I know of another method to test the rings. You need the ratio meter gauge for
this one. Just put 2-3 table spoons of oil into spark plug hole and crank. The
amount of oil should seal up the rings long enough to give a reading. Don't know
how it would work on a boxer though, as the oil doesn't flow over the top of the
piston.

PerL
87 Syncro 112i

KENWILFY@AOL.COM wrote:

> After getting a van here with zero compression on one cylinder I wanted to
> test whether the compression was leaking past the valves or the rings (the
> cylinder head gasket seemed fine as no abnormal pressure was being generated
> in the coolant system).  The customer had taken the van to a local dealer who
> did a leak down test and found that it was leaking past the rings.  I wanted
> to double check thier findings (they have been wrong before) but I wanted to
> do it simply/quickly.
>
> Here is what I did:
> 1.  Unhook and ground the wire coming from the coil to the distributor cap on
> the cap end.
> 2.  Unhook the rubber hose coming from the crankcase vent "tower".
> 3.  Crank the engine over using your handy remote starter (or an assitant if
> you don't have one of these).
> 4.  If lots of air pressure and maybe even a little wisp of smoke is coming
> out of the crankcase breather "tower" then you are leaking compression past
> the rings.  If not then you are leaking it past the valves (it is either one
> or the other).
>
> This simple method basically tells you if you rings are OK or not and wether
> putting on a rebuilt head will solve your low compression problem or if it is
> time for a rebuild (if you are going to re-ring why not tear the thing down
> and do it right?)
>
> Hope this helps,
> Ken Wilford
> http://www.vanagain.com
> John 3:16
> Phone: (856)-765-1583
> Shop:   (856)-327-0027
> Fax:     (856)-327-2242