Re: Trim pump Manufacturer
Prestolite quit making hydraulics in the early 1990's. They were bought out by another company and quit making small DC motors later in the same decade. The aftermarket motors are being made by a wide variety of campanies. Arco seems to be the best overall quality. API has problems with end play tolerance and the end of armature likes to round off. The Chinese motors have plastic circuit boards that often warp it the motor gets too hot. All the valve bodies I have seen go back to a single factory in Taiwan. It looks like the 1990-1992 Prestolite but the aluminum is softer than original and the internal threads are slightly different. The original 1991 design by Prestolite had problems with trim push-back pressure on 120-150HP. Over time it would stretch the aluminum and burst open the check valves. IMO, if you can swap check valves from a 35HP during rebuild then an original PT valve body will outlast the chinese product. But, realistically, even with soft aluminum it will take a number of years to stretch out a check valve and having new port threads is often an over-riding concern.
Hope that helped.
