For enthusiasts of German engineering, the W124 Mercedes-Benz platform holds a special place. Renowned for its robust build quality and timeless design, these vehicles offer a fantastic base for customization. My journey started with a 1995 Mercedes E320 wagon, a car that, while showing its age, possessed undeniable potential. Knowing a head gasket issue was looming, I saw an opportunity to not just repair, but significantly enhance this classic estate. The solution? A performance-oriented heart transplant in the form of a C36 AMG engine from the same era.
The idea of slotting a C36 AMG powerplant into the 95 Mercedes E320 was initially sparked by a conversation with my trusted parts supplier. He suggested the swap would be surprisingly straightforward, almost “plug and play.” Serendipitously, a suitable C36 engine became available locally, making the ambitious project a tangible possibility. Instead of simply addressing the E320’s impending head gasket failure, why not elevate its performance with the more potent 3.6-liter AMG engine? The decision was made: the 95 Mercedes E320 wagon was about to receive a significant upgrade.
Opting for the W124 Wiring Harness and Engine Integration
A crucial aspect of this engine swap involved the wiring. The C36 AMG wiring harness that came with the engine was unfortunately unusable, being cut and incomplete. However, this wasn’t a major setback. We cleverly decided to retain the original W124 3.2 wiring harness from the E320. To make this work seamlessly, we transferred the front pulleys and belt-driven air pump from the original 3.2 engine onto the newly acquired 3.6 AMG unit. It’s worth noting that if a pristine C36 wiring harness were available, it would indeed allow for a more direct installation, potentially even utilizing the C36 ECU. However, sourcing a correct and undamaged C36 harness can be challenging and costly, with several versions existing. Sticking with the W124 harness proved to be a practical and effective approach. Furthermore, the existing automatic transmission in the wagon, which had a recent rebuild receipt, was deemed suitable and retained for this stage of the project.
The engine swap itself proceeded relatively smoothly. With the engine bay accessible, it was the perfect time to address preventative maintenance and upgrades. New motor mounts and steering components were installed, ensuring refreshed mechanicals to complement the new engine. Knowing the W124’s susceptibility to rust, I proactively treated common trouble spots like the battery tray and areas beneath the washer and coolant tanks with POR15, a robust rust preventative coating.
Image showing the subframe removed from the 95 Mercedes E320 during suspension work, highlighting the extent of the project.
ECU Tuning and Unleashing the 3.6 AMG Power
Post-swap, the next hurdle was engine management. Initially, the stock 3.2 ECU was used. While the car ran, the performance was noticeably constrained, essentially mirroring the original 3.2 power output. To fully realize the potential of the 3.6 AMG engine in the 95 Mercedes E320, ECU tuning was essential. After an extensive search, Speedtuning USA in Maryland was identified as capable of creating a custom chip to optimize the ECU for the 3.6 specifications. The result was transformative. The bespoke chip unlocked the significant power gains expected from the engine swap, breathing true AMG performance into the wagon.
Currently, the 3.2 crossover pipe remains in place, although the correct 3.6 version is on hand. While debates exist regarding any substantial power difference between the two, the 3.6 crossover pipe undoubtedly adds to the authenticity of the AMG conversion. Plans are underway to install the 3.6 crossover, which necessitates a minor modification to a later-style valve cover to accommodate wiring for the injectors within its internal channel. This installation will coincide with addressing a valve cover gasket replacement and an upgrade to a better wiring harness.
Addressing a Persistent Idling Issue and Suspension Overhaul
An ongoing issue with the 95 Mercedes E320 has been an erratic idle. Despite replacing components like the throttle actuator, cleaning injectors, swapping the MAF sensor, performing a tune-up, and replacing the coolant temperature sensor, the hunting idle persisted. Despite this minor annoyance, the car otherwise runs exceptionally well.
Last year brought a comprehensive suspension overhaul. To enhance handling, 500e sway bars were installed both front and rear, complemented by early Sportline control arms up front. The rear subframe was removed to replace bushings, and while the suspension links were already relatively new, H&R springs and Bilstein Sport shocks were fitted at the front. However, the H&R springs resulted in a slightly more pronounced front drop than desired, even with the tallest available bump pads.
The 1995 Mercedes E320 wagon showcased after the suspension work, initially fitted with Monobloc wheels, highlighting the lowered stance.
Initially, Monobloc wheels with 225/45/17 tires were fitted. However, rubbing issues on the passenger-side inner fender became problematic. Switching to 16″ CLK lightweight wheels with 205/55/16 tires resolved the rubbing and dramatically improved the ride quality. The CLK wheels offered a significant unsprung weight reduction, contributing to the enhanced driving experience. Despite the wheel change, the slight front-end sag remains, and exploring alternative front springs or adjusting rear height via the self-leveling system or smaller spring pads are potential future adjustments. Acquiring a Mercedes spring compressor is also on the wishlist to facilitate easier spring changes.
Exhaust Upgrades and Future Performance Enhancements
A larger downpipe has been acquired and awaits installation. The flanged components, including a high-flow catalytic converter and a test pipe, promise a straightforward installation. Deleting the catalytic converter is known to yield notable power gains, with European-spec 3.2 engines producing approximately 20 horsepower more than their US-market, catalyst-equipped counterparts. A custom flanged resonator delete pipe, designed to connect to the stock rear muffler with its 2.5″ inlet, is also in progress. These exhaust modifications are anticipated to enhance both the sound and performance of the 95 Mercedes E320 in the near future. Furthermore, a second, more aggressively tuned ECU chip from Speedtuning is ready for evaluation, awaiting the exhaust modifications to maximize its benefits.
Interior and Exterior Aesthetics: Subtle AMG Touches
The interior of the 95 Mercedes E320 remains largely original, save for the addition of a 500e 390mm steering wheel, a subtle upgrade appreciated by Mercedes enthusiasts. A rough AMG Generation 1 body kit was generously donated, presenting a future project to refine the car’s exterior. While the side skirts are in good condition, the front and rear bumpers require significant fiberglass repair work, making this a longer-term cosmetic enhancement project.
A detailed shot of the sought-after 3.6 crossover tube, a key component for maximizing the performance of the AMG engine.
The Manual Transmission Conversion: The Ultimate Upgrade
Perhaps the most significant planned upgrade for this 95 Mercedes E320 project is the manual transmission conversion. The original automatic transmission, while functional, feels mismatched to the AMG engine’s power delivery, which peaks in the higher rev range. The automatic’s responsiveness feels sluggish, and an annoying 2nd to 3rd gear flare further highlighted its limitations. While a K2 spring kit could potentially mitigate the flare, the allure of a manual swap was too strong to ignore.
The Mercedes E320 wagon fitted with CLK lightweight wheels prior to the suspension overhaul, showcasing the wheel style.
Fortuitously, an untouched 5-speed manual transmission from an 86 300e was located at a local salvage yard. Crucially, this provided all the necessary components for the conversion, including the pedal box and a shorter driveshaft. An advantageous trade with a friend secured a Getrag close-ratio 5-speed “dogleg” transmission, renowned for its performance orientation. Joining a group buy for a lightweight single-mass flywheel proved ideal, as it allows for bolting up the stock automatic transmission ring gear. This ring gear is essential for proper engine idling and computer compatibility in later 24-valve Mercedes models. A custom clutch and pressure plate setup is anticipated to arrive soon, completing the core components for the manual swap.
Image showcasing the new downpipe components intended for installation, part of the exhaust system upgrade.
The plan is to remove the drivetrain once more to facilitate several tasks concurrently. These include addressing the wiring harness and valve cover, installing the 3.6 crossover tube, investigating the EGR system as a potential cause of the idle issue (easily accessible with the engine out), and replacing the oil pan gasket. With potential access to shop space through a friend, this major phase of the 95 Mercedes E320 transformation, encompassing the engine and transmission swap, is projected to occur within the next couple of months.
Image of the custom lightweight flywheel designed for the manual transmission swap in the 95 Mercedes E320 project.
Another view of the custom flywheel, highlighting its design features and compatibility with the Mercedes engine.
Conclusion: A 95 Mercedes E320 Reborn
This 1995 Mercedes E320 wagon project is an ongoing testament to the enduring appeal of the W124 platform and the rewarding nature of automotive customization. From the initial engine swap to the planned manual transmission conversion and beyond, the aim is to create a unique and enhanced classic Mercedes, blending robust vintage charm with carefully selected performance upgrades. The journey has been filled with learning experiences and the satisfaction of breathing new life into a timeless machine.
