Toyota Prius: Part 4
TOYOTA PRIUS | The Fourth Report
Oil Leak from the Damper?
A long-term report on our second long-term test car, the Toyota Prius, is finally here. A rare issue was discovered during its recent routine inspection, requiring a visit to the pit.
Text by OPENERSPhotos by Katsu Suzuki
Unnoticeable While Driving
During a routine inspection at Tokyo Toyota Motor Edogawa branch, where we regularly service the car, a highly unusual problem was reported: an oil leak from the front right suspension damper. I hadn't noticed anything while driving, and it seemed odd for such an issue to arise after only about 23,000 km since its introduction as a long-term test car. So, we decided to witness the repair process firsthand.
We were promptly shown the damper replacement procedure in the pit. After removing the tire, we were shown the damper's condition. Even with a flashlight, it was difficult to pinpoint the source of the oil leak. It was only upon touching the damper that we could feel the oil residue.
Even Staff Refer to Manuals
The process then moved to actually removing the damper. With Toyota's extensive range of models, even experienced technicians must refer to the manual and follow each step meticulously to avoid errors. We were shown the printed manual, which comprised 24 A4 pages detailing the work process. For the Prius, removing the suspension mounting nuts required dismantling not only sensors but also the cowl top panel, wipers, and wiper motor. This part of the process was the most time-consuming.
A Seep, Not a Leak
After approximately 20 minutes of work, the damper was removed. Upon inspection, we confirmed a slight "seep" of oil. According to Mr. Kazuhiko Kojima from the Edogawa branch, this repair was covered under the manufacturer's 5-year/100,000 km warranty. However, he noted that the amount of oil leakage was less than what the manufacturer typically recommends for replacement, suggesting that the dealership might bear some of the cost. Nevertheless, the meticulous service of Toyota-affiliated dealers, prioritizing safety by replacing parts even for minor issues, was truly impressive.
A Refreshed Suspension in Just Over Three Hours
The replaced parts were reinstalled, and the Prius, our second long-term test car, was connected to a diagnostic tester and then driven by a technician. No issues other than the damper were found, and the entire process was completed in about three hours. Although the oil leak hadn't affected daily driving, the car with the refreshed dampers felt noticeably more responsive and stable.
Interestingly, this oil leak from the damper is reportedly unprecedented for the third-generation Prius, making it an exceptionally rare case. As it uses a conventional damper design, the issue is likely attributed to a random occurrence rather than a structural defect. Despite the car having been used for track driving, we plan to continue reporting on any further observations during its regular use.