old Blitz with the Horn, dual drive I think?

Am I safe driving the car? I have been taking it easy, shifting out of boost so pressure doesn't build up...thank you for the help and pointers as always..

 

well the fact that you're not venting any air isn't good, you're probably heating up the blower more than you should be. Check you're vacuum lines, make sure no kinks etc...

It's possible that the bov's diaphragm failed.. but unlikely.. good luck.

 

Even though I understand the concept/function of a BOV I don't know how the internals of the valve is designed. It seems like you're taking proper precaution by shifting before boost builds to prevent any unforseen problem/damage from occuring. This just makes we think back in the early 80's when Mitsu and Chrysler had all those turbos running around without any sort of BOV mechanism. I guess over the years we have created devises (elec boost controller, turbo timers, BOV, etc) to help the performance and longevity of force induction vehicles.

 

There are no kinks anywhere, that's the thing. I am shifting out of boost to avoid problems temporarily. Why is it unlikely that the diaphragm failed? The BOV doesn't open up so doesn't that suggest a failure internally?

 

well if there's no kinks, then yeah.

 

I guess there is no other logical explanation? I guess I'll switch to the HKS...although this BOV has been great and is the best looking IMHO.

 

well, just remember to get the flange

 

The plunger doodad that goes up and down (the diaphragm?) fits inside the housing with a very tight tolerance. Maybe some crud got in it and seized it up?

Try taking the BOV off and disassembling it. You've got nothing to lose, and you might find out what the problem is and fix it. I've been able to repair all kinds of stuff by doing this kind of exploratory surgery, so to speak.

 

I have had the very same issue...took it off, swapped fo rhte bypass and then right back..and it worked fine after that...

so who knows...I just wish I could get tuned so I can produce more than 4 lbs pressure...

 

Well I took StephenMax's advice. I took off the BOV and removed the horn. I pushed in on the "doodad" that lets air out and barely got it halfway up. I got some WD-40 Lubricant and squirted it all inside the "doodad". Things started loosening up and before I knew it the doodad was moving up and down 100%. So I put everything back together and started the car and voila, it works again! I tried it with and without the horn and it makes a HUGE difference in sound. Without the horn its almost dead quiet with a high pitched whistle. With the horn it's 10 times louder with that PSHHHH sound.

Anyways, at idle when I start the car the diaphram (doodad) is about 40% open. Is that normal? It closes up while revving though, so that's all that's really important I guess.

No HKS for me...for now.

 

Yeah back when I had the Blitz it was like that. The shutter would like partially be open at idle. Then if I revved it closed up. So I guess it's normal. But I switched over to the HKS.. Definitely recommend that one

 

Did you're blitz have a horn like mine? Why the HKS over the Blitz? If you didnt have the horn you can't really judge the two.

Besides, the HKS is oOglier and gayer yO.

 

mine has the large opening all metal and the mini filter for some other reason...I have never switched to the little filter for comparison at all

 

Good work!

The diaphragm is assisted by engine manifold vacuum. So at idle or anytime vacuum is high (such as when you let off throttle after revving the engine), the vacuum lifts the diaphragm open to release unneeded air from the blower. When you're boosting, the vacuum line provides positive boost pressure instead, which helps the preload spring keep the diaphragm shut against boost pressure in the charge pipe

 

I'd agree with the person who wrote that should take it apart and check the release spring/valve. You should probably try the WD-40 1st cause that shouldn't hurt. 2nd, you should take it apart and see if the assembly is rusted or corroded in some way.
I don't know how BOV's affect a SC but even newer TC cars DON'T have BOV's, they have recirculation valves which to my knowledge, don't work as well. (they work fine for stock or slightly modified appications).
I would say that you're fine even if you do decide to boost as you would only get minimal compressor surge my not having a functional BOV.
I don't know how a blitz BOV works but w/ apexi and HKS, the valve should always be closed until you're close to or in positive manifold pressure.
Good luck getting your issue resolved..
(and BTW, HKS ROCK!!!!)

 

BOV is a recirculate valve that does not recircualte...intead of bring air back to intake, BOV just blow it to the engine bay. Recirculate valves are better IMO because you will never have to wast the air that you just compressed. Without BOV or recirculate valve, compressed air will shoot back to the TC/SC and might damage them.

 

Even w/ stock recirc valves, you still get "compressor surge" but probably not as much as not being able to vent the air one way or the other. Personally for any application under 15 psi, I recommend getting whatever BOV suits you best. Anything over that, go w/ a pull type like HKS or apexi twin chamber.