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Old 06-13-2009, 04:02 AM   #1
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Default Compressor surge surprise attack!

I've been using this knockoff greddy bov (identical to the Greddy type s) for about 6 months and it has been working flawlessly.
A few days ago, during normal light accelleration I heard the fluttering compressor surge sound when I shifted. Complexed, I accellerated harder actually going into boost and let off an the bov did its thing normally. I accellerated lightly, not going into boost - maybe 80 kpa or so, let off the gas and again, compressor surge.
Basically it seems, at low pressures (very light accel) when I lift off the throttle the bov doesn't open now and so I get that fluttering surge, but with any boost, even 110 kpa, the bov vents normally...

So.. has anyone had a similar experience like this? Is the bov tightening up over time, as in its now taking more pressure to open it up? If so, should I try to take it apart and somehow adjust the sensitivity?
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Old 06-13-2009, 04:08 AM   #2
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I have the same thing happen with my Greddy BOV. I was under the impression the "turkey gobble" was normal.
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Old 06-13-2009, 05:06 AM   #3
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Don't you have to periodically lube the metal BOVs?
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Old 06-13-2009, 09:28 AM   #4
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I'm running the Greddy Type RS BOV, there's a common failure in the diaphram. Open it up and check for tears.

There's an issue w/ the knock-off Greddys, some of them wouldn't open up all the way. Check to see if you get full travel w/ the adjustment screw backed off completely, if not you'll have to do some grinding.
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Old 06-13-2009, 11:12 AM   #5
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i guess the only logical solution is to romp on it all the time....
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Old 06-13-2009, 11:25 AM   #6
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Quote:
Originally Posted by Savington View Post
Don't you have to periodically lube the metal BOVs?
+1

Its recommended to lube the piston on my Tial






Its a shame I cant type 1 helpful comment without utilizing the jerkit smiley
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Old 06-13-2009, 11:59 AM   #7
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What kind of lube? Just regular motor oil?

Its okay everyone needs to sometimes
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Old 06-13-2009, 12:15 PM   #8
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My friend has the EXACT some BOV on his e30.

The problem is that the spring inside will twist and shift. It's really a simple fix. Just open the whole thing up and clean out any grime and reset the springs in a manner so they are'nt binding at any point.

Shouldn't take any more than 10 minutes.
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Old 06-13-2009, 12:55 PM   #9
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Quote:
Originally Posted by viperormiata View Post
My friend has the EXACT some BOV on his e30.

The problem is that the spring inside will twist and shift. It's really a simple fix. Just open the whole thing up and clean out any grime and reset the springs in a manner so they are'nt binding at any point.

Shouldn't take any more than 10 minutes.
My buddy used to run one of these on a DSM, and the diaphragm would actually pull out of the retaining groove. After having to pull the valve in a parkiglot to reset the diaphragm about the 4th time he bought a real TiAl. It might be worth it to just go buy a valve that doesn't suck.

Also, the Turbo Dodge nerds generally don't run a BOV of any sort. Compressor surge sounds wicked sweet. My room mate put ~130k on a mildly modded 2.2 turbo LeBaron without a BOV with no issues. When he pulled the turbo apart after the motor finally let go, it had about 1/8" thrust clearance, but it still made good boost, lol.
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Old 06-14-2009, 03:10 AM   #10
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Thanks for suggestions guys. So far, this bov has worked great, and as a true Greddy type S is $150 used to $250 new I think I will look into what is ailing this one before ditching it and getting another..
Honestly, as this only happens at less than 0 psi (vacuum), I really doubt it is hurting the turbo in the way that compressor surge with no bov does, but I want to keep everything operating 100% properly, not let things get all janky on me, so I want to figure this out. I want to bump to 14 psi in the near future..
I'll try messing with the adjustment screw on the top.. I don't know how to check if it is opening fully or not... I mean wouldn't I have to turn the motor on and rev the **** out of it with my eye down in the bov outlet to see if the bov is opening all the way?
If adjusting the screw doesn't help I'll pull it apart and check the spring and diaphram - I searched this issue on google and found that a few guys out there using this bov have had diaphrams tear and one guy even made a replacement out of a bicycle tire tube instead of buying a greddy replacement diaphram..
-Ryan
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Old 06-14-2009, 05:11 AM   #11
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Corky said he's never seen damage to a compressor, when running NO BOV.
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Old 06-14-2009, 11:41 AM   #12
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Lube the piston shaft.
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Old 06-14-2009, 02:02 PM   #13
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Quote:
Originally Posted by ThePass View Post
take it apart and somehow adjust the sensitivity?
It's probably not necessary if the problem developed over time, and the above advice is likely sufficient, but to answer this question you can preform the one spring mod.

Inside the Greddy-S (real and knockoff) are two springs of different thicknesses/rates. You can pull out the smaller spring and reassemble. The one larger spring will hold 15psi without leaking.

EVO Motorsports - Evo VIII Performance Upgrades and Accessories - Type-S Single Spring Mod


edit: Disassembled:

Compressor surge surprise attack!-0.jpg

Last edited by UofACATS; 06-14-2009 at 02:32 PM.
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Old 06-15-2009, 01:46 PM   #14
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My BOV (not a tial knockoff, but whatever) accumulates grime where it seals closed, and will eventually begin to stick closed. It's a really simple fix that just involves cleaning the grime out, but I do have to do it every few months.
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Old 06-15-2009, 09:04 PM   #15
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So did cleaning fix it?
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Old 06-15-2009, 09:27 PM   #16
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I get a lot of compresser surge on my car when i lift from light acceleration. Im gunna try softening the bov adjustment or cleaning it.

I have a sr20 T25 and it costs all of $95 to rebuild so i dont care that much
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Old 06-15-2009, 09:28 PM   #17
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Quote:
Originally Posted by Splitime View Post
Lube the piston shaft.
You've been taking Hustler lessons.
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Old 06-16-2009, 06:00 AM   #18
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work and school have had all my spare time lately. When I get around to effing with the bov I'll post up
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Old 06-16-2009, 06:13 AM   #19
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Quote:
Originally Posted by kenzo42 View Post
Corky said he's never seen damage to a compressor, when running NO BOV.
He's also never seen hardware come apart on a fast turbo track car.
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Old 06-16-2009, 11:35 AM   #20
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Does anyone know if the HKS SSQV requires cleaning as well?
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