🔥 How to Assemble the Monument Grills Mesa 425

Hey everybody — Aaron here from BBQ by Biggs, and today we’re putting together the Monument Grills Mesa 425, a four-burner propane grill that offers big performance without the big price tag. Whether you’ve already got one sitting in a box or you’re thinking about picking one up, this post walks you step by step through the assembly, tools, and final setup — plus a few tips from the manual that can save you time and frustration.

This grill came packed tight with plenty of protective material. No dents, dings, or surprises out of the box — which is already a win in my book. Let’s walk through it from first cut to final click.

📦 Unboxing & First Impressions

Monument Grills does a great job with packaging. Inside the box, each major part was surrounded by foam or cardboard spacers to prevent shifting or damage. Even thin shelf panels had additional padding underneath. First tip: Save your manual and verify all parts against the included diagram before starting.

🛠️ Tools You'll Need

• Phillips #2 screwdriver (or drill with low torque setting)
• Adjustable wrench (optional for tightening gas fittings)
• Flat surface or table for laying out parts
• Optional: a second person for lifting the grill body onto the frame

🧱 Step-by-Step Assembly Instructions

1. Install the Wheels

Flip the cart base upside down and press the locking caster wheels into place. They should click firmly into the pre-formed holes.

2. Attach the Side Panels

Stand the frame upright. The side panels slide into notched screws already mounted in the base. Loosen them slightly, slide the panel in place, then tighten.

3. Secure the Back Panel

Use hardware labeled “A” and mount the back panel by sliding it into pre-installed screw heads, then securing the lower screws. Everything is clearly labeled in the manual and on the hardware itself.

4. Install the Triangle Supports

Use the screws at the four lower corners to mount the triangle supports — they’ll add rigidity to the base frame.

5. Add the Front Crossbar

Use “F” screws to attach the magnetic front bar. Make sure the magnets face down to catch the grill doors later.

6. Mount the Main Grill Body

This step may require a second person. Carefully lower the main grill body onto the base, aligning the four mounting tabs. Secure with provided screws.

7. Side Shelves & Burner

The right shelf typically contains the side burner. Slide the shelf tabs into place, tighten the set screws, and use two “A” screws (with washers) to secure each side from inside the firebox.

8. LED Knob & Wiring

Feed the LED wiring through the control panel and attach the plastic control knob using two tiny screws. Align flat edge on knob to match the control shaft. Connect black and red wires using the included clips.

9. Install the Regulator

Mount the propane regulator on the side panel and feed the hose beneath the burner assembly. Tighten with a screwdriver and make sure the hose is secure but not pinched.

10. Add Flame Tamers & Grates

Position the flame tamers above each burner, aligning the back notch with the rear edge. Place the cast iron cooking grates — two large on each side, one smaller in the center. Slide in the warming rack and test the lid fit.

11. Install Grease Tray & Doors

Slide in the large rear grease tray and secure it using two “F” screws. Insert the smaller tray underneath. Mount the grill doors by tilting and locking them into the bottom pin, then securing the top latch into the spring clip inside the top rail.

12. Insert Batteries & Test

Install the battery into the LED light control and igniter. Press the igniter to test — you should hear a clean click and see ignition across all burners. Everything should light evenly. If not, check wire connections and alignment.

⚠️ Safety Tips & Burn-Off

• Gas Leak Check: After attaching the propane hose, perform a leak test with soapy water at all connection points. Look for bubbles — never use a flame.
• Pre-Cook Cleaning: Wipe down grates and inner surfaces with warm, soapy water to remove factory dust or oils.
• Burn-Off: Run the grill at 350–400°F for 35–40 minutes with the lid closed. This burns off any residue before cooking food.

📄 Download the Manual

Want to follow along with the official diagrams or verify hardware? Download the Monument Mesa 425 Manual here (PDF).

🎥 Watch the Assembly Step-by-Step

🔥 Final Thoughts

This grill was one of the easiest I’ve put together. Everything fit as expected, the hardware was clearly labeled, and the final result looks clean and solid. From burner alignment to door fitment, nothing needed to be forced or modified — which isn’t always the case with grills in this price range.

If you’ve been thinking about the Mesa 425, I’d say go for it — and if you already picked one up, I hope this walkthrough helped save you some time!

Got questions about this grill or ran into something different during your assembly? Drop a comment and let us know — we’re happy to help and learn together!

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