500 Injection Pump Timing

Hattrick

Member
Looking to take the Bosch pump off my 500 and need to know how things should be aligned before removing. I have rotated the engine to TDC and rotated multiple times and the needle in the pump alignment windo never lines up. Also there are two marks in the inspection window. One mark on the pump side and one on the engine side. One of the marks has gradiant lines. Seems like the engine should be TDC and the pump alignment needle should line up. It should be timed right as the tractor ran and has not been worked on since then. Any help appreciated.
 
When the drive hub mark aligns with the pointer is what is important, when you look at the head gear if the marked tooth is in the window pump is ready to fire # one, if gear mark is not in the window pump is on #six as drive hub turns engine speed, head gear is 1/2. When the hub mark is at pointer the head gear will be off about one tooth, they do not align together. Head gear mark is used at cam base circle, hub mark is port closing as tappet has started up the cam ramp away from base circle. Most tractor repair manuals have this info wrong, Oliver IT books I have are the only ones I've seen that has it right like the original American Bosch books show.
 
Forgot to add, TDC is not the correct timing for your tractor, most PSB pumps were 25 to 32 BTDC, will look tomorrow and find what hub mark should be if no one else has the spec handy..
 
Thanks Diesel.Sorry for my ignorance as i do not understand the terms. Can you explain what the drive hub and head gear are.
 
Drive hub is at the front of the pump, should be a cover or plug to remove to see the pointer. Head drive gear is under the two bolt cover on the pump side. Do you have a parts and/or service manual, that would help if you don't..
 
Thanks again diesel. That is about where it lines up. I am curious though. If you were to start from scratch not knowing where the motor is at it seems like it would need to be based on TDC. Maybe it is based on the mark on the drive side of the pump as there appears to be marks on both the drive side and the pump side and they are not lined up. I realize the pump was used in many applications but you would have to have a reliable way to line it up if starting from scratch.
 

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