Engine replacement checklist: before, during and after fitting

An engine replacement checklist covers three stages: before you order (does the engine code match, which ancillaries come with the engine), before and during installation (fix the cause of the original failure, fresh oil and filter, cooling system, timing belt or chain) and after installation (road test, leak check, oil level). Follow the manufacturer's procedures and keep your paperwork, and your warranty stays fully intact.

Fitting a replacement engine is routine work for most garages. Even so, most problems after a swap are not caused by the engine itself but by details: an ancillary that was not included, a root cause that was never found, a cooling system that was not bled properly. This checklist is written for workshops and for customers who have the job done by a garage. It does not replace the manufacturer's instructions, but it helps make sure nothing important is missed.

Before you order: compare the code and the ancillaries

1. Find the engine code. The replacement must have the same code as the old engine. Matching displacement and power output is not enough, because one engine size often comes in several variants. Our guide how to find your engine code shows where to look.
2. Compare the ancillaries. Read the product description and check the photos carefully: which parts are fitted to the engine you are buying (for example turbocharger, injection system, alternator, air-con compressor, manifolds, wiring loom)? Anything missing has to be transferred from the old engine or sourced separately.
3. Check the condition. Every listing states whether the engine is new, used or remanufactured. This also determines the warranty period.
4. If in doubt, call us. Have the vehicle identification number (VIN) to hand. A quick check before ordering saves a lot of time later.

You can browse all engines or search directly by engine code or OE number.

On delivery: inspect the pallet while the driver is there

Engines and gearboxes are delivered by freight carrier on a pallet, usually within 3–7 working days. The carrier normally phones ahead to arrange delivery. Allow a few minutes for a visual check when it arrives:

• Inspect the pallet and packaging for visible damage before the driver leaves.
• Note any transport damage on the delivery note or consignment note and have the driver countersign it.
• Take photos of the damage and let us know straight away.
• Keep the pallet and strapping: the old unit can go back on it later.

Before installation: find and fix the root cause

This is the single most important point on the list. Engines rarely fail for no reason, and if the cause is not found, the replacement engine will often go the same way. Typical examples:

• Overheating: check the radiator, water pump, thermostat, fan and hoses. If there is oil or sludge in the cooling system, flush it thoroughly.
• Turbo failure: check the turbo oil feed and return lines, and inspect and clean the intercooler and charge pipes for oil and debris.
• Oil starvation or oil pump problems: check the oil cooler and lines for metal particles and clean or replace parts where needed.
• Snapped or jumped timing belt or chain: check tensioners, idlers and guides as well.

Then come the usual preparations: transfer the ancillaries from the old engine to the new one, renew gaskets and seals as you go, check the engine mounts, and inspect or replace the timing belt or chain according to the manufacturer's schedule. If you do not know when it was last changed, replacing it is usually the safe choice.

During installation: oil, coolant and torque settings

• Tighten all fasteners to the manufacturer's torque settings and fit new stretch bolts wherever they are specified.
• Fill with fresh engine oil to the manufacturer's approved specification and fit a new oil filter. Replace the air and fuel filters at the same time if needed.
• Fill the cooling system with the specified coolant and bleed it completely.
• Build up oil pressure before the first start, following the manufacturer's procedure and standard workshop practice.
• Check that all connectors, vacuum hoses and lines are properly secured.

Replacing the gearbox too?

The same principle applies to a replacement gearbox: compare the gearbox code and fill with gearbox oil of the correct specification and quantity. Automatic and DSG gearboxes usually need a basic setting or adaptation with diagnostic equipment after fitting. See our article on faulty DSG gearboxes for more.

After installation: road test, checks and running in

1. Read and clear the fault memory, then check it again.
2. Bring the engine up to operating temperature at idle and check for leaks: oil, coolant, fuel and boost.
3. Once it has cooled down, check the coolant level and top up if needed.
4. Do a road test under varying load, without full throttle. Listen for noises and watch the temperature and warning lights.
5. Take it easy for the first miles: no full load and no high revs while the engine is cold.
6. Check the oil level again after a short time.

Engine replacement checklist at a glance

Keeping your warranty and returning the old unit

New parts (0 km) come with a 24-month warranty, used and remanufactured parts with 12 months, both without a mileage limit. To keep the warranty fully intact, have the engine fitted professionally by a garage and follow the manufacturer's procedures, such as the oil change, bleeding the cooling system and checking the timing belt or chain. Keep your invoice, the engine code, the installation date and the garage invoice. Full details are on our warranty page.

Engines and gearboxes carry a core deposit, usually €500 for engines and €250 for gearboxes; the exact amount is shown on each listing. You get it back when you return the identical, complete old unit, most easily by handing it to the carrier on the same pallet, or by dropping it off in Nortmoor by appointment. Once it has arrived and been checked, the deposit is refunded in full straight away. If you are moving ancillaries from the old engine to the new one, it is best to call us first to agree what needs to come back. More in our article core deposit explained.

Not sure whether an engine will fit or which ancillaries are included? Call us on +49 4950 93890 (Mon–Fri 8:30–12:30 and 13:30–17:30) or email info@motoren-dejong.de. Information on advice, shipping and collection is on our installation and service page.