Boost leak at cylinder #4

[ska]

hey guys long time...

just did a boost leak test to keep up with some maintence and i have a major leak @ 10psi at cylinder#4... is there some sort of seal i have to replace on the head or is it the valve cover o-ring?

[ch1873857]

boost leak... or compression test.... not sure how you can have a boost leak at certain cylinders? vacuum leak?

[ska]

boost leak... or compression test.... not sure how you can have a boost leak at certain cylinders? vacuum leak?

boost leak.

i held the boost test @ 10psi with a homemade boost tester and there was major air leak coming out of the cylinder. spark plug washer seemed fine...

[ska]

after a few trials i think i know the problem

i did the boost test with my PCV system still hooked up; hose coming from the block to catch can, to valve cover T, to intake. would this cause air to leakout from the cylinder if i had a bad o-ring or valve cover gasket?

[Hoffman5982]

A boost leak test is done on the charge piping, not the engine.

[ch1873857]

yes with throttle plate closed.

you probably think you have a leak but what iff....... your exhaust valves were open???