Recreational Vans

Leak Test Procedure

Why leak testing matters

Leaks steal more than pressure. They waste energy, invite water intrusion, contaminate fluids, and degrade safety. A clear leak test procedure confirms that a system is sealed within defined limits before real world use. The procedure sets the test medium, target pressure or vacuum, stabilization time, measurement method, and pass or fail criteria.

In vehicles and custom builds you will see leak tests across plumbing, compressed air, fuel vapor containment, roof and window seals, and HVAC circuits. In each case, the goal is the same. Prove integrity without overstressing components. A good procedure also records baseline readings so you can compare future checks during maintenance.

The reliability of any leak test depends on four pillars. Appropriate test media, accurate instrumentation, controlled temperature, and a repeatable method. Get those right and results make sense. Skip them and you chase phantom leaks or miss a real one.

Common leak test methods explained

Visual and bubble solution

The bubble method remains a favorite because it is quick and revealing. Pressurize the system with clean dry air or nitrogen, apply a compatible soap solution to joints, and watch for bubble formation. Big bubbles point to gross leaks. Slow foaming suggests minor seepage. Use a low lint brush or spray bottle to avoid introducing debris. Record the pressure, ambient temperature, and the locations inspected so repeats remain consistent.

Pressure decay with a gauge or sensor

Pressure decay measures how fast a sealed system loses pressure over time. After pressurizing to a defined level, allow a short stabilization period as temperature equalizes. Then monitor pressure drop using a calibrated gauge or digital sensor. The acceptance limit is a maximum allowable drop over a set interval. This method works well for pneumatic lines, water systems that can be tested with air, and enclosures. It is sensitive to temperature changes, so perform tests out of direct sun and away from drafts where possible.

Vacuum and smoke diagnostics

Applying vacuum helps reveal leaks that refuse to show under positive pressure. A smoke source creates visible wisps that get drawn into points of ingress. This makes body seams, door seals, and cabin penetrations easy to find. Maintain gentle vacuum to protect thin wall components. Note airflow paths and address the actual source rather than sealing symptoms downstream.

Step by step leak test procedure

The outline below describes a general approach. Always follow system maker limits and use professional grade tools. For flammable or sensitive fluids, use inert gas and dedicated equipment.

Define the scope
List the circuits and joints to validate. Select the method for each, choose test media, and set pass or fail limits based on service pressure and manufacturer guidance.
Inspect before you test
Look for cross threaded fittings, missing O rings, kinked hoses, or surface defects. Fix visible issues first. Clean joints so bubbles or smoke show clearly.
Isolate the system
Cap outlets and close valves as needed. Use blanks rated for the planned pressure. Tag the system so no one runs it while testing.
Connect instrumentation
Install a calibrated gauge or sensor with known accuracy and resolution appropriate to the test. The smallest leak you care about should move the needle in a reasonable time window.
Pressurize or pull vacuum slowly
Use dry air or nitrogen for most pneumatic and water system tests. Raise pressure gradually to the target and hold. For vacuum based checks, evacuate to the planned setpoint and stabilize.
Stabilize temperature
Wait until temperature drift settles. A few minutes is typical for small volumes. Larger systems need longer. Do not skip this step or decay results become meaningless.
Measure and observe
Record the starting reading. Watch for pressure change over the defined interval. Apply bubble solution to suspect joints or run a smoke source as planned. Mark any leak sites.
Diagnose and repair
Confirm the root cause. Replace seals, tighten to spec, or refit the component. Avoid overtightening which can distort soft materials and create new leaks.
Retest and document
Repeat the procedure at the same conditions. Capture pass or fail, test pressure, duration, ambient temperature, and the instruments used. Store this as a baseline for future checks.

Choosing media, limits, and instruments

Test medium

Air or nitrogen suits most structural and plumbing checks because it is clean and controllable.
Avoid oxygen for pressure work to reduce fire risk.
For fuel vapor systems, use inert gas with proper purge procedures.

Test pressure

Use a factor near typical operating pressure, not a random maximum.
For delicate components, a lower pressure plus bubble solution gives safer sensitivity.
Never exceed the lowest rated part in the loop.

Acceptance limits

Set a maximum allowable pressure loss per minute or per test interval.
Tie the limit to function. Potable water lines may allow near zero drop. Exterior body seals may rely on visual smoke confirmation.

Instrumentation

Choose gauges with a full scale that places the test point in the middle third for best readability.
Digital sensors provide fine resolution and easy logging. Calibrate on a schedule.

Safety

Wear eye protection and keep bystanders clear.
Secure hoses and caps to prevent sudden release.
Vent test media safely during disconnection.
Do not pressurize with liquid in a line unless the procedure specifies it.

Finding water ingress in bodies and enclosures

Liquid finds paths that pressure tests may miss, especially at seams and complex curves. Combine methods. First, run a gentle pressure decay to screen for gross leakage. Next, use a smoke source to trace flow paths. Finally, perform a controlled water spray with a consistent pattern while watching from inside with a light. Mark drips, dry the area, correct the seal, and repeat until no ingress appears.

Data that helps future diagnostics

Good records shorten future work. Capture the test date, ambient temperature, relative humidity, method, instruments, target and starting readings, end readings, duration, and results. Photograph leak locations before and after repair. Summarize lessons learned so next time the team knows where to look first.

How this applies to vehicles and vans

Vehicle systems combine rigid lines, flexible hoses, molded tanks, and many joints. Thermal cycling and vibration challenge every seal. That is why a repeatable leak test procedure matters after any modification or build stage. Fuel vapor containment must remain tight. Plumbing must not drip under travel vibration. Cabin seals should resist dust and rain. Address each with the proper method and limits, then verify again at handoff.

At OZK Customs, every completed platform receives a structured validation before delivery. Our team applies pressure decay, bubble solution, vacuum smoke, and water ingress checks where appropriate to confirm real world readiness. If you want a reliable adventure platform, start with repeatable test plans and finish with thorough documentation.

Explore what we build in our Recreational adventure vans. Interested in a one of a kind interior and systems package validated end to end? See our Custom van builds. Looking for a platform that can finance with smart upgrades and a tested handoff? Visit Mainstream vans.

Ready for a sealed and proven build

A high quality build is not finished until the gauges, bubbles, and smoke agree. Bring us your vision and we will design, fabricate, and validate the systems that carry your trips. Our process focuses on safety, function, and clean documentation so you take delivery with confidence. Submit your project details and let us map the leak test procedure that fits your rig.

At the bottom line, OZK Customs designs and delivers recreational adventure vans and overland style upfits with validated plumbing, electrical, HVAC, and seal integrity. Start with our Recreational adventure vans, review our Custom van builds, or explore Mainstream vans to see next steps. Then reach out and we will schedule a discovery call and estimate.