How do I make / buy / use / troubleshoot a boost leak tester? [merged]

[Turbo Monk3y]

All boost leak tester threads are combined here.

i read somewhere maybe the Vfaq about making or buying a boost leak tester of some sort but never found it.... the reason being my acceleration seems slower than normal and all ive done to my stock car so far is take out the air box put on a K&N filter and cut the dump tube i have my boost guage sitting in a box not hooked up yet. and since those 2 mods it when i go wot on the car i can hear the turbo spool up and it sounds nice but i can also hear a sound as my rpm increases the SHHHHHHHHHHHHHHHHHHHHHH sound does too. the sound comes from the same area as the BOV i think maybe i got a #@%#@%#@%#@% stock bov and it cant handle over 11-13 psi??? Then i shift and it makes the nice BOV sound WHOOOOSHHHH... but my car seems to be a little slower.. any ideas before i go check every tube clamp and tube????

 

[TSIMonsteR]

So what? As long as the BISS hole is plugged up, I see no reason to worry about an old o-ring (or wasting time trying to find one that fits).

The cap costs $3 from Advanced Auto Parts... cheaper then a bottle of RTV and lasts basically forever, unless lost.

 

[PieEyedPiper]

Thats a good idea too.
I'll have to try that, just be careful not to crack your VC with overtightening the PCV.

 

[deletrius]

The o.d. of the compressor inlet on all the 16G turbos is 58mm which is about 2.25". The 14b has a smaller compressor inlet. I'm not sure about the inlet of the T25 but I think it is smaller than 2.5". Better to just go ahead and measure it.

The T-25 and FPB28 inlets are 2.125" OD. A 2.5" coupler is okay for both.

There is a superior boost leak tester design out there if you're interested (more expensive, though)...but I have to go find the link.

That's what I was thinking, just couldn't say it correctly. Thanks

 

[snowborder714]

Yes, it will work, but line from the bov to the intake manifold should not be teed in to. You should be getting your boost source from the turbo, the j pipe, or the lower intercooler pipe.

 

[jw_55_55]

Well i made a boost leak tester out of a 2.5"-3" coupler so it would fit on my turbo. Now the problem that i am having is im not seeing any boost on my boost gauge when im trying to pressurize the system. i have no boost controller just running of my ext. gate.
things i have tried-

-bump the starter to move the valves

-spray soapy water on all couplers to see if i can see anything leaking out

-also checked to see if my bike pump was pushing air through the coupler which it is

so what do i do next to trouble shoot??

 

[oldman]

Bike pump = too slow, you need an air compressor.

 

[jw_55_55]

But i heard of many people just using a bike pump and not having a problem. so why would it be any different for me???

 

[snowborder714]

How long does it take you to pressurize your system with 25 psi or so?

The bike pump is just not a good idea when doing a test. If you don't have a compressor, go and buy an air tank and fill it up at your local gas station. It will save your arms a bunch as well as make the testing go faster.

 

[steve]

But i heard of many people just using a bike pump and not having a problem. so why would it be any different for me???

Because you are leaking too much air for the bike pump to stand a chance of building any pressure. No pressure no bubbles or sounds of escaping air.

 

[spawn87]

hey guys ive had some idle problems with my car when it gets hot, it starts to idle like 1600 rpms and seem to lower when i turn the a/c on ... im not sure whats causing this but i know the hight temperature outside has something to do with it, like a vac leak...well i tried to boost leak test the engine and everytime i started to fill it with my compresor i only got it to 5psi and the air starts leaking out alot its comming from my bov (its stock) am i doin something wrong? thanx

 

[93_tsi_fwd]

Try changing out your stock bov. Its known to not hold too much pressure. It might be weak already.

 

[motorboat]

try replacing your bov. Its normal for your car to drop a little rpms when you turn on the a/c, it makes the motor have to run harder.

 

[spawn87]

ok guys so i replaced the bov with an hqs i had (non-recirculating) and im still having the same problem...do you think its a vacuum leak?

 

[blcknspo0ln]

Go back and do another boost leak test. Turn your regular to 30 psi and pump the system and find out where the leaks are. Get an old spray bottle and fill it with some hand soap and water, use this to spray on any potential boost leak spots (all over the throttle body, fittings, seals, intercooler hose, etc.).

I suspect your FIAV in your throttle body giving you your headache, that along with a non working ISC ( one of it's jobs is to push back up the rpm when you turn your AC on). To sum it up, BLT your car and rebuild that TB if it's giving you issues.

 

[agarcia892003]

so i was doing a boost leak test yesterday and the only leak i could hear was coming from the end of the hose of this filter. The hose is not pluged to nothing at the end, since my intake does not have a nipple for it. Can i just get it plugged with a screw? or will this affect me? thanks in advanced guys..

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[96gstdsm]

Thats the crank case vent which is usually routed back to the intake. If you plug it, it will not be able to vent and will cause problems.
I have one of those as well, but I don't remember any leaking coming from there. Did you boost leak test it on the turbo inlet? Or after the turbo on the intercooler piping? I know when I first tested it on the turbo inlet, it went into the oil pan and could hear it all bubbling and all.

 

[gsxtasy]

Either your PCV valve is leaking air through, or you have blow-by. I would suggest drilling and tapping your intake pipe for a nipple if you can. It's best to have that hooked up so you have a properly working ventilation system.

 

[agarcia892003]

Thats the crank case vent which is usually routed back to the intake. If you plug it, it will not be able to vent and will cause problems.
I have one of those as well, but I don't remember any leaking coming from there. Did you boost leak test it on the turbo inlet? Or after the turbo on the intercooler piping? I know when I first tested it on the turbo inlet, it went into the oil pan and could hear it all bubbling and all.

yes i did the test through the turbo inlet. I don't remember having this leak last time i made a boost leak test. Thanks for the help guys. I guess im going to have to drill a hole on my intake pipe and weld a nipple on it.

 

[agarcia892003]

Either your PCV valve is leaking air through, or you have blow-by. I would suggest drilling and tapping your intake pipe for a nipple if you can. It's best to have that hooked up so you have a properly working ventilation system.

Is there a way to check if the PCV valve is bad?

 

[gsxtasy]

Is there a way to check if the PCV valve is bad?

Take it out and blow through it? Should let air out, but not in. They are cheap to replace, you might just wanna throw a new one on just in case. You could also put a check valve in the line from the intake manifold to the valve cover and not have to worry about it anymore.

Liquid/Gas Check Valves - US Plastic Corporation

 

[romeen]

gsxtasy gave you some great advice. But instead of testing your PCV valve by blowing through it I would unscrew it from the valve cover but leave it connected to the vacuum line that runs to the intake manifold. Then pressurize the system (boost leak test) and check for leakage past the valve. Your lungs cannot replicate the typical boost pressures that the system sees.

I've been running the plastic check valve for two years. It works perfectly.

 

[95redturboawd]

Well I did a boost leak test today, didn't hear any leaks other then by the throttle body (think that's what it's called, the thing that houses the throttle plate) which I assume is normal? But the problem is I did a couple pulls earlier today while watching my boost gauge, and it'd only get up to about 6-7psi then drop back to zero, even though I was still accelerating. I have my gauge in the hose that goes from the BOV to the intake manifold.

 

[steve]

Well I did a boost leak test today, didn't hear any leaks other then by the throttle body (think that's what it's called, the thing that houses the throttle plate) which I assume is normal? But the problem is I did a couple pulls earlier today while watching my boost gauge, and it'd only get up to about 6-7psi then drop back to zero, even though I was still accelerating. I have my gauge in the hose that goes from the BOV to the intake manifold.

While all sorts of boost leaks are normal they all have to be eliminated. You need to find and repair all until you can pressurize your intake to above your intended boost pressure and have the system hold that pressure without leaking or needed additional air for several mins.

It doesn't matter if you can't hear them. If it can't hold the pressure you just have to keep looking until you find them. We suggest soapy water because it help finding the smaller leaks because you can look for the bubbles.

 

[95redturboawd]

While all sorts of boost leaks are normal they all have to be eliminated. You need to find and repair all until you can pressurize your intake to above your intended boost pressure and have the system hold that pressure without leaking or needed additional air for several mins.

It doesn't matter if you can't hear them. If it can't hold the pressure you just have to keep looking until you find them. We suggest soapy water because it help finding the smaller leaks because you can look for the bubbles.

When I moved the spring in the back of the throttle body the hissing noise would change pitch/intensity. Is there a seal back there I can replace?

Note - it was hard to find a 2.5" hose to make the tester... I ended up using the rubber piece connecting the intake pipe to the turbo inlet and that worked too.

 

[romeen]

When I moved the spring in the back of the throttle body the hissing noise would change pitch/intensity. Is there a seal back there I can replace?QUOTE]

That is the classic sign of leaking shaft seals. I would recommend replacing them with the seals that MachV sells as opposed to regular orings.

Throttle Body O-Ring

Throttle Body Seals