Boost leak that i cant pinpoint

[DeeBo]

ok so i just got done replaceing the seals on my TB. and im doing a boost test and YES no leaks from the tb at 20psi but i hear somthing from the ether end on the intake mani... NOOOOO anther leak... anyway i just replaced the hose from the bov/wg t to the mani. boost test it agen and around 15 psi i hear it agen soo i replace the hose next to it runing into the lil fuel presser solenoid, boost test and still hear it.. its not the hose to the fuel rail so i reall have no idea where its coming from in there. i got a stethoscope and its right in that area but i dunno what els it could be

 

[kenamond]

ok so i just got done replaceing the seals on my TB. and im doing a boost test and YES no leaks from the tb at 20psi but i hear somthing from the ether end on the intake mani... NOOOOO anther leak... anyway i just replaced the hose from the bov/wg t to the mani. boost test it agen and around 15 psi i hear it agen soo i replace the hose next to it runing into the lil fuel presser solenoid, boost test and still hear it.. its not the hose to the fuel rail so i reall have no idea where its coming from in there. i got a stethoscope and its right in that area but i dunno what els it could be

Are you sure it's not leaking out of the VC breather or PCV valve?

Even if your PCV isn't leaking, ring blowby and valve stem leaks can bleed off a good bit of boost test air. Pull your VC breather hose and "tap" the end (of the nipple on the VC or end of the hose, depending on what you pull off), but don't cap it for more than a second or you'll pressurize your crankcase (bad).

If a fair amount of air is leaking out of the VC breather, and it's not your PCV valve, do the leak test on a fully warmed up motor. That makes a HUGE difference on these leaks-that-aren't-really-boost-leaks. I was leaking down 1psi/second from 20psi with a cold motor and 1psi every 5 seconds on a warm motor (good enough in my book).

 

[DeeBo]

no i dont belive so the leak is coming out on the ether side of the mani. but i replace the pcv hose and did like u said and its good to go.... hmmmm so lost ill see if i can get the motor starts ahahha thanx

 

[kenamond]

no i dont belive so the leak is coming out on the ether side of the mani. but i replace the pcv hose and did like u said and its good to go.... hmmmm so lost ill see if i can get the motor starts ahahha thanx

I'm not sure if I'm understanding what you're saying. The PCV valve is different than the hose. The valve screws into the back-passenger side of your valve cover. It's supposed to be a one-way valve (only letting air OUT of the valve cover). If it's bad, it can leak air INTO the valve cover which will then leak out the valve cover breather back into your intake pipe. You can unscrew the PCV from your valve cover and do a boost leak test. If air is leaking out through the PCV valve, you need a new one.

However, even if this valve is working perfectly, you'll still leak around the piston rings and valve stem seals. All of this has nowhere to escape except the valve cover breather.

So pull the hose off of your valve cover breather nipple (passenger end of the valve cover) and do a boost leak test. If your PCV valve is not leaking, but you're still leaking a lot of air out of the VC breather, then you should warm up the motor and repeat the test. The piston expands, and the rings elongate when hot, and this closes up the gaps that let air leak by during a boost leak test. Same with the valve stems.

You may be hearing leaks from the IM, but you might be hearing air leaking by the rings or valve stems that you can only hear from the IM.

Anyway, it's an easy thing to do, and you'll definitely leak less test pressure on a warmed-up motor and have a better idea whether or not you got all of your boost leaks.

 

[DeeBo]

the leak im hearing is coming from drivers side of the valve cover... its not IM ### i got rid of them im really thinking its the hose runing from the mani into the fuel presser solenoid but like i said i replaced it buttttttttt i just noticed that the nipple coming out from the mani for the hose can screw out sooooo thinking of taking it off and teflon taping it....... allso got the car started and its idealing high (just replaced TB seals) so needs some adjusting, but i noticed my vacum is reading like -18 is this normal? i just got the boost guage so im not sure what i should be around?

 

[kenamond]

the leak im hearing is coming from drivers side of the valve cover... its not IM ### i got rid of them im really thinking its the hose runing from the mani into the fuel presser solenoid but like i said i replaced it buttttttttt i just noticed that the nipple coming out from the mani for the hose can screw out sooooo thinking of taking it off and teflon taping it....... allso got the car started and its idealing high (just replaced TB seals) so needs some adjusting, but i noticed my vacum is reading like -18 is this normal? i just got the boost guage so im not sure what i should be around?

IM=intake manifold, and I doubt you got rid of that .

Get a spray bottle, fill it with really soapy water (use dish soap) and spray the area down really good, then do the leak test. Look for bubbles. Really bad leaks will break the bubbles (and you'll not see them), but smaller leaks will foam up. If you suspect that the leak is at the threads for that nipple, you could verify that if you see bubbles.

I'm not sure if teflon tape is the way to go or not. Maybe high-temp RTV would be better - ask around.

If you're idling high, that may be a vaccuum leak somewhere on your intake manifold (maybe the same place where you think you have a boost leak). While the car is idling, spray some starting fluid where you think the leak is. If the idle goes up, you have a vaccuum leak near that area (it is sucking in the starting fluid somewhere).

What elevation do you live at? This has a big effect on what vaccuum you should see at idle and also what you should see when decelerating. I live at 7200 feet, so my vaccuum is -14psi at idle and -19psi when decelerating. You can find sea level vaccuum values by searching - I don't remember.

 

[DeeBo]

well i live about 2 hours south of fairbanks... im pertty high up ahahahha Alaska.... i noticed on my stock boost guage that the the vaccum wasnt that low tell i had the boost leak... anyway what is starter fluid? like firestarter fluid ahahahaha but hey man thanx alot for helping me out here car has been down for 3 weeks waiting on seals so im really wanting to get back on the road

 

[kenamond]

well i live about 2 hours south of fairbanks... im pertty high up ahahahha Alaska.... i noticed on my stock boost guage that the the vaccum wasnt that low tell i had the boost leak... anyway what is starter fluid? like firestarter fluid ahahahaha but hey man thanx alot for helping me out here car has been down for 3 weeks waiting on seals so im really wanting to get back on the road

Starting fluid is just some REALLY flammable liquid in a spray can for helping to start a car. Like if your car won't start, and you want to find out if you have spark, you can spray starting fluid in the intake, and if it fires, you know you have a fuel delivery problem, but if it doesn't fire, you don't have spark. Or if you have a really old car that is hard to start after sitting for a month, you can spray that into the intake to help get it started. Any auto parts store will have it.

What elevation are you at?