Date:         Sun, 31 Dec 2006 12:47:33 -0500
Reply-To:     Geza Polony <gezapolony@SBCGLOBAL.NET>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Geza Polony <gezapolony@SBCGLOBAL.NET>
Subject:      Leak Down Testing

I found this description of the leak down test procedure in the archives. Is
it right? Anything to add? Any inaccuracies?

QUOTE:

The air test or leak down test is used to determine any wear problems within
any given engine . I will explain the test very simpily to all . // You want
to bring your piston to top dead center of each cylinder to be tested or
actually the firing position NOT to the bottom center. // You will first
remove all 4 sparkplugs from your engine,also your oilcap, and if
watercooled your radiator fill cap // You will need a air compressor with a
adjustable air regulator plus a air test hose that may be purchased at your
local parts stores and it will have a end to thread into the sparkplug hole
and a male quick release end to connect to your air hose. To run the test
properly run and get the engine to operating temperature before removing
plugs. // Your FIRING ORDER is 1-4-3-2 ~~ You have a V notch on your crank
shaft pulley and that notch will show up on Number 1 cylinder and Number 3
cylinder. // You will need to find number 1 plug wire on your dist.cap and
that will lead to the drivers side towards the front of the van number 2 is
on the drivers towards the back of the van Number 3 is on the pass.side
towards the front of the van and Number 4 is towards the back of the van //
if you have standard shift place van in neutral and ebrake IT // Remove your
distributor cap and turn the V notch to the coresponding top dead center
marks ~~refer to your Bently manual ~~ You can usually turn the engine on
the alternator center nut ~ Turn engine Clockwise // Once you find Number 1
TDC // Insert your test hose into number 1 cylinder then connect your air
hose to the test hose with 0 air pressure at the air regulator,slowly turn
air up to 75 to 100lbs. Now if you have a problem in the test cylinder the
air will tell the tale // to go to next cylinder to be tested turn clock
wise 90 degrees and make sure your rotor points to the correct wire on your
dist cap // If a exhaust valve is leaking you will have air coming out the
end of the muffler .// I f the intake valve is bad you will have air coming
out the air intake or on carbed out the carb.// If you have piston ,ring or
cylinder wear problems the air will blow past the rings and into the oil
area and you will be able to hear it at the oil fill region // If your head
gaskets are bad you will see air bubbles or antifreeze coming out the
radiator fill cap .On horizontally opposed engines always replace the
piston,cylinder and rings as a kit never replace just rings, you will be
putting new round rings into 2 egg shaped objects = piston & cylinder NOW
??? The reason for having the piston at top dead center is to test the area
at the top of the cylinder and the rings for proper combustion which is the
area IN which your power and compression originates from == Combustion ) ALL
these tests can be done on 4 / 6 / 8 cylinder engines.// You can have
problems in all areas so listen in all area,s to be sure . You should also
run a a compression test first to decipher any pre air test problems !!!
Average good compression tis 150 to 170 lbs