AMS Automotive Leak Detection

Automation 101: A Beginners Guide For Automotive Leak Detection

The automotive industry is a hotbed for leak testing applications, and demanding ones at that. In a manner of speaking, your vehicle is nothing more than a series of containers on wheels. The average vehicle has several dozen mechanical, fluid, thermal, electrical and hydraulic systems, all of which must be kept physically separate from each other in order to operate safely. These systems or “containers” must be designed, tested and assured to perform without leaks, even in extreme situations outside of normal use.  This makes the need for developing test sequences, and then performing such tests reliably, a major challenge specifically found in the automotive industry.  In this article, we discuss applications, test methods and automation opportunities in the realm of automotive leak detection.   

Automotive Leak Detection

In our recent Automation 101:  Automated Leak Testing article, we defined industrial leak testing as an exercise in first defining a permissible level of media leakage across a sealing device, and then testing the device against this specification. As all materials are permeable to some degree, influenced by temperature, pressure and other variables, “leak-proof” is not as definitive of an objective as it might sound. For example, a water bottle might hold liquid water without leaking just fine, but might excessively leak much smaller helium gas particles through the threads in its cap. Given this, a documented leakage specification allows us to determine if a seal or container is “leak resistant as intended” by direct test.    

Consider the following list of containers installed in your vehicle, and the importance of keeping each of these systems free of leaks:

Brake Fluid Reservoir Radiator Exhaust ManifoldsAir Conditioner 
Oil Pan Water Pump Intake ManifoldsFuel Tank
Oil FilterEngine Block Suspension ShocksFuel Lines
TiresAirbagsWindshield Wiper ReservoirVacuum Lines
Battery CasesBattery and Fluid TraysFuel Cell HousingFuel Tank Cap
Turbo Charger HousingEngine Heater Brake BoosterAir Brake Tank
Steering Fluid ReservoirFuse BoxVehicle Trunk Vehicle Cabin

Automotive applications are numerous, either requiring that a specific material be held in or that general foreign objects be held out. In so many words, you’d prefer gas to remain inside of your gas tank and fuel lines, while water remains outside of your trunk. Each and every one of these examples presents an opportunity to perform automated leak detection, and targets a range of business, customer service, safety, environmental or regulatory requirements in doing so.    

Automotive Leak Detection Methodology  

Leaking testing in the automotive industry comes with its own unique demands:

  • Any given vehicle has a huge quantity of parts that need leak testing. 
  • The spectrum of testing criteria for such parts is wide: internal volume, part material elasticity, clamp/seal techniques, internal feature considerations, temperature and material variations all tend to require different test parameters.
  • Very fast test cycles are required to efficiently process this massive quantity of parts.
  • The test battery must be customizable, in order to comply with design changes as well as evolving regulatory requirements over time.
  • Tolerance for test failures and test system downtime are marginal at best, requiring very precise, highly repeatable, extremely reliable test processes. 

With the above objectives in mind, we’ll review below the three best methods of leak detection specifically well-suited for automotive applications.  

  1. Pressure decay. This method includes charging the test part with a prescribed pressure of compressed gas, and then, over a period of time, monitoring any drop in pressure. If the pressure inside decreases during the test, a leak to the atmosphere would be noted. The  difference between initial and final pressure readings is used to determine pass/fail.  
  2. Vacuum decay. This method consists of pulling a vacuum on a test chamber, in which a sealed test part resides. The vacuum level in the chamber is monitored for any increase in pressure (or decrease of vacuum) over a fixed period of time. Like the pressure decay, if the chamber’s vacuum level decreases, a leak through the part that added air into the test chamber would be suspected. If a certain leakage rate is acceptable, the difference in initial and final vacuum readings determines pass/fail.  
  3. Mass flow. This leak detection test is used for parts that are either large or cannot structurally withstand static pressure or vacuum. This methodology consists of a flow of air or inert gas sent through the test part. The amount of gas sent to the part is precisely measured against the amount of gas that escapes the part, compared to the allowable leakage rate, and this difference is used to determine pass/fail.  

How to Automate Automotive Leak Detection    

Thanks to modern technology, automotive part manufacturers can garner the benefit of both fully hands-off testing as well as consistent, virtually error-free results simultaneously. When seeking out automated leak testing solutions for part fabrication, component assembly or quality inspection, there are a few initial considerations worth noting. Technical specifications, required test methods and media, and flexibility for customization around future product charges are the big ones.  

Once this base information is gathered, the next step is paramount: Choose the right automation partner. Arguably more valuable than modern technology alone, involving an expert resource for the selection, design and implementation of your automated system can be the difference between gaining an acceptable solution and gaining a transformative solution. Enlisting a partner, such as Automated Machines Systems, allows part manufacturers to gain not only access to modern leak testing technology, but also a wide body of application knowledge and expertise.   

AMS offers semi-automated and fully-automated leak detection systems for your automotive applications. Our flagship LT-401 Automated Leak Testing platform is a fully automated, fully customizable, self-checking, multi-parameter system that can be designed to accept practically any vehicle part or assembly. Our LT-401 system offers the following standard features and options:  

  • Pressure decay, vacuum decay and mass flow test procedures
  • PLC-controlled test process, from initial part load to final part removal 
  • Multiple personnel safety systems including light curtains, two-hand starts, easily accessible emergency stop buttons and automatic machine halts on alarm conditions 
  • Pre-test inspection sensors including position, presence, orientation, color, optical and proximity detection. The test machine will reject a part that might have been mis-assembled or is missing a component prior to starting a leak test 
  • Automated reporting of test result documentation for quality and regulatory compliance 
  • Incredibly customizable platform that can be modified for future part changes or entirely new parts   

As demand for automotive parts continues to grow, the need to produce and quality-check these parts is expanding faster than ever. Implementing an automated leak detection solution into your workflow offers a wealth of benefit in both customer confidence and internal total cost reduction (by way of needing less labor to produce higher quality products, with fewer downstream failure claims).  

If you have questions about automotive leak testing, reach out to us at (513) 771-3525, or by email at  We would be happy to discuss your leak testing needs.

AMS Machines

Automated Machine Systems, Inc. (AMS) increases the productivity of manufacturers by helping them design, build and implement their factory automation systems.