[farmell]

I used to run them in a Massey 4880 & 4900. They're not junk but there are a number of things to keep them running well. First, and most important, keep a good handle on your coolant. 903's are famous for liner cavitation. Check the coolant with test strips and make sure you keep the additive package up to snuff or the coolant filter, whichever you prefer, as they do the same thing. Of coarse keep the oil & filter changed often too. Also, I would run the overhead on them every 700 hours or so, just to make sure the valves and injectors are set right too. I took my 4900 from a stock 375 hp up to 600 with no problem. I took the pump off and we just changed one of the washers and springs in the pump. Be careful as this is a PT pump and runs the same as the 855, but it rotates the opposite way, so they won't interchange. Also, This pump is really not an injection pump, in that it does not meter and pressurize the fuel to a high pressure. It functions somewhat like a lift pump, and basically feeds fuel to the injectors. Since the injectors are driven off the engine camshaft, they are what time, meter, and pressurize the fuel for combustion. To have a pump shop go through the PT pump is only about $300, it's the injectors that are pricey. I know a guy with a 4880 Massey that was up near 1000 hp with the factory injectors, just cranked the snot out of the PT pump. Took a couple of hours to do and just switched out washers and springs. Also, 903's won't lug down very far. Keep the revs up around 2700 and you'll be ok. Below about 1900 they are a dog and don't have much torgue You can still find parts for them pretty cheap. Most guys hated them in trucks, but they weren't too bad in farm tractors. The military still uses them in some tracked vehicles at 800+ hp, so they must not be too bad. they just don't lug down like an 855. you just have to get use how I've got a complete Cummins shop manual for the 903 series engine that I would probably sell. It's a great resource for anything to do with these engines.

Mike