920 loader injector o rings

i have 2 injectors leaking antifreeze. What does it entail changing them out?

Its a 1975 3304 engine its leakinf antifreeze from under the injectors I dont have a manual

It must have a 3304 PC engine.The DI engines wouldn"t do this. There are seals on the pre cups. If I remember right they are screwed into the head with two seals on them.You may need a special tool to get them out. It"s been 20 years since I worked on a 3300 series engine. Take the machine serial number and arrangement number to your CAT dealer and they will tell you what parts you will need.

It is best to change all four precombustion chamber seals and gaskets (washers) as the others are liable to leak too,you need a special tool to remove the prechambers (Cat 5F8353 Wrench),clean off the area of dirt/dust etc,drain the coolant,disconnect the glow plugs,(if they are going to be in the way remove them) remove the four injector pipes,remove the four injector valve retaining nuts,lift out the injector valves,if they are tight attach one of the pipes and use a heel bar under the nut to prise them loose,with the valves out insert the special splined key and undo the chamber,number each chamber to its cylinder,remove the top o'ring and bottom washer,lable the washer,remove the others and do the same,the washers comes in different thickness,take the four to the dealer and get a new one to match each one,put the new ones on the respective chambers,that saves a lot of trouble getting the glow plugs in the right place,put anti seize on the chamber threads and liquid soap on the o'ring,install the chambers and tighten them to 150 Lb FT +/- 10Lb,make sure the injector valve and adapter are clean,the valve and adapter are just finger tight,put them in place and fit the nuts with new o'rings tighten them to 105 Lb Ft +/- 5Lb,put the new dust seal over the pipe adapter and put the pipes back on,connect the glow plugs,fill with coolant job done,if the glow plugs had to be removed put anti seize on the threads and tighten them to 8 Lb Ft
Good luck
AJ

Aj. Thank you so much for your indepth reply.

There are splined wrench's on ebay right now,you can't do the job without one,have a look at the listing at the link below.
AJ
http://www.ebay.com/itm/New-Tool-5F8353-Precombustion-Chamber-Wrench-for-Caterpillar-/370793202995

AJ. thank you for the ebay link for the tool. was able to purchase. ⛄️