A caravan maintenance guide
Giving your van a regular mechanical check-over is essential.
Keeping your caravan in good order is important, so a thorough check of all the mechanicals should be on your regular to-do list. Although I’ve used the term ‘mechanical’ here, what I’m really talking about is the caravan’s moving parts and associated components that help to get you safely and reliably to where you want to go. Sure, a caravan doesn’t have any ‘mechanicals’ in the way of an engine or gearbox, but there’s plenty that can go wrong if you don’t look after it.
A caravan’s running gear is very simple, and it’s often missed maintenance that is the cause of component failure. The trap is to focus too much on the tow vehicle’s maintenance and to forget about the caravan. Even though it is, in many ways, just a trailer chassis, a caravan’s parts wear and, like a poorly-maintained tow tug, it can leave you stranded.
Wear is accelerated when you do a lot of travel on dirt roads or poorly maintained paved roads, and regularly drive through water crossings or in heavy rain. Even if you’re not using your van, some components can, over time, deteriorate enough to require replacement and so need to be checked regularly. Replacing them with fresh parts – none are expensive – as part of regular maintenance is a good idea.
Don’t even attempt to do this maintenance work yourself if you are not confident on the spanners. Caravan maintenance is not difficult but, if you have concerns, then leave the work to a caravan specialist.
GET YOUR BEARINGS
If it has been a few years since they were fitted, fresh, good quality, greased wheel bearings are a good starting point, as bearings are often the first parts to let caravan owners down. Bearings should at least be checked for wear, re-greased and adjusted before any big tour, and it is always a good idea to carry a new spare bearing (pre-greased and sealed in a plastic bag) and a couple of split pins. If you don’t plan any big trips over a 12-month period, then a yearly check is enough.
Only buy good quality bearing brands, such as Timkin, and avoid cheap overseas brands. Make sure the axle spindles are not damaged with score marks when you’re replacing the bearings. You should have greased all through the bearing and not just the outer surface, and the correct tension needs to be applied to the axle nut – some play is necessary. If in doubt, again, get the job done professionally.
Make sure you know your caravan chassis axle-load rating; often it is marked on the chassis manufacturer plate but, if not, use the GTM, which is the maximum allowed mass imposed on the axles. This mass must not be exceeded, otherwise, no matter how new the bearings are you will have problems with them failing, sooner rather than later.
Bearing failure is hard to pick until it’s too late – sometimes they give a warning sign by becoming noisy, but the most likely indication is that the bearing will get hot when it’s about to let go. Brush your hand over the bearing cap when you’ve pulled up for a cuppa and if the bearing cap is too hot to touch, you’re in trouble. Better you find out early rather than when the whole wheel and hub assembly lets go. As you can imagine, if that happens on the road, it is not a pretty sight.
While you’re at the wheels, you can inspect the suspension springs, bushes, spring hangars and dampers (if fitted) for damage (look carefully for cracks in springs and hangars and leaking oil from dampers), and make sure that the suspension is properly greased, if required.
ON THE BRAKES
One of the more common problems out on the road – after bearing issues – is the brakes. You should adjust the brakes so the vehicle and van are sharing the load, and the adjustment at the brake controller will be different for around town versus out on the open road.
The problem is, if you have the brake controller set up to rely too much on the van brakes, they can overheat and cause the brake shoes to score and crack or glaze. If the brakes heat up the hub sufficiently, the wheel bearing grease can boil out and then you have a second problem – a dry bearing, which will eventually seize or fall apart.
A good pre-trip inspection is to check the remaining brake pad or brake shoe material thickness and ensure the brake drums have not scored and that there is no oil or grease on the linings. Replace the pads or shoes if there is any doubt about them lasting the distance of your tour, and get drums replaced or machined if they are scored.
The same applies to brake magnets. While they’re usually reasonably long lasting, they’re relatively cheap to replace if there’s any doubt about their serviceability. One test is to check the magnets’ wires with a voltmeter – they should show 12V with the tow vehicle engine running and the electric brake controller slide applied on full. If there is little or no voltage, there is a problem with the controller or magnets (or wiring) that needs to be chased down and fixed.
OTHER PROBLEM AREAS
When tightening the wheel nuts, make sure the threads are not worn or damaged. If the van is new to you, check the wheel nut mating surface – there should be no paint here as it will cause the wheel nuts to loosen. If there is any paint, be sure to scrape it off.
It’s a good idea to do a shakedown run on a local stretch of highway before the big trip so that you can check all your good work (or that of your mechanic) won’t be undone. Wheel nut tension should be between 120Nm to 130Nm – check this with a torque wrench. And always keep an eye on the tension of the wheel nuts when on tour.
Another potential source of problems is the caravan’s park brake, which you want adjusted up enough to hold the caravan when parked up, but not too tightly adjusted. That said, always chock the wheels as well – no cable park brake operating on drums is totally effective. About 20mm of slack in the park brake cable is about right, depending on the run of cable.
Greasing the coupling is a good idea to stop noise and reduce friction and heat build-up. However, keep in mind you can have problems with securing the coupling if too much grease is applied, or you’ll think it’s secure but the excess grease will mean the locking pin hasn’t engaged and the coupling will detach from the ball when on the move. Use the grease sparingly or, better still, instead use some dry lube on the towball each time you hitch up for a long transport stage. Don’t forget to also lubricate the friction points of the load-levelling hitch, if you use one.
While it is not a mechanical component, caravan wiring is not as durable or long-lasting as most vehicle wiring. It can become weak as it ages and can affect the operation of not only the interior equipment and exterior lights, but also the electric brakes.
Depending on the van and how it is used and stored, you should get over 10 years of reliable operation from the wiring. If the van is older, you might need to consider re-wiring at least the brake and external light systems. While you’re there, increase the wire diameter to reduce voltage drop.
The trailer plug is a common culprit for lighting and electric brake problems. The most common fault is that the pins close up and don’t make good contact with the vehicle’s plug. Check the pins have not closed and, if they have, carefully spread them apart with a thin screwdriver. Don’t get too enthusiastic, though, because the pins are brittle and break easily.
The trailer plug body is not waterproof and, over time, the contacts become corroded. Opening up the plug body and spraying contacts with dielectric grease will help reduce the likelihood of corrosion, but if it has been left too long a new plug might be the go.
Although trailer lights have been much improved with the advent of LEDs, the filament globe type are pretty unsophisticated items that can allow moisture in the unit and corrode connections. Cleaning corrosion off bulb contacts, wiring spade connectors and earth points, and then spraying them with dielectric grease is a good idea before any big trip.
The full feature appeared in Caravan World #552 June 2016. Subscribe today for the latest caravan reviews and news every month!