Substitute 8N Hydraulic Pump For TO-30 Pump

Is the Ford 8N hydraulic pump a possible relacement for the pump in my TO-30?  July 3, 2016.

Many parts are interchangeable between the two pumps but the entire pump assembly is not. The scotch yoke pistons, bearing blocks, valve chamber parts are interchangeable. There is a difference in the valve chambers themselves in that the TO-30’s use O-rings to seal the chambers to the main casting, and the 8N uses gaskets like the earlier 9N, 2N, TE/TO-20 units.   Those side chamber assemblies can be used on the TO-30 if gaskets are substituted for the O-rings.

The control valve assemblies are completely different, and unique to the TO-30 pump. If the casting on your pump is still serviceable, you can purchase an after-market kit to rebuild your pump that will include gaskets, pistons, bearing blocks, etc. You may need to purchase a relief valve specific to the TO-30. Depending on the rebuild kit you purchase, it may include a control valve. However, the TO-30 control valve includes an oscillator, which is a rod with a square end attached to the end of the valve, and an eccentric on the crankshaft. Many of the replacement valves have a pair of milled slots in the end which allows the oscillator assembly, salvaged from the old valve, to be attached to the new replacement valve.

If your casting is cracked, you will have to purchase either a used casting, or a complete used pump. I would suggest rebuilding any pump you purchase though you may be able to find a serviceable one that you can use as is. At a minimum I would recommend changing the relief valve, and the rings in the lift piston. Another option is to replace the lift piston with a Ford NAA style lift piston;  it has an O-ring with backup ring seal.

A complete rebuild would include making sure the draft control spring plunger, and clevis are free so complete and proper adjustments can be made once the pump is reinstalled.