1991 Mercedes 420SEL Timing Chain Repair

[ron59b]

Good evening, all

I need help with a 1991 Mercedes 420 SEL in strong overall shape. I looked at the car today. The owner shared photos and details. I want advice before I move forward.
Here is the situation.

• Exterior and interior look excellent.
• The timing chain snapped, and the chain hit the front case.
• The housing for the chain case shows a crack.
• I need to know if a new chain and new guides will bring the engine back.
• I also need to know if the chain failure pushed the valves into the pistons or if the engine stayed safe.
• The sunroof motor needs service.
• The exhaust system is original. It needs an update soon.

Details from the owner.

• 1991 Mercedes-Benz 420 SEL
• 4.2 V8
• 171,000 miles
• Second owner
• Strong care history
I want guidance on next steps.
I would like to know what to look at first and what a full repair list should include.

Anyone with experience on the M116 engine, please let me know your thoughts.

I followed up and checked the engine specs. The M116 4.2 V8 in the 1991 420 SEL is a non-interference engine. This gives me some hope that the valves stayed safe when the chain broke. I still plan to inspect the guides, sprockets, tensioner, and the cracked timing cover once the front of the engine is open.

I welcome advice from anyone who has rebuilt this timing assembly or dealt with a broken chain on this engine.

Thank you for your time,

Ron