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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


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