"Bill Daniels" wrote in message news:mSJdc.103965$gA5.1394034@attbi_s03...
"nauga" wrote in message
ink.net...
Has anyone got any suggestions on how to
find an intake leak that don't involve standing close to a
turning propellor? Any other troubleshooting advice?
Timing checks good for both mags, BTW. Chrome cylinders,
bayonet CHT probes.

Dave 'testy' Hyde



I use the blow side of a VERY CLEAN shop vac to pressurize the intake. Use
cardboard and a lot of duct tape to seal off the air box and fit the vacuum
hose. You have to plug the exhaust too since a cylinder may have both intake
and exhaust valves open.

We use the shop vac thing to pressurize the exhaust system to
check for monoxide leaks in the cabin heat system, as per the Canadian
AD that applies to all Canadian aircraft, and also required by Cessna
on their airplanes in the latest maintenance schedules. The intake and
exhaust valves have so little overlap that they present no problem,
and if there is any, a slight turn of the prop stops it. And we find
leaks in those exhaust systems, too, before they get dangerous. Leaks
you'd never spot with your eyeballs alone.
Another respondent was concerned about vacuum motor life, and he's
right. Got to avoid running the vac for too long with so little
airflow through it. We use an old household canister vacuum, reserved
just for this sort of thing, thoroughly cleaned out, no bag or
anything, and labelled clearly.

Dan