under the bonnet

Now's the time to venture under the bonnet. First have a tentative feel. How warm is the engine? Obviously you don't want to get burnt when feeling around, but how hot it is also tells you how much the car has been run by the seller prior to your arrival. It's always more revealing to start a car from cold. They may only have taken it out of the garage, but be suspicious.

General appearance: all engines are dirty places, but look in particular for oily gunge on the outside the engine, around the engine joins and indications that it may have been splattered about in places where it really shouldn't be - eg. on water bottles or the underside of the bonnet. It could indicate a past leak. Be worried if you see a corroded battery or wires or hoses hanging loose and be suspicious if it's just been steamcleaned. Might be the seller's trying to hide something.

Hoses: try to squeeze the various hoses around the engine bay, particularly those running to the radiator. When squeezed, look closely for cracking or splitting. This shows the hoses are old and need replacing before they split mid-journey and leave you on the hard shoulder. It's also another sign of neglect - clearly the car hasn't been serviced for a while.

Fluids: check all fluid levels. Oil: grab those tissues you brought and take out the dipstick. These usually have a mark to indicate the proper level. The lighter the colour of the oil, the better. Honey-coloured indicates a recent change. Should normally be dark brown or black, but not too dirty and certainly not gritty. Remove the oil filler cap, normally somewhere on the top of the engine, and inspect underneath. White foam indicates water is present in the oil, which is a strong clue to excessive wear and a potential expensive head gasket change. Water: don't remove the radiator cap until the engine has cooled off. Is it full to the proper level? It should be greenish or bluish, not a rusty or milky colour. Green stains on the radiator are signs of pinhole leaks. Squeeze a couple of the radiator hoses and see if the water level moves as you squeeze. Brake fluid: is there fluid to the proper level in the brake fluid reservoir? Power steering: Gearbox: some cars need warming up before checking the gearbox oil. It should be pinkish in colour, not dark brown or black like engine oil. It shouldn't leave metal grit on your rag - a sign of serious problems.

Wiring: feel the plastic outer-coating on electric wires. If it is brittle or cracked, the wires have overheated at some point. Look at the connections between wires - you want to see neat plastic connectors, not joins wound round with black electrical tape.

Belts: feel the fan belt and other belts for tightness and fraying. Do they look worn?

Underneath: use your torch to look up at the engine from under the front.Oil or water drips or leaks aren't a good sign. If you can see where the car is habitually parked - in a garage or on a driveway - check to see if it is covered with puddles or oily stains. If you can see them, examine the constant veolict joints between the front wheels and the engine - normally covered by round, rubber bellows at the end of the axle shafts. If these rubber boots are split or leaking grease, assume the car has, or soon will have, bad CV joints - an expensive repair. Just the rubber boots being split is an MOT failure point.

Look underneath around the rest of the car. Look for leaks around the fuel tank and filler pipe - check for rust, dents and welds in the sills and floorpan, and look at the exhaust. It's bound to be pretty dirty with some light rust, but heavy rust indicates it will soon need replacing. Mention that when it comes to haggling. Look at the residue in the end of the pipe(s) - normal should be dry and dark grey. If black and greasy, the car isn't properly tuned.