The N20 and N26 four-cylinder turbo (found in the 3/4/5 Series, X1, X3, and Z4 from roughly 2011–2016) is a chain-driven engine like its bigger inline-six siblings, and shares a similar cold-start rattle warning sign when the chain and guides start to wear. This kit bundles the camshaft locking tools with what you need for flywheel work, since the two jobs are commonly done together when a clutch or DMF comes out.
Tool You'll Need
- Timing & Flywheel Tool Kit — camshaft locking tools plus a flywheel holding tool for N20/N26
You'll also need a crankshaft holding tool, a ratcheting chain tensioner tool, a torque wrench, and the correct chain/guide/tensioner kit for your specific engine code.
Step 1: Confirm the Symptom
A rattle on cold start that fades as oil pressure builds points to chain and guide wear on these engines, same as the larger inline-six family. Confirm via camshaft adaptation values if diagnostic capability is available before committing to a teardown.
Step 2: Establish TDC and Lock the Camshafts
Rotate the crankshaft, counter-held rather than impacted, to Top Dead Center on cylinder 1, then fit the camshaft locking tools from the kit. Both should seat flush and square before you continue.
Step 3: Access the Chain and Tensioner
Remove covers and accessories per your engine's specific procedure to reach the timing chain assembly.
Step 4: Remove the Old Chain Components
Relieve tension carefully with a proper ratcheting tensioner tool — never compress a hydraulic tensioner with raw hand force — and remove the old chain, guides, and tensioner as a full set.
Step 5: Install the New Kit
Fit new guides, a new tensioner in its retracted position, and route the new chain per the factory diagram, keeping the camshaft locks in place the entire time.
Step 6: If You're Also Doing Flywheel Work
With the crank counter-held using the flywheel holding tool from this kit, remove the flywheel bolts per the specified pattern (often a star or criss-cross sequence to avoid warping) and inspect or replace the dual-mass flywheel and clutch as needed while everything's accessible.
Step 7: Release and Verify Timing
Release the tensioner, remove the camshaft locking tools, and rotate the crankshaft through two full turns by hand, returning to TDC. Reinstall the locking tools to confirm correct reference before closing anything up.
Step 8: Reassemble and Test
Reinstall the flywheel (torqued to spec, typically with new stretch bolts), covers, and accessories, then start the engine and confirm the rattle is gone with no fault codes on startup.
Common Mistakes
- Reusing flywheel bolts — these are commonly stretch/torque-to-yield bolts meant for one-time use
- Impacting the crank pulley bolt — always counter-hold
- Compressing the tensioner without pressure relief — risks cracking the plastic guides
- Skipping the two-turn verification — the check that catches a shifted timing before it becomes a running problem
See our full BMW tool lineup for more N20/N26-specific service essentials.