I made a checklist for myself when going to inspect a car tomorrow as I know I'll forget things, thought it might be useful for someone else to save them spending an hour typing it out!
Condition of the camshaft and rockers under the valve cover?
Condition of spark plugs? Fouled?
Condition of the radiator/stat?
Condition of hoses - crunchy?
Start from cold - noise?
Does the oil warning light go out as soon as the engine starts?
Are there signs of excessive visible exhaust emissions?
White water vapour from the exhaust is normal while the engine is cold
Blue smoke isn't normal – that's oil burning
Don't worry about faint blue smoke from diesels, but black smoke is serious
Sludge under oil cap or radiator cap?
Condition of dizzy/rotor?
Does it rev cleanly?
How does it idle?
Does the temperature sit at halfway when warm, even after some time at idle, does the auxiliary fan come on (if applicable)?
Is the clutch in good condition? If you hear a noise when you release the clutch in neutral, this could mean the release bearing is worn.
Is the oil level correct? Too low shows neglect; too high could be an indication that the engine is using oil though it may simply have been over filled in error.
Any oil on block etc? Oil pan damaged?
Can the seller show you the V5C or similar vehicle registration document? You won't be able to tax or register the car without it.
Is the seller the registered keeper shown on the V5C (if applicable, UK)? If not, why are they selling it for someone else?
How long has the seller had the car? Short period raises questions or seller could be trader.
Does the registration document have a watermark (if applicable)?
Are there any spelling mistakes on the registration document?
Do the VIN (vehicle identification number), engine number and colour match what's on the V5C/registration?
Does the number plate match what's on the V5C/registration?
Has the VIN plate been tampered with (it should be stamped onto the body on right front side in the engine compartment, and there should be a aluminum ID tag on the same side close to the firewall)
If there are VIN numbers etched on glass are they all the same and do they match those on the VIN plate and V5C/registration?
Can you see deliberate scratches on glass to remove etched-in marks?
Does the seller have a current MOT certificate and certificate of insurance?
Emissions test readings -
Garage / Ramps
1. Compression test.. "Check with a calibrated compression tester, battery fully charged, engine at operating temperature, throttle wide open and at starter speed."
Dry: Cyl1 Cyl2 Cyl3 Cyl4
Wet: Cyl1 Cyl2 Cyl3 Cyl4
Haynes says that below 130psi (9 Bar) is bad ....135-150psi (9.5-10.5 Bar) is average...and above 150psi (10.5 Bar) is good. Over 190 psi (13 Bar) may be high and cause engine pinging depending on fuel spec
2. Condition underneath - chassis: rust, damages, look at floorpan, chassis rails, jacking points, arches, sills, bushes
3. Condition underneath - suspension: front ARB, front arms, rear arms, subframe bushes, steering rack, wheel bearings (rock), suspension leaking, brake lines
4. Other: fuel tanks, fuel lines, sump damage/leakage
B Pillars, front windscreen, rear windscreen, front floor (kickspace rust or leaks), rear floor (rust or leaks), sills, doors (don't forget the bottom), arch edges and inner wings, bumpers (rusty insides), boot surround (seal and rust underneath), door seals, under spare wheel, fuel filler neck, inner wings seen from the trunk
Lights - Hi/Lo, Indicators, Fog, Brake, Hazard Switch
Wipers & washers
If allowed, remove rear seat backing to check for rust
Ask seller to allow you to cold start the engine, check valve cover for warmth in engine before first start
(with cold engine issues will be easier to notice)
Temperature Gauge Behaviour
Oil light flicker
Forward Gears (noise esp)
Steering hard left/right
Hard braking - Any clonks? Pulling to one side?
Edited by Mod (Jeroen)
One last word of advice here: always be suspicious with minor issues. In many cases the seller tells you that an issue you found may be something minor. If it really was a minor issue the seller would have fixed it himself! I've heard many stories already, common examples:
> rattling engine that -according to seller- only requires valve clearances to be adjusted but turning out to be a worn camshaft and warm rockers, a complete cyl head overhaul
> overheating engine that -according seller- only requires a new thermostat or coolant turning out to be a blown head gasket and a ripped cyl head
If you don't trust it or if seller says it's minor, have seller fix it before you buy!