Exterior check

Rust:

You're are likely to find some rust on an older vehicle. Whether or not it is a major problem depends on the extent of the rust and where it is on the vehicle.

Rust often appears first around the edge of panels, trunks and hoods or on the bottom of door sills.
Structural corrosion (rust on the main structural supports) is dangerous and is a big problem. A vehicle with rust in any of the areas shown in the diagram below is an indication that repairs will be costly.

Look carefully for signs of rust on any of these weight-bearing parts, as well as on the steering mechanism mountings. When you get into the vehicle, look under the carpets, the trunk liner and in the spare tyre area. Another good place to look is inside the door of the petrol cap.

Body rust can be problem too. If the vehicle's paint is bubbling, rust has probably eaten its way through the full thickness of the metal. Of course, a recent bog and paint job may be covering up the problem.

This is where your magnet comes in. When you run the magnet over the car, it won't stick to places that have been filled with bog. Be aware, however, that some crafty bog repairs will pass the magnetic test because the filler has been mixed with iron dust.

Paint:

Does the car look a bit too good? Has it been painted recently? This could mean that paint has been used to cover up recent repairs or rust. Again, you can use your magnet to check for bog.

Have close look at the paint job. A rippled finish can indicate body work underneath. So can different shades of paint on different parts of the car. Look under wheel arches and rubber strips by windows to see if there is over-spray or different colour paint in these places.

Shocks:

Standing at a corner of the car, push it up and down until you have a rhythmic motion happening, then stop. The car should come to the suspension's equilibrium point immediately or within a maximum of one "overshoot". If it doesn't, you might have to replace the shock absorbers. If you can't get an up and down motion happening at all, they definitely need replacing. Repeat this at all four corners.

Stand back and take a look at the whole vehicle, from the front, back and sides. Does it sag down to either side? To the front or back? If so, the springs may be defective.

Tyres:

Check the treads of all the vehicle's tyres, including the spare. Good tyre tread is essential to maintain road grip, especially in wet weather. Legally, treads must be at least 1.5mm deep across 3/4 of the tread pattern, around the entire circumference of the tyre.

Most tyres are required to have tread-wear indicators to show when the depth is less than 1.6mm. In most cases, if the tread is level with these indicators, the tyres will need to be replaced.
Also look for uneven tyre wear, which may indicate problems with the vehicle's steering, suspension or alignment.

Turn the steering to full lock each way in succession and look at the inside of each front tyre. (There will often be damage here that can't be seen with the wheels pointed straight ahead.)

Panels:

Open and shut all the doors, the bonnet and the boot, making sure they are aligned properly and move smoothly. Also check that the windows open and shut easily.

Exhaust:

Look under the car to check out the muffler and exhaust system. Look for soft, brittle areas or use of putty. You can use your magnet to check around this area too.

Use a rag on your hand and plug the end of the exhaust pipe with the engine running - the pressure should build up and blow your hand away from the pipe. If you can keep your hand there without much trouble, there is a leak somewhere in the exhaust system.

An exhaust leak can be very dangerous. If the exhaust finds its way inside the vehicle, carbon monoxide poisoning can result.