What Actually Makes This Car Tick
The 2014-2017 C217 generation AMG S63 Coupe uses the M157 biturbo 5.5L V8, not the hand-built M177 found in later models. That distinction matters because the M157 has a fundamentally different oiling system and timing chain design that causes specific failures BMW owners don't see and typical Mercedes techs miss entirely. People call it Berlin's bestseller because it became the default choice for taxi operators and high-mileage fleet buyers who wanted something that looked like a $180,000 car but could actually survive 200,000 kilometers. The S63 Coupe sells used for roughly half its original price, which makes parts costs look cheap until something actually breaks. The first thing you need to understand is the M157's position of the oil pump. It sits at the front of the engine behind the timing chain, meaning any timing chain service requires removing the front cover, all the chains, the water pump, and most of the accessory brackets. BMW's N63 does something similar, but Mercedes compounded it by routing the oil filter housing through the front cover assembly. A standard oil change takes forty minutes. A timing chain replacement takes a full weekend for a competent mechanic who isn't fighting seized bolts on a high-mileage engine.
The Oil System You Need to Know About
The M157 uses a dry sump architecture with a separate scavenge pump. This sounds fancy but it's actually where most expensive problems start. The scavenge pumps have their own timing chains that stretch, and the pickup tubes in the oil pan can crack from heat cycling if you skip oil changes regularly. I ran into this on a customer car last year. 92,000 miles, previous owner had skipped services for about three years. The car was throwing P00AF and P00B codes for camshaft timing at low load. Most shops immediately recommended a cam phaser replacement. The actual problem was the scavenge pump chain had stretched enough that oil pressure to the phasers dropped below threshold during light throttle operations. Replaced the scavenge pump chain kit, cleared the codes, and the car ran fine. The phasers were fine. That job would have cost someone four thousand dollars in parts and labor for nothing.
Common Failure Points
The timing chain guides on the M157 are plastic, specifically reinforced nylon, and they degrade with heat. Around 80,000 to 110,000 miles you'll start hearing the characteristic rattle on cold startup that gets quieter as oil pressure builds. This is the primary chain set, not the secondary scavenge pumps. Replacement involves dropping the subframe on some configurations and dealing with the HVAC housing removal on others depending on whether you have the 7G-Tronic or the older 722.9 transmission. Secondary chain stretch affects the scavenge pumps and the oil pump itself. When these stretch, you get low oil pressure warnings at idle and the cam timing correlation codes I mentioned. The fix is the entire front chain kit including all three pump drives, new guides, and tensioners. Doing just one section rarely solves the problem long-term because the chains wear together. The cam phasers themselves are durable but not indestructible. The internal gears can strip, particularly on engines that have been subjected to aggressive tuning without proper supporting modifications. A stock S63 Coupe making around 577 horsepower is generally reliable if maintained. Push it to 700 wheel horsepower on pump gas and you're spending money on phaser replacements within 30,000 miles.
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Transmission Considerations
The 7G-Tronic Plus (722.9.15) that came mated to the M157 is actually robust, but it has a known weakness in the input shaft seal area. Around 70,000 to 90,000 miles the seal hardens and leaks, often mimicking a much more serious internal transmission failure. The fluid level will drop, the transmission will enter limp mode, and if you don't catch it early the valve body gets starved and starts burning through clutches. The fix is straightforward: replace the seal, clean the pan, and refresh the fluid using the correct Mercedes spec 236.15 fluid. Don't use universal ATF. The friction characteristics matter for the adaptive shift strategy and this transmission learns your driving style aggressively. Wrong fluid makes it shift harshly and triggers code P084E for pressure control issues.
Tuning and What Actually Works
The M157 responds well to software-only tunes from reputable companies like Manhart, BRABUS, or even the factory AMG performance packages. Realistic gains are 60 to 100 horsepower and 80 to 120 pound-feet of torque with proper calibration. The stock internals handle about 700 horsepower on the crank before you need forged pistons and upgraded rods, so most street tunes stay well within limits. Hardcharging tunes above 750 horsepower require at minimum upgraded fuel injectors and a high-flow fuel pump. The stock fuel system delivers approximately 700 horsepower worth of flow under normal conditions, and the injectors are the limiting factor when you add boost. People who skip the fuel system upgrade and just tune the ECU usually discover this the hard way when they get boost spike-induced lean conditions at wide open throttle.
Brakes and Wear Items
The S63 Coupe came with AMG ceramic composite brakes as an option. They're fantastic when they work, terrible when they don't. The rotors can crack from thermal shock if you drive the car hard and then sit in traffic, and replacement rotors run about two thousand dollars each. Standard AMG brakes are more reasonable at roughly six hundred dollars per axle for pads and rotors, and they'll stop the car adequately if you're not chasing lap times. Every four years the brake fluid needs replacing regardless of mileage. The system absorbs moisture aggressively and corrosion in the caliper pistons is common on older cars. Budget two hundred dollars for the fluid service plus bleeding time if a shop does it. DIY is possible but the ABS module requires proper scan tool activation for the bleeder screws.
Practical Ownership Advice
If you're buying one of these, verify the timing chain service history first. An engine with unknown chain history at 90,000 miles is a gamble that could cost you six to eight thousand dollars in repairs. Ask for receipts. If there are none, assume the chains are original and budget accordingly. Check the oil consumption. These engines are generally tight, but worn valve stem seals can cause blue smoke on deceleration without affecting performance noticeably. A compressor borescope inspection through the glow plug ports will tell you the condition of the rings and cylinder walls in about fifteen minutes. Worth doing before you hand over money. The air suspension on models equipped with it typically lasts 60,000 to 90,000 miles before a bag develops a slow leak. Replacement struts run between four hundred and eight hundred dollars each depending on brand. Many owners convert to coil springs for permanent installation, which actually improves handling and removes a major failure point. It's a common modification and the kits are well-engineered.
Overall these cars are solid platforms with specific known issues that are manageable if you know what to look for. The ones that fail catastrophically are usually the ones where maintenance was ignored or someone tried to extract more power than the supporting hardware could handle. Keep up with the oil changes, address the chain noise promptly, and this behemoth will remain one of the more capable grand tourers you can buy used without financing it into bankruptcy.
