A “poof bottle” helps pinpoint tiny leaks in hydraulic systems. Rinse out with parts cleaning fluid a
Fill your “poof bottle” with talc or flour
plastic one-quart/liter oil bottle. “Dry” its inside with contact cleaner and a blast of compressed air. Fill it nearly full with talcum powder or fine-ground cooking flour.
To locate a leak with a poof bottle, use compressed air to blow glop and debris from a leaky fitting, valve block or hydraulic component. Flush the area with contact cleaner to remove oily residue and leave the area “dry.”
Use the poof bottle to “poof” a film of talc or flour under, behind and all around the suspected leak. Then start the machine and activate/pressurize all hydraulic circuits and systems associated with the leaky area.
Shut off the machine and eyeball the talc/flour-coated area. Even the tiniest, slowest hydraulic leak will show up as a darker discoloration of the dry, white coating.
— Dan Anderson