Ask me what kills an RV and I won't say the engine. It's almost never the engine. It's the eight or nine boxed-in systems nobody looks at until they quit.
We pull apart used coaches for a living. Over a few hundred pre-purchase inspections a year, the same parts die in the same order, and buyers keep getting blindsided because the seller swears "everything works." It worked the day they parked it. That's not the same thing.
So here is the honest order of failure, with the numbers we actually quote when a tech is standing in the driveway.
The systems that fail first, ranked by the bill
Roof and seals lead every list, and we covered that war elsewhere. Set it aside for a second. What surprises people is the order of everything else, because the cheap-looking stuff is what strands you on a Friday night three states from home.
The absorption refrigerator is the quiet champion of expensive failures. Dometic and Norcold both build cooling units that cook themselves if the coach sits unlevel or the rig ages past eight or ten years. When the cooling core leaks ammonia, you don't repair it. You replace the unit, and a residential swap with an inverter runs real money.
| Part | Common failure | Typical repair | Catch it early? |
|---|---|---|---|
| Absorption fridge (Dometic/Norcold) | Cooling unit leaks, stops cooling | $1,500 to $3,500 replaced | Hard. Watch for a yellow stain or ammonia smell. |
| Slide-out mechanism (Schwintek/Lippert) | Motor strips, room racks, won't retract | $600 to $2,500 | Yes. Cycle it ten times and watch the corners. |
| Power converter / inverter | Stops charging the house battery | $250 to $1,200 | Yes. Check charging voltage at the battery. |
| Water heater (Suburban/Atwood) | Tank corrodes, burner board fails | $300 to $1,400 | Yes. Look for rust and a flushed anode rod. |
| Tires (age, not tread) | Sidewall blowout from dry rot | $1,200 to $2,500 a set | Yes. Read the DOT date. Five years, replace. |
| Roof sealant / decking | Leak rots the substrate | $15 to $12,000+ | Yes, and it's the cheapest save on this list. |
Slides are where the money hides
Here's the one people underestimate. A slide-out is a room on rails being pushed by a motor and a few plastic gears. Lippert's Schwintek system, common on lighter coaches, drives the wall on a toothed track. When that track gets dirty or the room gets racked even slightly out of square, the gears strip. Now the room won't come in, and you can't drive.
We cycle every slide ten full times during an inspection. Not once. Ten. A slide that binds on cycle seven is telling you something a single open-and-close will never reveal.
Last spring we looked at a four-year-old fifth wheel the seller called "perfect." The big living-room slide came out fine on the first pull. On the fourth, it groaned and stopped two inches shy of seated. The controller had been masking a failing motor by drawing extra current. Replacement plus alignment came to nineteen hundred dollars. The buyer used the report to take it straight off the price.
The 12-volt side strands more people than the engine
Most RV "breakdowns" aren't mechanical. They're electrical, and they're small. The converter, that gray box that turns shore power into 12-volt charging, fails quietly. You plug in, you assume the battery is charging, and three days into a trip the lights dim and the slides won't move because the house battery is flat.
Test it with a multimeter at the battery terminals. A healthy converter holds around 13.6 volts while charging. Read 12.2 and dropping with shore power connected, and the converter is done. It's a cheap part. It's a miserable surprise.
What this means if you're about to buy
Run the math before you fall in love with the floor plan. A coach can show clean carpet and a waxed exterior and still hide eight thousand dollars of tired systems behind the panels. The sticker doesn't know that. We do, once a tech has hands on it.
If the rig is over eight years old and still wears its original fridge, then budget for a replacement and price it in. If the seller can't produce a tire DOT date under five years, then plan on a set before any long trip. If a slide hesitates even once, then stop and get the mechanism inspected before you sign anything.
Maintenance records beat a wax job every time
The single best predictor of what's about to fail is what the owner ignored. A folder of receipts, anode rods replaced, seals resealed, tires dated, tells us this coach was run by someone who understood it. A spotless rig with no paperwork tells us the opposite, and it usually checks out that way under the panels.
We'd rather buy a slightly scuffed coach with a thick maintenance file than a showroom-shiny one with nothing behind it. So would you, once you've paid for the lesson the hard way.
The parts that fail first are rarely the ones you're staring at. Fridge, slides, converter, water heater, tires. Five systems, and a good independent inspection finds every one of them before money moves. The fifteen-dollar tube of sealant and the four-hundred-dollar inspection are the cheapest insurance in this hobby. Skipping them is how a good deal turns into a project.
If you're shopping a used coach right now, that's exactly what we do. Our inspectors go through every system on this list, and our buyer's agents turn what they find into money off the price. You get the truth in writing before you ever hand over a check.
