Used bus inspection checklist: what to check before buying

On a used bus you check the paperwork first and the mechanics second: chassis number match, mileage, service history, engine, gearbox, brakes, air system, suspension, rust and electronics. The checklist below follows the order in which an inspection runs in practice, with a cold engine at the start and a road test at the end.

We at HellasBus have been buying, inspecting and reselling buses since 2009, from Citaro city buses to three-axle coaches. The mistakes that cost the most are rarely hidden. Usually they are things the buyer saw but didn’t look into.

Which documents should you check first on a used bus?

First check that the chassis number (VIN) on the vehicle matches the registration certificate and that the year, seats and emission class agree. Then ask for the service and KTEO (the Greek roadworthiness test) history.

If the bus is imported, also ask for the documents from the country of origin. Anything missing from the file is something you will have to chase at registration.

How do you check the mileage on a used bus?

You check the mileage by cross-referencing the odometer, service invoices, KTEO records and the digital tachograph. The digital tachograph, required under Regulation (EU) No 165/2014, records the odometer reading, so a single download shows whether the numbers agree.

Wear tells its own story too. A polished steering wheel, a worn driver’s seat and pedals with the rubber gone don’t fit with 200,000 km on a 15-year-old bus. A city bus that worked a route makes many stops and opens its doors thousands of times. That is why, on a city bus, the doors and brakes say more than the figure on the odometer.

What do you check on the engine during a cold start?

Start the engine cold, after it has stood for hours, and watch for smoke, noise and oil pressure. A warm engine hides hard starting, knocking and leaks.

• Blue smoke: it is burning oil, from the piston rings, valve stem seals or turbocharger.
• White smoke that doesn’t clear: possibly water in the combustion chamber, meaning the head gasket or cylinder head.
• Black smoke under throttle: injectors, turbocharger or air filter.
• Fumes from the oil filler cap: with the engine idling, remove the cap. Strong blow-by indicates wear.

Check the level and colour of the oil and coolant. Milky-looking oil, or oil in the coolant reservoir, is a reason to stop the inspection. Look over the engine bay for oil and fuel residue as well. On the first-generation Citaro, for example, engine-bay fires were recorded and recalls followed, with Daimler linking the risk to oil and fuel residue and to poor maintenance. A clean engine bay is a safety matter. Read more in our article on the Mercedes-Benz Citaro.

How do you check the gearbox and retarder?

The gearbox is checked on the test drive. Shifts should be smooth, without jolts, slipping or delay, both uphill and downhill. On automatic gearboxes also ask when the oil was last changed, because changing it at the right interval keeps the gearbox alive.

The retarder (hydrodynamic brake) is tested on a descent. It should scrub off speed noticeably and steadily without pushing the coolant temperature too high. A retarder that doesn’t work means the brakes have done all the work on descents, so check them more carefully.

What do you check on the brakes, air system and suspension?

On the air system, check how quickly it fills, whether it holds pressure with the engine off and whether the air dryer has been replaced on schedule. On the brakes, look at pad thickness and the discs, and on the air suspension, check that the vehicle levels itself.

1. Empty the system, start the engine and time how long it takes for the low-pressure warning to go out.
2. Switch off the engine and listen for air leaks. After a few minutes the pressure should stay almost constant.
3. Open the drain valves on the air tanks. Water or oil points to a tired air dryer or compressor.
4. Check the suspension air bags for cracks and the ride height after the bus has stood for an hour.
5. On low-floor city buses, test the kneeling function and the wheelchair ramp.

Where do you look for rust on a bus?

Look for rust on the underside of the frame, around the doors, in the wheel arches and at the floor joints. Rust in the load-bearing frame costs far more than rust on an outer panel.

You need a pit or a lift and a torch. Press down on the floor near the doors and under the seats. A soft floor means water has been getting in for years. On city buses, which are washed often and work through winters with salted roads, this is the most important check of all.

Which electronics and equipment need checking?

Run a diagnostic check for stored fault codes and test every system the passengers use: doors, air conditioning, heating, destination displays, microphone, and the fridge and toilet where fitted. Air conditioning is one of the most expensive systems to repair.

AdBlue is a 32.5% urea solution. If it is contaminated or old, the SCR system logs faults and the engine may lose power. What changes from one emission class to the next is explained in Euro 5, EEV or Euro 6.

What do you check in the passenger area and luggage bays?

In the passenger area check the seats, seat belts, floor, windows and lighting, because these are what your customers see from day one. On coaches, open every luggage bay and check the locks, seals and for damp.

Count the seats and compare them with the number on the registration certificate. A bus whose layout was changed without the documents being updated will cause you trouble at KTEO. On coaches, check that the seats recline and lock, that the belts retract properly and that the toilet, if fitted, has tanks with no leaks. A musty smell in the luggage bays or under the seats usually means water coming in through the windows or from the roof-mounted air conditioning.

How do you set up the test drive?

The test drive needs at least 20 minutes, with town driving, an uphill, a downhill and a stretch at steady speed. Drive it yourself or have your driver do it, and take notes.

• Steering: straight, with no play and no pulling under braking.
• Noises: humming from the differential or wheel bearings, knocks from the suspension over speed bumps.
• Temperature: steady, even with the retarder in use.
• After the drive: check under the vehicle for leaks again.

What do you do with what the inspection found?

Write down every finding with its cost and priority. Anything affecting safety or KTEO is fixed before delivery, and the rest goes into the negotiation. Ask for everything you agree to be written into the purchase agreement.

All HellasBus buses stand at our premises in Litochoro, Pieria, and you can carry out this inspection on site, with your own mechanic if you wish. See the buses available now, read the complete buying guide or call +30 23520 61222 to book a visit.