Comp surge + Blow off Vent.

[oldcorollas]

what is the T'd vac line going to? you realyl realyl should check things like that out.. befor eposting

[Z2TT]

what is the T'd vac line going to? you realyl realyl should check things like that out.. befor eposting

T'd vacuum hose that splits into 2, one goes to the Power steering pump, other goes to the BOV.

[YLD-16L]

The BOV should have a dedicated vac line.

Ideally placed it would be just before the throttle body with a nice short vac line.

The BOV's with a larger surface/diaphragm area on the vac/boost side compared to the underside of the piston (the side that releases the pressure) have better response than those with the same surface area on both sides.

Your BOV is plenty big enough in terms of size.

[Z2TT]

I cleaned out the BOV and added some oil so the piston slides easier, made sure the vac line was on tight.

took it for a drive and it was venting real well, no compressor surge, then I began hearing compressor surge again before the vent, and at boost below 5 PSI it would not vent, but just surge.

Here is a picture of how long the vac line is.

http://img401.imageshack.us/img401/9880/bovhoseaw6.jpg

[oldcorollas]

take your foot off the pedal quicker and see what happens,.

if you take off the vac line, when does the BOV start leaking?

[Z2TT]

I tried taking my foot off the pedal as quick as I can, nothing but compressor surge now, checked and nothing has fallen off, everything is tight.

Probably need to tighten my spring.

Is my hose from the BOV to intake manifold too long?

[oldcorollas]

wopuldn7t you need a softer spring? since the air pressure inside the manifold can't push the piston up?

have you tried loosening it as much as possible? basically it should be as loose as possible, but not so much that it leaks under boost...

if you make spring tighter, how do you expect the BOV to open?

[Cuts]

yeah softer spring. Hose is short enough.

Is that a cheap ebay job?

sounds like its sticking, especially if it was good after it was oiled.
prehaps take it appart again and hit the walls of the piston and cylinder with some fine wet and dry, 1200 or so. there might be some burrs or something in there. Dont touch the end faces as this is the sealingf faces.

[oldcorollas]

i think in members ride he said Blitz BOV? blitz copy or real or?

[Z2TT]

Correct oldcorolla's It's a Blitz BOV.

I have tried running a hose directly from the manifold, under highest boost does not vent at all, only surges, I tried different spring pressures.

i took the BOV and its adaptor off.
I blocked off one end of the adapter and then Blew as hard as I could into the other end of the adaptor. I could feel air coming out of the outlet of the blow off valve, to the eye the piston seems closed at the outlet, but through the sides air is coming out,

When I blow as hard as I can with my mouth, the same amount of air comes out of the outlet as of I am blowing lightly, could this be the problem. Even at the tightest spring pressure air still leaks out of the outlet when I blow.

I think somehow the air is going between the cylinder wall on the valve, and coming out the other side, There is a little metal stopper at the inlet of the valve, that stops the piston flying out from spring pressure, i applied a light amount of silicon on the outside of this stopper.

Could this be the problem, or should it still be venting?

[Z2TT]

Ok today I tested the BOV and it doesn't leak when I blow into it.

I put a little bit of grease on the cylinder, and made sure there are no loose bits of sealant on the inside of the BOV.

I took it for a drive and it wasn't venting, just real loud comp surge every time i let off the gas.

I put a larger vacuum hose on, as i noticed the nipple on the manifold was real small (about 1.8mm internal diameter), so instead of running a small vac hose straight from manifold I put the large one back going to the T section. I also loosened the spring quite a lot (was about 9 turns on the bolt left before it would come off). Any tighter than this and it would not want to vent, I think the spring is real hard on the BOV.

Now it is venting. At real low boost, just as the turbo's are beggining to make a sound, I let off the gas and I hear compressor surge, no BOV. At medium boost I let off the gas and I hear compressor surge for a split second then BOV straight after. If I floor it, let it boost up and let off I hear just BOV. Is this normal if I hear compressor surge before BOV at low revs?

[JZA70R_92]

I also used to have a bov like you have BLITZ supersound and it worked fine…did you adjust the screw properly at the top? Mine did something similar to yours!! my screw was halfway and it worked fine....you could possibly cut the spring slighty to losen the tension but to much risk in stuffing it up...

personally I wouldnt bother with a BOV....steel wheeled turbos so nothing to worry about

[Z2TT]

Yeah I did try all sorts of different settings with the spring screw. The best I am able to get it at is How it is at now, surging slightly before venting.

[oldcorollas]

cutting the spring will INCREASE its tension.. but shorten the length..
you need softer spring...

[LeeRoy]

Also, you blowing into the valve is going to do absolutely nothing.

Theres not a chance in hell youll be able to create enough pressure with your lungs to overcome the spring. If you want to test it then go and get a bike pump with a pressure gauge.

Q. How did you plan on seeing what the valves doing while your blowing into it?