How Long Does It Take to Replace a Car Engine?

Quick Answer

A full engine replacement takes 8–20 hours of labour, which translates to roughly 2–5 days at a typical repair shop. The wide range reflects differences in vehicle complexity, engine type, and whether the replacement is a direct swap or a conversion to a different engine.

Engine Replacement Timelines

Scenario	Labour Hours	Calendar Time	Notes
Same-model engine swap (common car)	8–12 hours	2–3 days	Straightforward bolt-in replacement
Same-model engine swap (luxury/performance)	12–18 hours	3–5 days	More complex routing and electronics
Different engine swap (conversion)	20–40+ hours	1–3 weeks	Custom fabrication may be needed
Remanufactured/crate engine install	10–15 hours	2–4 days	Pre-assembled; reduces some labour
Classic car engine rebuild in-place	15–25 hours	3–7 days	Disassembly, machining, reassembly

What the Process Involves

Step 1: Diagnosis and preparation (1–2 hours)

The technician confirms the engine needs replacement, orders the replacement engine, and prepares the workspace. Parts sourcing can add days or weeks to the total timeline if the engine is not readily available.

Step 2: Removal of the old engine (3–6 hours)

This involves disconnecting the battery, draining fluids, removing the radiator, disconnecting exhaust manifolds, unbolting engine mounts, detaching the transmission (or removing it together with the engine), and lifting the engine out with a hoist or crane.

Step 3: Transferring components (2–4 hours)

Many parts from the old engine are transferred to the replacement, including the alternator, starter, intake manifold, exhaust manifolds, engine mounts, sensors, and wiring harness connectors. This step is critical for ensuring compatibility.

Step 4: Installing the replacement engine (3–6 hours)

The new engine is lowered into the engine bay, bolted to the transmission, and connected to all mounts. All fluid lines, electrical connections, coolant hoses, and exhaust components are reattached.

Step 5: Testing and break-in (1–2 hours)

The technician fills all fluids, checks for leaks, programs the ECU if needed, and performs a test drive. Some replacement engines require a break-in period of 500–1,000 miles with gentle driving.

Factors That Affect Timeline

Vehicle type has the largest impact. A straightforward 4-cylinder sedan takes far less time than a turbocharged, all-wheel-drive vehicle with complex wiring and tight engine bay packaging.

Parts availability can be the biggest bottleneck. A common engine for a popular model may be in stock at a salvage yard, while a low-production or imported engine could take weeks to source and ship.

Shop workload affects calendar time. Even if the job takes 12 labour hours, a busy shop may spread this across 3–5 business days as technicians juggle multiple vehicles.

Engine source matters. A remanufactured or crate engine from the manufacturer comes pre-assembled and tested, reducing install time. A used engine from a salvage yard may need inspection and component swaps before installation.

Cost Breakdown

Component	Cost Range
Replacement engine (used)	$1,500–$4,000
Replacement engine (remanufactured)	$2,500–$7,000
Replacement engine (new/crate)	$4,000–$10,000+
Labour (8–20 hours at $100–$150/hr)	$800–$3,000
Fluids, gaskets, and misc. parts	$200–$500
Total	$2,500–$13,500

Tips for a Smooth Engine Replacement

• Get a written estimate that separates parts and labour costs.
• Ask about the warranty on the replacement engine – remanufactured engines often come with 12–36-month warranties.
• Request the old engine back (or at least photos) to verify the replacement was necessary.
• Follow break-in procedures carefully to ensure the longevity of your new engine.

Summary

A standard engine replacement takes 2–5 days at a repair shop, with 8–20 hours of actual labour. Parts availability and vehicle complexity are the biggest variables. Budget $2,500–$13,500 depending on the engine source and vehicle type.