The two biggest issues are floor rot and frame cracks.
Do a careful visual inspection of the frame, paying special attention around the door and the tongue under the front of the cabin. Surface rust is normal, but deep rust and hairline cracks are not. You may have to brush away surface rust to see whether there are cracks.
Check for floor rot above and below. Look for staining and tap with a blunt object to identify soft spots. Pay special attention inside benches and cabinets around the outer perimeter of the floor, since windows
are the biggest culprit when it comes to leaks
Note the door alignment. Poor door fit is common on older trailers and can be as simple as worn-out hinges. A large gap at the bottom is especially troubling- it can mean a waterlogged inner core, a sagging shell, or a cracked frame.
If you have concerns, try to take some good pictures and post them here. If you have a smartphone, you might download the FiberglassRV app, allowing you to post pictures directly from your camera as you inspect this trailer.
For the axle
, you can check several things.
- Fist test: Make sure there is at least a fist-sized clearance between the top of the tire and the inner wheel well.
- Bounce test: Have someone jump inside the trailer while another person watches for movement of the axle arms behind the wheels.
- Drop test (best): Bring a jack (a scissors jack or, better, a small floor jack) and lift the trailer on each side (on the main frame rail just behind the axle, not on the axle itself). The wheel should drop a couple of inches as the trailer rises. You can check by measuring the distance between the center of the hub to the lip of the wheel arch when on the ground and after lifting.
The cost of an axle replacement seems to vary a lot, but I would expect $600-$900. It's a good time to add brakes
if the trailer doesn't already have them. Places that sell and service utility trailers are your best bet, not an RV repair shop.
For other stuff, the Buyers Checklist
is helpful if you haven't found it already.