Thetford Aria Deluxe 2 Toilet Blade Assembly Installation: Step-by-Step Guide

The Straight Answer

You're absolutely right to question the blade assembly installation on your Thetford Aria Deluxe - the washer placement and assembly orientation are critical for proper sealing. Since your tech replaced the blade mechanism because it wouldn't hold water and you're still experiencing leakage after the repair, the most likely culprit is incorrect washer positioning or the blade assembly not being seated properly against the bowl. The blade assembly has three specific washers that must be installed in the correct order: the large flat washer goes against the bowl bottom, followed by the beveled seal washer (with the bevel facing up toward the mechanism), and finally the spring washer that sits against the blade mechanism housing. Many techs unfamiliar with this specific Thetford model install the beveled washer upside down or omit the spring washer entirely, which creates the exact leaking issue you're experiencing now.

Your instinct to pull the assembly back out is spot-on because getting this right the first time prevents having to drain and disassemble everything again later. The blade assembly should sit flush against the bowl with no gaps, and when you manually operate the blade from inside the bowl, it should create a smooth, complete seal around the entire circumference. If there's any rocking, tilting, or if you can see daylight through any part of the seal when the blade is closed, the washers are definitely in the wrong position or the assembly isn't properly aligned.

Breaking It Down

Let's talk about what's really happening with your Aria Deluxe 2 and why this particular repair can be so frustrating. Thetford designed this toilet with a specific blade mechanism that creates a water seal by pressing a rubber blade assembly against the bowl bottom. The entire system relies on precise washer placement and proper compression to maintain that seal. When your original blade wouldn't hold water, it was likely due to warped or deteriorated washers rather than the blade mechanism itself, but replacing the entire assembly was probably the right call since those washers aren't sold separately.

The tricky part about this repair is that the Aria Deluxe 2 uses a three-washer system that many people, including some RV techs, don't fully understand. The bottom washer creates the primary seal against the bowl, the middle beveled washer provides angular compensation for any slight bowl irregularities, and the top spring washer maintains proper compression on the entire stack. Each washer has a specific orientation and purpose, and getting any of them wrong results in exactly what you're experiencing - continued leaking even with a brand new blade assembly.

Your tech likely installed the new blade assembly mechanism correctly from a mechanical standpoint, but the devil is in the details with the washer stack. I've seen this exact scenario dozens of times where the repair itself is done properly, but the final sealing components aren't positioned correctly. The good news is that you've already done the hard part by getting the toilet apart and the old mechanism out. Reassembling it correctly is much easier once you know the proper sequence.

Another factor that could be causing your leak is the bowl condition itself. If the previous blade assembly was leaking for an extended period, mineral deposits or calcium buildup might have created an uneven surface where the washers need to seal. Even with perfect washer placement, an irregular bowl bottom won't allow proper sealing. This is why it's crucial to thoroughly clean and inspect the bowl sealing surface before installing the new assembly.

What You Need

Since you've already got the toilet disassembled and the new blade assembly ready to install, your tool requirements are minimal but specific. You'll need a good flashlight or headlamp to clearly see the washer orientation - this repair happens in a confined space under the toilet where lighting is always challenging. A small mirror can be incredibly helpful for checking the washer placement from different angles, especially to verify that the beveled washer is oriented correctly.

For cleaning the bowl sealing surface, you'll want a plastic scraper to remove any mineral buildup or old sealant residue. White vinegar or CLR (Calcium, Lime & Rust remover) works well for dissolving stubborn deposits. Don't use anything abrasive that might scratch the porcelain, as even small scratches can prevent proper sealing. A clean rag and some degreasing cleaner will help ensure the surface is completely clean before assembly.

You should have received three washers with your new blade assembly: a large flat rubber washer (usually black), a beveled rubber washer (often gray or brown with one angled side), and a spring washer or wave washer (thin metal with a wavy profile). If your kit didn't include all three washers, or if any of them look damaged, order the appropriate seal kit from Thetford (consult manufacturer specs for correct part number). Don't try to reuse old washers or substitute washers from other applications - the tolerances are too specific.

For the actual installation, you'll need basic hand tools: a screwdriver set, adjustable wrench, and possibly a socket set depending on your specific model year. Have some plumber's grease or marine-grade waterproof grease available to lightly coat the washers during installation. This isn't always necessary, but it helps ensure proper seating and makes future disassembly easier. Keep a bucket and towels handy since there will likely be some residual water in the system even after draining.

Doing the Work

Start by thoroughly cleaning the bowl bottom where the blade assembly will seal. This surface must be perfectly clean and smooth for proper sealing. Use your scraper to remove any mineral deposits, old sealant, or rough spots. The sealing surface should feel smooth to your finger when you run it around the circumference. Pay special attention to the area where the old assembly was leaking - there might be more buildup there. After mechanical cleaning, wipe the entire surface with CLR or vinegar to dissolve any remaining deposits, then dry completely.

Now comes the critical part - washer installation. The correct order from the bowl bottom up is: large flat washer first (against the bowl), beveled washer second (with the thick edge facing up toward the mechanism), and spring washer third (against the blade mechanism housing). The large flat washer should sit perfectly flush against the clean bowl bottom with no gaps or raised areas. If it doesn't lie flat, there's still contamination on the bowl surface that needs to be cleaned.

The beveled washer is where most installations go wrong. This washer has one thick edge and one thin edge, creating an angled profile. The thick edge must face up toward the blade mechanism, with the thin edge sitting on top of the flat washer. Installing this washer upside down is probably the most common cause of continued leaking after blade assembly replacement. Take a close look at the washer profile before installation - when installed correctly, it should create a slight funnel shape with the narrow end pointing down toward the bowl.

Position the blade mechanism on top of the washer stack and check that everything aligns properly before tightening any bolts. The mechanism should sit level and stable with no rocking or tilting. If it's not stable, one of the washers is probably out of position. With the mechanism properly positioned, install the mounting bolts finger-tight first to ensure proper thread engagement. The spring washer will compress slightly as you tighten the bolts, creating the proper sealing pressure on the entire washer stack.

Tighten the mounting bolts evenly in a cross pattern to ensure even pressure distribution on the washer stack. cross pattern according to manufacturer torque specifications in a cross pattern, similar to mounting a tire. Don't overtighten - you want firm compression on the washers without crushing them. Most Aria Deluxe 2 installations require about 10-12 foot-pounds of torque, which is firm hand-tight with a standard screwdriver. Over-tightening can actually cause leaks by deforming the washers or cracking the porcelain bowl.

Before reassembling the toilet completely, test the blade operation from inside the bowl. The blade should move smoothly and create a complete seal around the entire circumference when closed. You shouldn't be able to see any light through the seal, and there shouldn't be any areas where the blade doesn't contact the bowl surface. If the blade binds or doesn't seal completely in any area, disassemble and check your washer installation again.

Time for a Pro

While this repair is definitely within the capabilities of most DIY RV owners, there are specific situations where calling a professional makes more sense than continuing to troubleshoot on your own. If you've followed the correct washer installation procedure twice and you're still experiencing leaks, the problem might be more complex than simple assembly issues. A cracked toilet bowl, warped mounting flange, or damaged floor structure could be preventing proper sealing regardless of how perfectly you install the washers.

Professional diagnosis becomes valuable when you're dealing with multiple toilet issues simultaneously. For example, if your Aria Deluxe 2 is also having flushing problems, water level issues, or the pedal mechanism is malfunctioning, these interconnected problems might indicate deeper issues with the toilet's internal systems or the RV's plumbing connections. An experienced RV technician can quickly identify whether you're dealing with individual component failures or systemic problems that require more comprehensive repairs.

Consider professional help if you discover that the toilet bowl itself is damaged during your inspection. Hairline cracks in the porcelain, chips around the sealing surface, or any structural damage to the bowl mounting area typically require toilet replacement rather than component repair. These issues aren't always obvious to untrained eyes, and attempting repairs on a damaged bowl often leads to bigger problems including water damage to the RV floor structure.

The cost consideration also matters when deciding between DIY and professional repair. A complete blade assembly replacement by an RV service center typically runs $200-350 including parts and labor. If you've already purchased the blade assembly and invested significant time in the repair, spending another $100-150 for professional installation might be worthwhile to ensure it's done correctly. This is especially true if you're not comfortable with the disassembly process or if your RV is still under warranty where improper repairs might void coverage.

Finally, don't hesitate to call for help if you encounter any surprises during disassembly that weren't part of the original repair plan. Sometimes removing a toilet reveals other issues like rotted flooring, corroded mounting bolts, or plumbing problems that require different expertise and tools. Professional RV technicians deal with these complications regularly and can often address multiple issues during a single service call, potentially saving you time and money in the long run.