Shifting issues due to internal problems in high mileage automatic transmissions can be difficult to resolve without transmission replacement.
Resources for the Repair and Maintenance of your 1991 Volkswagen GTI
1991 Volkswagen GTI
1991 Volkswagen GTI Problems
Reverse gear failures and noise in the manual transmission models are common.
Electrical issues that are difficult to diagnose—and sometimes intermittent—are typically due to ground wiring issues. The most troublesome ground locations are under the battery or at the engine.
The water pump and/or other cooling system may develop a coolant leak. Oil leaking from the valve cover gasket is also common.
Heater core leaks are common in this model, more so if the wrong anti-freeze/coolant is used in the cooling system.