boost leak test question

[blksylv]

Long story short ive been having an intermittent ssue of the car bucking under heaving load at low rpms so i decided to get a boost leak tester and rule out that possiblity. so long story short pull off the intake to the turbo and put the tester on and pressurize the system and it has issues holding over 3 psi without all of the air rushing out of the bov. i kno this may seem like an obvious leak but i was wondering if performed the test correctly and if i was supposed to cap anything off . btw the bov is an hks ssqv and this is for a s13 sr20

[VNG704]

Another way to find leaks is spraying starter fluid or maybe carb cleaner in suspected areas, one at a time. The car's idle will change. Did you set motor at tdc to close the valves? Otherwise wouldn't the air just go out the other end? If you did and the air is rushing out the BOV, then you have your culprit.

[blksylv]

ya i tried finding leaks with soapy water and starter fluid but i couldnt find any. i didnt set it to tdc before i did the test either. i googled a couple things beforehand on how people did theirs and i found nothing about doing that. most of them just hooked up the tester and went from there as far as finding leaks. i was thinking the same thing about the bov but i also posted this question on a local forum and somebody stated something about the bov needing pressure to stay closed. i have the vac/boost source coming from the upper right nipple on the throttle body so i dont know if it was seeing pressure or not.

[brndck]

Did you set motor at tdc to close the valves? Otherwise wouldn't the air just go out the other end?

ummmmm :down:

i'll give you $100 if you can get all 4 intake valves closed at the same time.
(without removing the intake cam)

[niscur29]

Long story short ive been having an intermittent ssue of the car bucking under heaving load at low rpms so i decided to get a boost leak tester and rule out that possiblity. so long story short pull off the intake to the turbo and put the tester on and pressurize the system and it has issues holding over 3 psi without all of the air rushing out of the bov. i kno this may seem like an obvious leak but i was wondering if performed the test correctly and if i was supposed to cap anything off . btw the bov is an hks ssqv and this is for a s13 sr20

Is it a real SSQV? Reason asking is I just fixed some leaks in my setup and my SSQV (black ltd ed) was leaking because I didnt get the snap ring all the way in. So I took it off only to find out that the SSQV I had was a little too thick on the bottom flange and no matter how hard I tried to push the seal down the ring would never get in the slot. Found out to be a knock off, but it was cheap so lesson learned.

I had a 2nd older ssqv (REAL gold with adjustable nut on backside) and it fit the same flange perfect and the snap ring I used with it allowed it to fit perfectly. Naturally the real deal fits and seals perfectly.

[blksylv]

ya its a real ssqv, its an older version, the flange was a little thin so it could easily rotate. i put some rtv around the seal and sprayed it with soapy water at idle and no bubbles. all of the air was rushing out of the opening on front of the opening of the bov so my question is does it have to have pressure on the vac line to make it stay closed or is this bov fucked lol

[VNG704]

ummmmm :down:

i'll give you $100 if you can get all 4 intake valves closed at the same time.
(without removing the intake cam)i was just testing you, good eye. No, but my mistake. Read that somewhere. Never had to do a vac test myself. Thnx for solving his prob. :thumbsup:

What I'm sure about is some bovs can have their springs swapped out for stiffer/softer springs. If your bov is one of those, try a stiffer spring that will close it at idle. What does your boost gauge read at idle? It should be around 20-22 in hg

[blksylv]

it reads 19-21 in hg at idle, ssqvs dont have diff springs

[s13 drifta]

Sounds to me your bov is no good. I have a hks ssqv and when I cap off both sides of the intercooler pipes for a leak test, It will hold 20psi no problem. The bov should never leak with pressure in the pipes, it doesn't need vacuum to make it seal.

[blksylv]

sweet thanx, thats what i needed to know lol

[blksylv]

double post lol

[SilviaAura]

yeah its your bov...if it has the adjustment screw then tighten it up and see if that makes it hold the pressure...if not then you need a new one. The bov needs no vac to stay closed. It needs vac to open.

[blksylv]

quick question, to do a proper boost leak test on an sr does the throttle body have to be capped off. everytime i've been doing a boost leak test, air has been coming from the dipstick and that's without the tb capped off. i get mixed answers from what i've been reading online. don't really think it's a ring issue because it doesn't smoke and compression is 150 across the board. i may see a drop or two of oil in the catch can per year if that.

[cotbu]

quick question, to do a proper boost leak test on an sr does the throttle body have to be capped off. everytime i've been doing a boost leak test, air has been coming from the dipstick and that's without the tb capped off. i get mixed answers from what i've been reading online. don't really think it's a ring issue because it doesn't smoke and compression is 150 across the board. i may see a drop or two of oil in the catch can per year if that.

Technically you only want to check the intercooler piping.
So cap off anything that runs to the engine.
If your throttle body fully closes, you can leave it connected, you'll get a squeal as pressure sneaks through it ,then it fully seals.
You should have the IACV line capped, The T line to the catch can and or turbo intake capped.

You don't really want to pressurize the crank case or valve cover, with anything over 5psi.
If you set the engine at TDC like I used to do, You can pressurize the hole system(every line connected) with like 10psi. The drawback is it will slowly leak out, but you can find intake manifold leaks, valve cover leaks, boost gauge line leaks, brake booster etc. like that.(with soapy water)
The dip stick is designed to pop open from excessive pressure.

Also when people say they've done boost leak tests and find none, it's hard to believe. Especially when they do them right!

[blksylv]

awesome, thanks for the input, i could never really find anything solid as far as an answer lol.