How to Change the Timing Chain on a 1989 Mercedes 420

1. Purchase a timing chain made specifically for a 1989 Mercedes 420 from an auto parts store or online.
2. Lift up the vehicle hood. Disconnect the negative battery cable. Drain oil from the engine and coolant from the cooling system to maintain a clean working environment. Use drip pans to catch oil and coolant. Disconnect spark plug wires and remove spark plugs.
3. Locate and remove the front cover, cylinder cover and chain tensioner. Refer to the vehicle owner's or service manual to properly locate and identify these parts.
4. Rotate the engine to position the No. 1 cylinder at Top Dead Center (TDC) of the compression stroke.
5. Align the mark on camshaft to the mark found on the front camshaft journal to remove the timing chain.
6. Attach the new timing chain by aligning the marks on the timing chain with the marks found on the crankshaft to ensure proper installation.
7. Reattach the chain tensioner, cylinder cover and front cover. Reconnect the negative battery cable. Add new oil and coolant. Start the engine to determine if the timing chain is installed properly.