another boost leak topic

[4doorboost]

sorry but i need some help, so i bought a boost leak tester and sure enough my car cant hold even 5psi or even get above 5psi. i am doing the test at the throttle body so what could cause that big of a leak, i put new injetor o rings upper and lower, new throttle body shft seals and gaskets. mabe th intake manifold?? any help appreciated

 

[AnotherNewb]

I believe you need to position the motor 30 degrees past tdc to ensure that more than one valve isn't open in the same cylinder.

 

[The_Big_Weave]

Get soapy water and put it on every part of the intake it will bubble any where it is leaking.

 

[turbowop]

Quoting AnotherNewb:
I believe you need to position the motor 30 degrees past tdc to ensure that more than one valve isn't open in the same cylinder.



I've never done this on any of the multiple boost leak tests I've done to my cars. I have heard of it, but it doesn't seem to me there are many places the valvetrain can stop where there is overlap in the valves...maybe I'm just lucky? /ubbthreads/images/graemlins/dunno.gif

 

[4doorboost]

thanks, ill try to the 30degrees thing and see if that works but im starting to think intake manifold gasket

 

[4doorboost]

so i have a big leak geting through m exhaust and out of my oil cap i can hear it in the valve cover, i tryed turning my motor by hand about 30 degrees past tdc and still rightout of the exhaust. so does that mean my valves? i have hks 264/272 cams could that effect anythng?

 

[4doorboost]

also the cams were installed by rre about 2 years ago so i think they should be fine

 

[mikus]

Quote:
I've never done this on any of the multiple boost leak tests I've done to my cars. I have heard of it, but it doesn't seem to me there are many places the valvetrain can stop where there is overlap in the valves...maybe I'm just lucky?


same here. Plus one can ID leaks at a pretty low PSI and that's the general idea

 

[4doorboost]

so if the valves arent overlapping then whats causing the leak the valve stem seals? the bottom end was rebuilt not to long ago so i know the piston rings r good

 

[turbowop]

Do you have a burned valve? Have you done a compression test? Even with my HKS 272's, I've never had an issue with doing boost leak tests without spinning the motor's rotating assembly to a specific angle.

 

[4doorboost]

i dunnoi car runs fine, ill do a compression test and figure it out.. im also thinkin that this could be caused by egr correct. my egr is still there cause mines a cali car but the lines are blocked off so could the egr be stuck open?

 

[acidrumz]

i have the same hks cams setup, even with the engine tdc, the exhaust and intake valves will slightly open (bigger lobes) look for other leaks around that where mention in the posts here.

also you would want to do a compression test too while your doing tests.

 

[4doorboost]

yeah i am def getting air through the exhaust but i cant really check any other places cause i cant build boost when i test cause its escaping through the exhaust and out of the oil cap which i take off.

 

[4doorboost]

i dont have any smoke coming out of the exhaust at startup idle or wot so i dont think its a burnt valve or anything

 

[SouthCaliVR4]

do you have an egr valve on the car? could be stuck open.

 

[yeti]

Quoting turbowop:
Quoting AnotherNewb:
I believe you need to position the motor 30 degrees past tdc to ensure that more than one valve isn't open in the same cylinder.



I've never done this on any of the multiple boost leak tests I've done to my cars. I have heard of it, but it doesn't seem to me there are many places the valvetrain can stop where there is overlap in the valves...maybe I'm just lucky? /ubbthreads/images/graemlins/dunno.gif



NEVER DONE IT either but also don't know if it causing a problem /ubbthreads/images/graemlins/uhh.gif

 

Quoting SouthCaliVR4:
do you have an egr valve on the car? could be stuck open.



This sounds like the most accurate possiblity to me.

 

[4doorboost]

i do have an egr since its a cali car i dont want to to a black off, i just have the lines capped off coming from the egr, how could i check if its stuck open? shouldnt it stay closed when the engines running?

 

[SouthCaliVR4]

Use a vacuum pump, eng at idle. when you apply vacuum to the valve the engine should stumble hard if not outright stall. if not pull the valve & try to blow through the port on the intake side of the valve. there should be zero leakage. other option is to replace the gasket with a block off plate & put the egr over it, so long as you pas on NOX, they'll never know the plate is in there.

 

[4doorboost]

ok ill try this when i get home, if i put the egr over a block off plate will i get an engine code since its a cali car? so since i dont have the valve hooked up it should always be closed correct?