Pre-trip Vehicle Checks

So, the dates for the next big adventure are booked in and you’re more excited than a kid in a candy store. As with all big trips, your 4WD and camper will need to be mechanically up to scratch in order to make it there and back in one piece.

But how do you know if it’s ready for the long haul? Sure you could drop it to the local mechanic down the road, but how do you know he’s really given it a thorough check-over? The good news is, with a few basic tools and a bit of mechanical know-how you can check out the basics all by yourself — how’s that for peace of mind?

We’ve popped down to pick the brains of Josh from Triple X Offroad, to get the low-down on the quick and easy checks to carry out before you head off.

CHECKING THE BEARINGS

Wheel bearings are one of those things that could stop you dead in your tracks, making them one of the first things to check out. The first thing to check is the free-play. You can do this by jacking up the wheel, putting your hands at the top and bottom of the wheel, and rocking it back and forth for signs of unwanted movement. It’s also a good idea to check the condition of the grease, especially if you’ve tackled any water crossings or bog holes. Also, keep an eye out for diff oil in the hub assembly, as this could indicate the axle seal is damaged.

DIFF BREATHERS

You’ll find a hose with a breather extending from the top of the differential housing. It’s there to let air escape to avoid building up air pressure, damaging the diff seals and causing leaks. One of the first modifications any 4WDer should make is to extend the hoses and mount the breathers in a higher position to prevent any mud from blocking them up. Nonetheless, whether they’re extended or not, it’s worth checking the breathers aren’t blocked by undoing the hose from the diff, blowing compressed air up the hose and checking it blows through the breather.

CHECKING YOUR DIFF OIL

There are few quick and easy checks when it comes to assessing your diff oil. Obviously, the correct oil level is required in order to supply enough lubrication and aid against the build up of heat. If you’ve never checked the diff oil before, start by removing the bung at the back of the diff housing — the oil level should reach the bottom of the bung hole. Poke your pinky in there and check the colour of the oil. In most cases the darker (black) the oil is, the older and less effective it is. Also, if there’s any white or creamy colours mixed with the oil, it’s a good indication that water has found its way in there, which can destroy a diff and bearings in no time at all.

WORN BUSHES

Worn bushes might not seem like the most important repair to carry out, but they are responsible for causing plenty of larger, more expansive breakdowns out on the tracks. The typical bush basically helps absorb any impact. The problem is, a worn bush leaves free-play, and free-play typically means damage when it comes to corrugations and unexpected washouts.

To check the bushes is fairly simple. Start with a visual inspection. Obviously a destroyed bush is going to stand out. But it’s the early warning signs such as minor cracking and flaking that you’ll want to keep a close eye out for.

You can also grab a pry bar, and lever against the bush to see if it’s cracked and can be spread apart. This same method can be used to check everything from panhard bushes to engine mounts.

BRAKE LINE FATIGUE

Now we all know we need to check our brake pads and linings have plenty of meat left on them before a trip, but we often forget the condition of our brake lines. Rubber fatigues over time, so look for cracking, especially around the fitting where it’s often the most strained. Brake lines can also fatigue from the inside out, making it mighty hard to see any visual signs from the outside. So it’s important to replace your brake fluid regularly to avoid aged and contaminated brake fluid from destroying the guts of your brake lines. A great upgrade is to replace the original brake lines with braided lines. They’re much stronger and resistant to damage out on the tracks. Plus, they don’t expand as much under pressure (when you hit the brakes) resulting in a much sturdier pedal feel.

UNIVERSAL JOINTS

Universal joints basically allow the tail shaft to rotate while it’s on different angles. They can develop free-play over time, so should be checked as part of your regular servicing and pre-trip check-ups. As they are part of your drive terrain’s rotating assembly, free-play in the universal joint can throw the balance out of whack and potentially cause vibration when you’re travelling.

The easiest way to check for free-play is to grab either side of the uni joint and rotate your hands in the opposite direction. There should be no free-play at all.

SUSPENSION CHECKS

Four-wheel-drive suspension is a very important part of your tow vehicle. So it’s important to ensure it is set-up for the job at hand. Finding out exactly how your suspension is holding up isn’t easy these days, as the old bouncing-on-one-corner theory doesn’t always apply to modern shock absorber designs. You’ll want to check for any signs of physical damage, as a single dent is enough to disrupt the shaft from sliding up and down smoothly.

A visual check can also help determine if the vehicle is sagging to one side overall. Most 4WDs that have been towing tend to sag in the rear, while others can sag on one side due to unequal load distribution. A fairly simple way to check if your leaf springs for sag is to ensure they’re shaped in a bow as they tend to flatten out over time.

Check out the full feature in issue #89 June 2015 of Camper Trailer Australia magazine.