1991 Mercedes-Benz 350SD

Introduction

The 1991 Mercedes-Benz 350SD is a luxury sedan powered by a naturally aspirated 3.5L inline-6 turbo-diesel engine paired with a 4-speed automatic transmission. The engine produces 155 horsepower and 258 lb-ft of torque. It was appreciated for its smooth ride, refined interior, and impressive fuel economy. However, it was also criticized for its lack of power, expensive maintenance costs, and some reliability issues.

Engine

• 3.5L Inline-6 Turbo-Diesel

  • Turbocharger Failure: The turbocharger may develop leaks or fail completely, leading to reduced power and poor fuel economy. Symptoms include black smoke from the exhaust, reduced boost pressure, and a rattling noise. Requires replacement of the turbocharger. $1200 - $2000+
  • Head Gasket Failure: The head gasket may fail, causing coolant and oil to leak and mix. Symptoms include overheating, white smoke from the exhaust, and low coolant levels. Requires removal of the cylinder head and replacement of the head gasket. $1500 - $3000+

Transmission

• 4-Speed Automatic

  • Transmission Fluid Leak: The transmission may develop leaks, causing fluid loss and transmission slipping. Symptoms include difficulty shifting, delayed engagement, and a burning smell. Requires replacement of seals or gaskets. $300 - $900+
  • Torque Converter Failure: The torque converter may fail, causing shuddering, slipping, or difficulty shifting. Requires replacement of the torque converter. $1000 - $2000+

Suspension

• Rear Self-Leveling Suspension Failure: The rear self-leveling suspension may malfunction, leading to uneven ride height and reduced handling. Symptoms include a sagging rear end and difficulty leveling after loading. Requires repair or replacement of the suspension components. $600 - $1500+

Electrical

• Alternator Failure: The alternator may fail, leading to electrical system malfunctions and battery discharge. Symptoms include dim or flickering lights, difficulty starting, and a battery warning light. Requires replacement of the alternator. $500 - $1000+
• Window Regulator Failure: The window regulators may fail, causing windows to become stuck or inoperable. Symptoms include difficulty raising or lowering windows and a grinding noise. Requires replacement of the window regulator motors or switches. $200 - $500+

Exterior

• Rust on Undercarriage: The undercarriage of the vehicle may develop rust due to exposure to moisture and salt. Symptoms include visible rust, weakened frame members, and potential safety hazards. Requires professional rust removal and prevention measures. $500 - $2000+

Interior

• Climate Control Malfunction: The climate control system may fail, leading to inadequate heating or cooling. Symptoms include uneven temperatures, blower fan issues, and refrigerant leaks. Requires diagnosis and repair of the system. $300 - $900+
• Dashboard Pixelation: The digital dashboard display may develop pixelation or fading, making it difficult to read gauges and information. Requires replacement of the dashboard cluster. $500 - $1200+

Summary

While the 1991 Mercedes-Benz 350SD has its strengths, it is not without its issues. The engine and transmission can experience some costly failures, while the suspension, electrical system, and interior components also have their own set of problems. Rust on the undercarriage is a potential safety hazard that should be addressed. Overall, the reliability and repair costs of the 350SD can be a concern for potential owners.