Leakdown Cylinder test, whats it mean?

[Champ196guy]

Okay, What are acceptable results of this test for a 10 year old 150 Fastrike?

[F2008]

........Using a quality leakdown tester, each cylinder should not show more than 10% loss. If any do, there is certain to be an internal problem in the making. For example, a compression reading of 120 lbs would be viewed upon as a good cylinder by the average person. This may or may not be the case. If a leakdown test of the same cylinder indicates say...20% to 25% or more leakage, it would be a good bet that excessive wear, scored cylinder, the cylinder scratched, and/or the rings stuck or damaged in a way that does not show up with a simple compression check........

Taken from- http://www.tenkillermarine.com/boatparts/tips.asp

[Champ196guy]

Thanks for the reply. Is there a standard procedure for the test? does the motor need to be warm? How long do you have to wait for readings? I have read a couple conflicting ideas. Thanks,

[DoferGofer]

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Stratos268v &raquo;</TD></TR><TR><TD CLASS="quote">........Using a quality leakdown tester, each cylinder should not show more than 10% loss. If any do, there is certain to be an internal problem in the making. For example, a compression reading of 120 lbs would be viewed upon as a good cylinder by the average person. This may or may not be the case. If a leakdown test of the same cylinder indicates say...20% to 25% or more leakage, it would be a good bet that excessive wear, scored cylinder, the cylinder scratched, and/or the rings stuck or damaged in a way that does not show up with a simple compression check........

Taken from- http://www.tenkillermarine.com/boatparts/tips.asp
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Very good information on this link.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Stratos268v &raquo;</TD></TR><TR><TD CLASS="quote">........It is advised that leakdown tests should be performed at the beginning of the compression stroke (rings just above exhaust port opening, which is the critical point), and NOT at TDC. Make sure you have flywheel locked down securely when doing a leakdown test.
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Now I wondering if I have been doing the leakdown test "wrong". I have been checking through the entire stroke to look for any bad spot that may be lurking somewhere between TDC and BDC.



Regards,