Skipping routine maintenance on your Graco® Fusion gun is one of the fastest ways to run into costly problems — from locked-up guns to blistered bed liners. The good news? Two simple checks can prevent most of these headaches before they start.

In this post, you’ll learn:

• How to test your gun for internal leaks before they cause damage
• How to protect the gun nozzle from humidity during shutdown
• Where to get certified Graco products, parts, and expert support

Whether you’re a seasoned installer or newer to spray-on bed liners, adding these steps to your routine will extend the life of your equipment and keep your applications looking clean.

Your Graco® Fusion gun handles two reactive chemicals under high pressure. When the internal components are even slightly compromised, those chemicals can mix where they shouldn’t — causing gun lockups, poor spray patterns, and blistering on the finished liner.

Most equipment failures don’t happen all at once. They start with small, ignored warning signs. The two tips below target those early warning signs directly.

Internal leaks are one of the most common causes of Graco® Fusion gun failure, and they’re easy to miss if you don’t know what to look for.

Turn off the fluid valves below the gun.

1. Pressure up your machine.
2. Turn the air to the gun on, then slowly crack the resin valve.
3. Watch for a mist of air and resin coming from the valve. (It is almost always the side seals part with *issues.)

*Issues that can occur from side seals:
-Defective or wrong size O-Ring installed
-Gunk not removed in O-Ring seat area
-A scratched mixed chamber

What you want to see: clean air only.

What it means if you see mist: you have an internal leak on the resin side. Stop immediately, close the valve, bleed off the machine pressure, and fix the gun before using it again.

Once the resin side checks out, repeat the same process on the ISO side. ISO leaks are especially serious — if any ISO enters the airstream, stop the test right away.

An ISO leak inside the gun needs to be repaired before your next job. No exceptions.

It’s tempting to push through when you’re on a deadline. But that fine mist of resin or ISO can land on the liner during application and cause blistering. It can also travel back into the gun’s internal components, causing premature wear and eventual lockup.

Other signs of an internal leak to watch for:
• Gun grease that looks hard, crusty, or discolored
• Frequently having to rebuild the gun — especially after long weekends or extended downtime
• Inconsistent spray patterns that weren’t there before

If any of these sound familiar, a leak test should be your first step before the next application.

This tip takes about 30 seconds and can save you a significant amount of trouble down the line.

After your last spray of the day, give the gun a small shot of gun grease as part of your normal shutdown process. Then, take a little extra grease and smear it directly over the gun nozzle to create a seal.

That’s it.

The nozzle is an open entry point when the gun is sitting idle. Humid air can travel through the nozzle and come into contact with the ISO inside the gun. ISO reacts with moisture. The moisture in ambient air combined with that reaction can cause buildup, blockages, and internal damage over time.

Sealing the nozzle with grease cuts off that pathway entirely. It’s a low-effort habit that protects the gun between uses, especially in humid climates or during seasonal storage.

Even experienced installers can fall into habits that shorten the life of their equipment. Here are a few things worth checking against your current routine:

• Skipping the leak test before a job — A quick check takes minutes. A locked-up gun mid-job takes much longer to fix.
• Not greasing the nozzle at shutdown — This is easy to forget, but the consequences build up over time.
• Ignoring subtle signs of wear — Hard grease, frequent rebuilds, and mist during testing are all early warnings worth acting on.
• Using non-certified replacement parts — Off-brand or incompatible components can affect performance and may void warranties.

Rhino Linings is a certified distributor of Graco products and parts, which means you have direct access to genuine components, proper replacements, and expert guidance all in one place!

When it’s time to rebuild your gun or replace worn parts, using certified Graco products ensures you’re restoring your equipment to factory specifications. That matters for spray quality, chemical compatibility, and the long-term reliability of your setup.

If you’re not sure which parts you need or you’re troubleshooting an issue you can’t identify, the Rhino Linings technical support team is available to help.

Two checks — a leak test and a nozzle seal — are all it takes to stay ahead of most common Graco® Fusion gun problems. Build them into your routine, and you’ll see fewer equipment failures, better spray results, and longer intervals between rebuilds.

Your next step: Add both of these checks to your shutdown checklist starting today. If you’re already seeing signs of a leak or grease buildup, reach out to the Rhino Linings technical support team before your next job.

Have a question about your spray gun or equipment? Contact the Rhino Linings technical support team directly. If there’s a specific maintenance topic you’d like covered in a future article, send your suggestion to rhinomarketing@rhinolinings.com.

 

Rhino Linings is a certified distributor of Graco products and parts. For replacement components, equipment support, or technical questions, contact your local Rhino Linings representative.

Need More Technical Tips?

Feel free to reach out to the Rhino Linings technical support team with any questions about your spray gun or other equipment. Or, if you’d like to see a specific topic addressed in a future technical article, email rhinomarketing@rhinolinings.com.Quick