The naturally aspirated M156 and M159 AMG V8s — found in the C63, E63, CLS63, ML63, and CLK63 — are chain-driven, four-camshaft engines, and a timing job here means keeping two banks of camshafts correctly referenced at once. It's a more involved job than any inline-four on our site, and the locking plate this kit centers around exists specifically to keep all four cams honest while you're working.
Tool You'll Need
- Engine Timing Tool Kit — camshaft locking plate and alignment bar sized for the M156/M159 AMG V8
You'll also need a crankshaft holding tool, a torque wrench, and the correct chain, guide, and tensioner kit for your specific engine — as always, replace the full wear set together rather than the chain alone.
Why Four Cams Changes the Approach
With two banks each running an intake and exhaust cam, there's twice the opportunity for something to drift out of reference while you're focused on one side. The locking plate in this kit is designed to hold all four camshafts in their correct relative position simultaneously, rather than trying to hold each one individually and hoping nothing shifts while your attention is on the other bank.
Step 1: Establish TDC on Cylinder 1
Rotate the crankshaft, counter-held rather than impacted, to Top Dead Center on cylinder 1.
Step 2: Fit the Locking Plate
Install the locking plate across all four camshafts, confirming it seats flush against every reference point before moving on. If it's binding anywhere, stop and recheck crank position rather than forcing it.
Step 3: Access the Chain and Tensioner
Remove covers and accessories per your engine's specific procedure to reach the timing chain and tensioner assembly on the bank you're servicing.
Step 4: Remove the Old Chain Components
Using a proper ratcheting tensioner tool, relieve tension carefully, then remove the old chain, guides, and tensioner as a complete set.
Step 5: Install New Components
Fit new guides, a new tensioner in its retracted position, and route the new chain per the factory diagram, with the locking plate still in place across all four cams the entire time.
Step 6: Release and Verify
Release the tensioner, remove the locking plate, and rotate the crankshaft through two full turns by hand, bringing it back to TDC. Reinstall the locking plate and confirm every camshaft still references correctly — on a four-cam V8, this check matters even more than on a four-cylinder engine.
Step 7: Reassemble and Verify Startup
Reinstall covers and accessories, start the engine, and confirm no cam-correlation faults appear.
Common Mistakes
- Locking only one bank and assuming the other holds — the locking plate is designed to reference all four cams together for a reason
- Impacting the crank pulley bolt — always counter-hold
- Replacing only the worn chain — guides and tensioners are wear items too
- Skipping the two-turn double-check — the more locking points involved, the more this step matters
See our full specialty and diagnostic tools lineup for more AMG-specific service essentials.