You don't need to be a mechanic to spot the early warning signs that something underneath your van needs attention. Catching a bearing or brake issue early is the difference between a $200 service and a $5000 roadside disaster. Here's what to look for and what to leave to a professional.

The Pre-Trip 10-Minute Walk-Around

Before any trip — especially after the van has been sitting for a while — walk around it and check the following:

Tyres

• All inflated to your travel pressure (cold check, not after towing)
• No bulges in the sidewalls
• No cracking in the rubber (UV damage)
• Tread depth — both visually even side-to-side and front-to-back, and minimum 1.5mm legal depth (most caravan owners replace well before this)
• Date code on the sidewall — tyres older than 6 years should be inspected even if they look fine; older than 10 years should generally be replaced

Wheel Nuts

• Visually intact — none missing, none obviously loose
• If the van has done less than 500km since wheel work (service, rotation, replacement), check torque with a torque wrench
• See the existing help centre article Wheel Nuts Re-Check Explanation for the full process

Brakes (Visual)

• No fluid or grease visible behind the wheel (could indicate seal failure)
• Brake controller in the tow vehicle showing the right signal when you tap brakes
• No metallic screeching when you do a low-speed test brake

Suspension

• Visible damage to springs, shocks or airbags
• Excessive sag on one side compared to the other
• Any signs of oil leak from shocks (a small mist is normal; running oil isn't)

Hub Area

• Smell — burning grease smell after towing = bearing issue
• Touch — carefully feel the hub temperature after a short tow. Warm is fine. Too hot to touch is a problem.
• Sight — any grease leaking from behind the wheel

Wheel Bearings — The Most Critical Service Item Underneath

Why They Matter

Bearings let the wheel spin freely on the axle. They're packed with grease and sealed. When they fail, the failure progresses fast — you can go from "slightly grumbly" to "wheel falls off" in a few hours of high-speed towing.

Service Interval

Most caravan bearings need inspection, repack and seal replacement every 12 months or 20,000km — whichever comes first. Off-road and dusty/wet use shortens this interval significantly. A bearing service for the whole van is typically $300–$600.

Warning Signs (Stop and Inspect Immediately)

• Hub hot to the touch after towing (the wheel itself should be ambient or barely warm; the hub centre can be warm but not painful to touch)
• Grinding, rumbling or whining noise that changes with wheel speed
• Wheel wobble side-to-side when jacked up and grabbed top-and-bottom
• Grease leaking from behind the wheel
• Brake dust on one wheel dramatically different from the others

If You Suspect a Bearing on the Road

1. Pull over safely.
2. Let everything cool — 20+ minutes.
3. Inspect the wheel: temperature, leaks, free play (grab top and bottom of the tyre, try to wobble — there should be almost none).
4. If anything is concerning, call for roadside assistance or a mobile mechanic. Don't keep towing on a suspect bearing.
5. Failed bearings are usually replaceable on the side of the road by a mobile mechanic if you can get one to you.

Brakes — Electric Braking Basics

Mars caravans use electric brakes that are activated by the brake controller in your tow vehicle. The controller sends a signal proportional to your brake pedal pressure, and the caravan brakes apply.

Adjustment

Brake controllers have a gain setting that determines how hard the caravan brakes pull. Too low = the van pushes the vehicle; too high = the van locks up. Adjust:

• On a clear empty road at 40 km/h, press the manual override on the controller (slides usually).
• Vehicle should slow without the wheels locking and without you feeling a strong push from behind.
• If wheels lock — gain too high.
• If you feel the van pushing — gain too low.
• See existing help centre article Brake Controller Setup + First Drive Checks.

Warning Signs

• Van pulling to one side under braking (uneven brake application)
• Caravan brakes feel weaker than normal
• Grinding or screeching under braking
• Brake controller showing fault codes
• Smell of hot brakes after a normal descent

Service Interval

Brake inspection at every annual service. Components (magnets, shoes, drums) wear at different rates depending on use — off-road, mountain country and heavy braking accelerate wear. Plan for brake shoe replacement every 30,000–60,000 km depending on use.

Suspension — Independent Coil or Airbag (Most Mars Models)

What Wears

• Shock absorbers — 50,000–80,000 km typical life on a caravan, less if off-road regularly. Worn shocks = bouncier ride and shorter tyre life.
• Bushes — rubber/poly components in the suspension wear over years rather than km. Inspect at service.
• Coil springs — long-life, but can sag over time or break in rare cases.
• Airbags — if your van has airbag suspension, the bags themselves can fail (leaks, abrasion). Compressor too.

Warning Signs

• Van "porpoising" (bouncing nose-up nose-down) on bumps
• Excessive lean in turns
• One side noticeably lower than the other when parked level
• Oil running from shock absorbers
• Clunking sounds over bumps
• Airbag system: not maintaining ride height, compressor running constantly

What's Owner DIY vs Professional

Owner Can Do

• Visual inspections
• Wheel nut torque check (with torque wrench)
• Tyre pressure checks and adjustments
• Reporting suspected issues to service centre

Professional Only

• Bearing inspection, repack, replacement
• Brake adjustment and replacement
• Shock absorber replacement
• Suspension bush replacement
• Airbag system service
• Anything involving disassembly of structural components

Service Schedule Summary

Beyond your daily walk-around, the maintenance schedule is roughly:

• Every trip: walk-around inspection (10 min)
• Every 1000km of towing: visual check of hub temperatures after a long day
• Every 12 months or 20,000km: full annual service including bearings, brakes, suspension
• Annually for off-road use: consider mid-year bearing inspection if you do significant dusty or wet work
• After serious off-road use: inspect bearings, brakes and suspension after returning
• After any creek crossing: inspect bearings — water contamination is a common cause of premature bearing failure

See existing help centre article Mars Caravan Service & Maintenance Schedule for the full list.

The 30-Second Habit

After every stop on a tow day, walk around the van and feel each hub. Warm = fine. Significantly hotter than the others = stop and investigate. This single habit has saved more caravans from roadside disasters than any other maintenance check.

Related: Mars Caravan Service & Maintenance Schedule · Wheel Nuts Re-Check Explanation · Brake Controller Setup· First 500km Safety Checklist