The Bush Mechanic Guide: 7 Essential 4WD Fixes to Get You Going Again

The Bush Mechanic’s Mindset: The 3 P’s

1. Prevention: Before trips, do a bolt-and-fluid inspection on both 4WD and trailer. Belts, hoses, clamps, bearings, brake lines, wiring looms, hitch bolts, U-bolts, shackle bushes—fix anything marginal.
2. Preparation: Quality socket set, ring spanners, tyre plug kit, compressor, multimeter/test light, spare fuses/relays, duct/electrical/self-amalgamating tapes, cable ties, mechanic’s wire, hose clamps, two-part epoxy putty, silicone sealant, spare wheel nuts/studs, bearing grease, spare bearings & seals.
3. Practice: Don’t open a kit for the first time on a dark, rainy track. Practice plugging tyres, using the multimeter, and packing bearings at home.

Part 1 — Trip-Stopper Fixes (get these wrong and you’re staying put)

1) Punctures

Off-road = punctures. Modern tyres are tough, but rocks, stakes, nails and thorns still win sometimes. Extra spares are great; a plug kit is better.

1. Find the leak (soapy water spray is quickest).
2. Ream/rough the hole—firm pressure helps the plug bond.
3. Coat plug with rubber cement; insert until tails show.
4. Twist/pull tool, let set, trim tails, reinflate and bubble-check.
5. Monitor during the trip and get a professional patch later.

2) Cooling system leaks (the dreaded hiss)

Coolant loss can cook an engine. Common culprits: split hoses, stick-damaged radiators.

Hose repair: Cool completely → dry area → wrap self-amalgamating silicone tape under stretch → add a duct-tape jacket → top up and monitor.

Radiator weep/crack: Pinholes: stop-leak pellets (or a pinch of black pepper) can limp you out. Bigger cracks: drain below damage, clean and rough the surface, press on epoxy putty, allow to cure.

3) Fuel & water tank leaks (the puddle)

Fuel leaks are fire risks; water leaks can be trip-ending in arid country.

1. Reduce flow (tilt vehicle/trailer if safe).
2. Clean aggressively (brake cleaner/metho), rough the area.
3. Knead two-part epoxy and force it over the hole, feather edges.
4. Let cure as long as possible before moving.

4) Snapped suspension & drivetrain (the clang)

Corrugations + heavy loads = metal fatigue. Typical failures: trailer leaf U-bolts, shock eyelets, sway-bar links, shackle bolts.

• U-bolt broken: Best fix is a spare set. As a last-resort limp, two high-strength ratchet straps can hold axle to spring pack at walking pace to reach a safe repair spot.
• Shock eyelet/mount gone: Tie the shock body up to the chassis with fencing wire/heavy cable ties so it can’t whip brake lines. Reduce speed.

Part 2 — Sanity-Saver Fixes (won’t strand you, but will wreck your mood)

5) Rattles

Corrugations shake everything. Prime suspects: jockey wheel, roof-rack hardware, skid plates, battery clamps, stone guards.

Fix: Re-torque, add blue threadlocker, wedge with rubber, tension with bungees, or secure with zip-ties until a proper repair. A smear of grease inside a sloppy jockey wheel calms the noise.

6) Leaky tents & awnings (the midnight drip)

In the storm: Dry the inside area and slap on duct tape to get through the night.

Next day: Dry thoroughly and apply a proper canvas patch or seam sealer.

7) Electrical gremlins (the click)

No-start vehicle: Clean/tighten battery terminals → check main fuses/relays with a test light/multimeter.

Trailer lights dead: Open the 7-pin, clean mud/corrosion, reseat pins. Confirm earth strap attaches to clean, bare metal. Carry spare bulbs/fuses.

Trailer-specific quick fixes (worth knowing cold)

Quick-reference: tools & spares kit

Pre-trip prevention checklist (15-minute walk-around)

• Tyres: condition, pressures (including trailer), torque wheel nuts as per vehicle/trailer spec.
• Fluids: oil, coolant, brake, power steering; look for fresh drips underneath.
• Suspension: inspect U-bolts, shackle bushes, shock mounts for cracks/looseness.
• Brakes: pedal feel, trailer brake function test, look for chafed lines.
• Wiring: secure looms away from sharp edges; test all lights including trailer.
• Hitch: tongue pin, coupling latch, breakaway cable, chains and D-shackles.
• Load: weight distribution and tie-downs; heavy gear low and centered.

Bush Mechanic FAQ

What’s the one tool I should never leave without?

A quality tyre plug kit and a reliable compressor. A puncture is the most common “trip-stopper” you’ll face, and it’s also one of the easiest to fix on the trail if you have the right gear. Everything else can often be limped, but a flat tyre stops you dead.

Can I really fix a radiator leak with epoxy putty?

Yes, as a temporary trail fix to get you home. The key is meticulous prep: the surface must be clean, dry, and roughed up (sanded) for the epoxy to bond properly. It’s a “limp-home” repair, not a permanent solution.

My 12V fridge keeps cutting out. What’s the first thing to check?

Check your connections, not your battery. 90% of 12V gremlins are a poor connection. Anderson plugs get filled with dust and mud. Cigarette-style plugs vibrate loose. Most importantly, check your earth strap—ensure it’s bolted tightly to a clean, bare-metal spot on the chassis or body.

Is it worth carrying spare U-bolts for my trailer?

If you are towing a leaf-sprung trailer on heavy, corrugated tracks, absolutely. They are a common failure point. A spare U-bolt, nuts, and a large spanner weigh little but can save your entire trip.

What’s the difference between a static strap and a kinetic rope?

This guide focuses on fixes, not recoveries. A static strap (like a tow rope) has no stretch and is used for a gentle, controlled pull on firm ground—like towing a disabled vehicle. A kinetic rope (or snatch strap) is an elastic band designed to stretch and is used to recover a vehicle bogged in sand or mud. Never use a kinetic rope for a simple tow.