my car has a blitz blowoff valve that was added prior to me getting my dirty hands on it.
the first few weeks i drove the car, it did it's normal "whoosh" sound when i let off to shift.
recently the sound is no longer that "whoosh" that you associate with a blowoff valve, and more a sputter. i'm not building as much boost(on autometer gauge, not factory) as i was prior to the sound change.
do blowoff valves go bad? leak boost?
not that i do not have enough on my plate of car repairs, but if it is bad are they rebuildable or do i have to bite the proverbial bullet and get a new one?
Have you increase boost or anything? They are adjustable. There'll be a set screw on top of the unit. The more the tighten it down the more pressure it takes to open it up under boost. Give it a try otherwise maybe you've got a boost leak someplace else and there's not enough pressure to open it up when the throttle body is closed under boost. I would do a vacuum leak test and pressurize the intake system to see if there's a leak and then you can see also if the bov is leaking or not. There's not much to a bov. There's an o-ring underneath the piston on the bottom of the bov that you remove and all the internals should come out. Maybe there's a tear in the diaphram.
-setscrew ontop
I'd pull it off and make sure it's not stuck. If the piston's stuck partway up in the bore, the resulting leak would cause you to build boost more slowly. It would also not dump air when needed, so you'd get your different sound.
On advice of the GRM community, I bought a genuine HK$ SSQBOV from NOPI.com (GRM Advertiser once), and that thing rocks. I've seen lots of other people with lesser BOV's biatch about having to free up pistons and otherwise constantly mess with them. The only problem I had was putting the circlip in backwards and losing it (destructions are in Japanese). After fixing that pilot error issue, no other problems.
I have a Blitz SS on my SR... It's pretty bulletproof. I'd look for boost leaks elsewhere, if you aren't building boost like you were. Possible in the feed line plumbing to the BOV?
I took mine apart once two years ago, just because I never had... cleaned everything, lubed lightly with brake caliper lube (the green stuff) and hasn't given me a lick of trouble.
well as of a little while ago the subject is moot. for a while anyway. started getting bearing noise in the bottom end.
