Boost leak at cylinder #4 - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

ska · 07-22-2012, 08:14 PM

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 · 07-22-2012, 08:20 PM

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

ska · 07-22-2012, 08:25 PM

Quote:

Originally Posted by ch1873857

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 · 07-22-2012, 08:56 PM

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 · 07-23-2012, 11:34 PM

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

ch1873857 · 07-25-2012, 12:41 PM

yes with throttle plate closed.

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

07-22-2012, 08:14 PM	#1
ska Leaky Injector Join Date: Oct 2010 Location: Sacramento, CA Posts: 146 Trader Rating: (1) Feedback Score: 1 reviews	Boost leak at cylinder #4 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?

07-23-2012, 11:34 PM	#5
Hoffman5982 Post Whore! Join Date: Jan 2009 Location: Definitely NOT FL.... Age: 33 Posts: 2,504 Trader Rating: (25) Feedback Score: 25 reviews	A boost leak test is done on the charge piping, not the engine. __________________

07-22-2012, 08:20 PM	#2
ch1873857 Nissanaholic! Join Date: Sep 2003 Location: Andrews Air Force Base Posts: 1,906 Trader Rating: (1) Feedback Score: 1 reviews	boost leak... or compression test.... not sure how you can have a boost leak at certain cylinders? vacuum leak?

07-22-2012, 08:56 PM	#4
ska Leaky Injector Join Date: Oct 2010 Location: Sacramento, CA Posts: 146 Trader Rating: (1) Feedback Score: 1 reviews	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?

07-25-2012, 12:41 PM	#6
ch1873857 Nissanaholic! Join Date: Sep 2003 Location: Andrews Air Force Base Posts: 1,906 Trader Rating: (1) Feedback Score: 1 reviews	yes with throttle plate closed. you probably think you have a leak but what iff....... your exhaust valves were open???