>The compression test is done static. The engine is rotated to top dead >center on >the compression stroke. This ensures that both valves are closed. The >propeller >is held so the incoming air pressure doesn't kick the engine over and hurts >someone. Then compressed air is pumped into the cylinder to a predetermined >pressure. As I recall, it is 100 PSI. There are two gages that are read. The >input pressure, and the pressure that is held by the cylinder. Cylinder >pressure Not to pick nits, but the standard reference pressure (aviation) is 80 PSI.
>If neither, but you can still hear air loss, it's >rings that need replacing. Piston ring leakage can be heard at the oil filler. Of course you don't need a differential compression tester to isolate a problem with rings or valves, just pump air into the suspect cylinder at TDC and see (listen) where it exits. Some automotive compression testers have a handy spark plug adapter that'll work.
================================ Angus Gordon '89 Carat Delta, Ohio '86 Syncro |
Please note - During the past 17 years of operation, several gigabytes of
Vanagon mail messages have been archived. Searching the entire collection
will take up to five minutes to complete. Please be patient!
Return to the archives @ gerry.vanagon.com
The vanagon mailing list archives are copyright (c) 1994-2011, and may not be reproduced without the express written permission of the list administrators. Posting messages to this mailing list grants a license to the mailing list administrators to reproduce the message in a compilation, either printed or electronic. All compilations will be not-for-profit, with any excess proceeds going to the Vanagon mailing list.
Any profits from list compilations go exclusively towards the management and operation of the Vanagon mailing list and vanagon mailing list web site.