Although a powerful engine for its time, the 16 Valve engine can experience some problems that can be solved easily. One of the few problems is oil pump gear problems leading to broken timing belts. The oil pump gear itself can fail around the mounting flange, or, more often, the weak 8.8 (grade 5) grade bolt holding the gear can break. It is strongly recommended to use a 10.9 (grade 8) grade bolt when replacing the oil pump gear. Another cause for timing belt failure is improperly adjusting the timing belt on engines with a manual tensioner (1989 to very early 1990 models only) or improperly adjusting the balance shaft belt. Because this is an interference engine, damage will occur if the timing belt fails. Another common occurrence is that the balance shaft's oil seals are prone to leak on older engines. New replacement sealings tend to start leaking again due to 'worn in irregularities' on the shaft itself. Many people have removed the balance shaft belt or the balance shaft assemblies altogether to prevent belt failure and/or leakage. The balance shafts are only there to lessen high rpm second order vibrations, and removing them will only affect high rpm vibrations. Once all the common problems are solved, the 16 Valve engines are just as reliable as their SOHC counterparts.