Diagnosing Caravan Problems

Philip Lord — 2 March 2015

Diagnosing caravan problems might seem like a simple thing. After all, aren’t these just trailers with a house thrown on top?

Unfortunately, there is a whole lot more to it than that. So we are going to look at the most common things that go wrong with a van and give you a simple run sheet of things to look out for. Aside from bearings, brakes, tyres and the running lights – which should be checked every time the van is used – the rest of the checks here are really only necessary every six months or so.


The typical caravan chassis is built from boxed-section steel rails with cross beams and an A-frame welded to them. Some have risers, others have an A-frame truss or use C-section steel but all can give trouble. The main thing to look for with a caravan chassis is for damage such as cracking in the steel at stress points or weld points, and damage due to corrosion.

The former is usually due to poor construction and/or overloading and the latter due to long exposure to sea air.

Checking for cracks requires you to look very carefully and methodically at the chassis rails, as they may not be obvious. If the van looks to be sagging in one corner, then it may be the chassis. Some caravans, such as the Viscount Aerolite, are renowned for having problems in this area. If you see chassis cracking, you should seek expert advice as quickly as possible and avoid towing the van.

Corrosion is not often bad enough to do anything but blister under the paint and look unsightly – a quick scrub with a wire brush and a new coat of paint will normally fix that. It is more often the permanent vans on coastal sites exposed to sea air for decades that will have a chassis so badly corroded that it is ready to crumble into a pile of ferrous oxide. If you are looking to buy a van that you suspect has spent a long time by the sea, be very careful.


Caravan suspension is typically a beam axle sprung with leaf springs. Others have coils or torsion bar suspension and the independent trailing arm suspension seen often in newer offroad vans will sometimes have air springs.

Leaf springs can break and this will usually be obvious – the van will sag at that corner. Coil springs tend to be very reliable and, if the coil has broken, it too will be very obvious. In either case, you’ll need expert help to fix the damage and see why it occurred. It is not normal for a van to break a spring – overloading or hitting bumps at high speed might do it. One suspension spring repair I’ve seen on a leaf-spring tandem van was done because the owner’s driveway has a steep angle to it, so when the van was being parked, it would lift one of the axles and all the load would be taken by the other.

Suspension bushes wear out and you can check them for wear by pushing the joint side to side with a screwdriver. It should resist the movement.


Wheel bearings are a common wear point. The only real way of checking these is to jack the wheel off the ground and moving the wheel around to see if there’s any play. If there is movement, it suggests a loose or worn wheel bearing. While you’re there, you can scope the tyres for any abnormal tread wear or damage.

The typical coupling doesn’t cause any grief but, again, it pays to check its condition. If the coupling doesn’t sit tight on the ball, the locking tongue might need to be adjusted up a little. Don’t tighten it too much, or you’ll not be able to release the coupling off the ball. The nuts holding the coupling should be checked for tightness too.

The rear bumper and spare tyre (or tyres) mounting point should be checked for fatigue cracks or damage, and the gas bottle holder also checked for cracks or damage.

Caravan brakes can be difficult to check – they either work or they don’t – so aside from the simple things, such as looking for damaged wiring going to the drums or a closed-up pin in the electrical plug connector, you’ll need a caravan mechanic or auto electrician if your electric brakes are not working. Override cable brakes are really simple to check for damage – the cables should not show evidence of fraying and the pivot point up near the coupling should operate smoothly.


Caravan bodies are either sheeted with aluminium over timber or aluminium, or they have an interlocking composite panel construction. The biggest potential problem any caravan body has is water leaks – it can do a lot of damage very quickly if left unchecked.

Caravans were sealed with a mastic compound before silastic became popular and, over time, this material becomes hard and cracks. This is a perfect breeding ground for water leaks. Check the J moulds and any other sealing point on the van for cracked sealer. If you find any, you’ll need to get the section resealed as soon as you can or risk water damage in the van.

Silastic, if applied properly, should last many years but it too does not last forever. Look for lifting silastic and for discolouration under the silastic – this is a sure sign that water is getting into the join.

Grab a step ladder so that you can take a close look at the roof too – you might find damage up there from a falling branch, for example, that you may have not noticed.

Roof ventilation hatches also should periodically be checked to ensure the seal is not becoming brittle or warped; the same goes for the hopper windows, although these rarely cause trouble.

If the van has been laid up for a while in the weather, check the interior walls and ceiling for water damage. It might be hard to see if it’s dried out since the damage occurred, but if you see any water marks, or smell mould, you need to get the van checked as soon as possible. Water damage is insidious, and can be very expensive to repair if left too long.


Problems with caravan electrics can be difficult to trace. Aside from checking and replacing fuses or blown light globes and that the battery has sufficient charge, your best bet is a caravan repairer or auto electrician.

The one thing you can do is check running lights and taillights – the most common culprit for these not working is either a corroded connection at the globe, a blown globe or the pins at the caravan-to-vehicle plug have closed up, therefore causing a break in the electrical circuit. If some of the pins are completely closed, they can be opened up with a knife. You need to not be over enthusiastic doing this – just a slight gap is necessary. Try to make the gap too large and the cast pin will break off altogether.

The 240V system, of course, must only be worked on by a licensed electrician. The same goes for the gas system. Aside from fitting a new gas cylinder, you must not muck around with gas lines.

Plumbing is usually very simple in a caravan. If you have a water hand pump at the sink rather than a 12V electric water pump to draw from the water tank, then the seals can go hard over time. The result is that the hand pump no longer draws much if any water. You can buy a seal kit – or, for not much more money, a whole new pump. Replacing a hand pump is very easy.


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Denyse Allsop