Leak Tester Troubleshooting: Causes & Fixes

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Problems on this page:

Good parts failing the leak test Leaking parts passing the test Results drifting during the shift Cycle time too long Fixture or clamp problems Tracer gas tester problems Test data not recorded for traceability Long changeovers between part types

Good parts failing the leak test

Hits OEE: Quality

Symptoms: Parts that are known to be good fail the leak test, and scrap or retesting rises.

Test seals on the fixture worn or dirty

Inspect and replace the test seals, and clean the sealing faces.

Part temperature different from the master part

Let parts reach a stable temperature before testing, since warm parts change pressure.

Fill or stabilisation time too short

Check the test cycle times against the validated settings.

Leak tester not calibrated

Check the tester with the calibrated leak master.

Prevention: Tester checked with a known-good part and a calibrated leak at each shift start.

Leaking parts passing the test

Hits OEE: Quality

Symptoms: Parts with leaks pass and are found later by the customer or a downstream test.

Test pressure or time below the specification

Check the test parameters against the specification.

Leak master not used to prove the test

Run the leak master at the start of every shift and after changes.

Bypass leak around the fixture seals hiding the part leak

Check the fixture seals and the sealing faces.

Reject handling not separating failed parts

Check the reject chute or lock-out of failed parts.

Prevention: Leak master results recorded at every shift start.

Results drifting during the shift

Hits OEE: Quality

Symptoms: Leak readings drift as the shift goes on.

Room or part temperature changing

Check whether drift follows the temperature and stabilise the parts.

Test air supply pressure changing

Check the regulator and the air supply.

Seals wearing during the shift

Replace seals at a set number of cycles.

Moisture in the test air

Check the air dryer and filter on the tester supply.

Prevention: Drift trended from the tester results.

Cycle time too long

Hits OEE: Performance

Symptoms: The leak test holds up the line.

Fill and stabilisation times longer than needed

Optimise the times with a validation study.

Fixture clamping slow

Check the clamp cylinders and air.

Large internal volume

Use volume fillers in the fixture where allowed.

Retests used too often

Reduce the causes of false rejects.

Prevention: Cycle time recorded per part number.

Fixture or clamp problems

Hits OEE: Availability

Symptoms: Parts do not seat or clamp correctly in the test fixture.

Locating pins worn

Replace worn locating pins so parts seat the same way every time.

Clamp air pressure low

Check the air supply and regulator feeding the clamps.

Part variation from the previous step

Check the parts against the drawing at the sealing faces.

Fixture damaged

Repair or replace the fixture, then prove it with the leak master.

Prevention: Fixture inspected weekly.

Tracer gas tester problems

Hits OEE: Availability

Symptoms: Helium or hydrogen tracer gas tests give unstable results.

Background tracer gas level high in the area

Check ventilation and leaks of tracer gas around the station.

Sniffer or detector out of calibration

Calibrate the detector with the reference leak.

Tracer gas concentration wrong

Check the gas mix and fill pressure.

Vacuum chamber leaking

Check the chamber seals.

Prevention: Background level and calibration checked each shift.

Test data not recorded for traceability

Hits OEE: Quality

Symptoms: Results are missing for some parts in the records.

Network link to the data system lost

Check the connection and the local buffer of the tester.

Part serial not scanned

Check the scanner at the station and its read rate.

Manual retests not recorded

Record every retest with its result in the system.

Storage full on the tester

Check the tester memory and the transfer of old results.

Prevention: Data completeness checked per shift.

Long changeovers between part types

Hits OEE: Performance

Symptoms: Changing fixtures and programs takes long.

Fixtures not staged

Stage the next fixture before the change.

Program not selected automatically

Link the program to the part number.

Leak master for the new part not ready

Keep a leak master for each part type at the station.

No written changeover sequence

Write the sequence and train operators on it.

Prevention: Changeover time recorded.

Guidance only. Always follow lockout/tagout and your site's safe-work procedures, and verify against OEM manuals before acting.

Stop the same fault coming back

Recurring leak tester stops usually trace to a cause you cannot see by hand. The partner we recommend is Fabrico: it tracks OEE and downtime live from PLCs, IoT sensors or AI cameras; where cameras are fitted, the video of a stop sits next to its machine data so the cause can be reviewed; and a technician opens the work order from the stop in the same system. Data is hosted in the AWS EU region, and Fabrico and the company behind it hold ISO/IEC 27001, ISO/IEC 20000-1 and ISO 9001.

Book a Fabrico demo

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Methods that cut recurring stops: the six big losses · root cause analysis · preventive vs predictive maintenance · TPM · SMED & changeover