How much pumping to 20psi on boost leak test

[turbotsi92]

I did a boost leak test the other day, and I can hear a leak on the back of my throttle body, put my question is even with that leak, shouldn't I be able to pump it up past 1-2 psi. I pump and pump, and it will not go past that. It sounds like it is barely leaking off, but I guess if it is enough I can hear it, it must be bad huh.

 

[FastGS-T]

mine wont pump past 1-2 psi either, your alright man.

i epoxyd around my throttle body to get rid of that leak, give it a try its worth it!

 

[turbotsi92]

mine wont pump past 1-2 psi either, your alright man.

i epoxyd around my throttle body to get rid of that leak, give it a try its worth it! [/QUOTE

Did you epoxy around the outside of the TB, or take it apart and put some gasket sealer pm the gasket. Did that fix your problem?

 

[92GSXBaltimore]

your throttle body shaft seals are prob shot, and make sure your biss o-ring isnt leaking either.

 

[steve]

Trying to pressure test your intake with a hand pump only works if you don't really have any leaks to begin with. It doesn't take much of a leak to make it impossible to build any pressure and contrary to FastGS-T asserting that this is OK, it's not.

You need a better air source. It sounds like you don't have an air compressor since your using some type of hand pump. Go pick up one of the air tanks they sell at places like Walmart and fill it at the gas station.

You also need to make sure that when your testing your engine isn't stopped at some place where more than one set or valves in any cylinder is open. TDC is the worst place since both sets of valves in cyl 4 are open in overlap. If you look at the cam specs you'll see where the valves open and close specifically, but if you aim for 30* before or after TDC you'll be good.

Epoxying your throttle body to seal leaks isn't the smartest idea either. Someday you might need to take things apart and then you have a real mess. It's much better to just get a new gasket or seal.

Steve

 

[turbotsi92]

Thanks for the comments, Steve I put a brand new gasket on both sides of the throttle body already, so it could very well be the shaft seals. I will check them out . My BISS screw is not leaking.

 

[shadowdrag]

I've just did a leak test the other week and I found BISS screw leaking if you put in about 7psi of air into it. I used a bike pump found a couple of leaks, but when I used an airtank I found more leaks than ever: BISS,TB, BOV, FPR, screws,vacuum hose, fuel lines.

Go get yourselve a airtank at K-mart it is worth it. I got mine for only 24.99 there, I think Target carrys it too, because ACE and HOME DEPOT do.

 

[Steve Hebert]

Is it possible to lose air thru the cylinders. If intake valve is open at all?

 

[steve]

Is it possible to lose air thru the cylinders. If intake valve is open at all?

Sure, rings don't seal 100%. Cylinder leakdown testing helps you measure the losses from rings and valves.

Steve