The M157, M276, and M278 twin-turbo V6/V8 engines add a wrinkle beyond a standard chain job: direct injection means you're also potentially dealing with injectors that need to come out for related work, alongside the usual multi-cam locking job. This kit bundles both needs — alignment/locking bars for the camshafts and an injector puller — because on these engines the two jobs tend to overlap.
Tool You'll Need
- Engine Alignment & Locking Timing Tool Kit (T60/T100 + Injector Puller) — camshaft locking bars, alignment plates, and an injector puller in one kit
You'll also need a crankshaft holding tool, a torque wrench, and the correct chain/guide/tensioner kit, plus new injector seals if you're pulling injectors as part of the same job.
Step 1: Establish TDC and Lock the Camshafts
Bring the crankshaft to Top Dead Center, counter-held rather than impacted, then fit the locking bars from the alignment kit across the camshafts on the bank(s) you're working. Confirm each seats flush before continuing.
Step 2: Access the Chain and, If Needed, the Injectors
Remove covers and accessories per your engine's specific procedure. If your job also involves injector service, this is typically the point where you'd pull them — using the puller from the same kit rather than prying against the head.
Step 3: Remove Old Chain Components
Using a proper ratcheting tensioner tool, relieve tension carefully and remove the old chain, guides, and tensioner as a full set.
Step 4: Install New Components
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 throughout.
Step 5: Reinstall Injectors If Removed
If injectors came out, fit them with new seals per the kit's puller/installer procedure — never reuse a compromised seal on a direct-injection system, since a poor seal here affects combustion, not just a slow leak.
Step 6: Release and Verify Timing
Release the tensioner, remove the locking bars, and rotate the crankshaft through two full turns by hand, returning to TDC. Reinstall the locking bars to confirm correct reference before closing anything up.
Step 7: Reassemble and Test
Reinstall covers and accessories, start the engine, and watch for cam-correlation or injector-related fault codes.
Common Mistakes
- Prying against the head to remove injectors — use the puller from the kit instead
- Reusing injector seals — cheap insurance against a comeback leak or misfire
- Impacting the crank pulley bolt — always counter-hold
- Skipping the two-turn verification — essential on a multi-cam V6/V8
See our full specialty and diagnostic tools lineup for more Mercedes-Benz service essentials.