Engine Replacement Ideas

John Clark · 01-01-2001, 05:27 PM

Suggestions on engine replacement A quick check of the internet shows a Cummins 555 for $4500 and a Cummins 903 for $3500. I think a 903 gives about 350 hp vs. your 555 at 240. They look damn near identical, and Newell used both engines in their late 70s early 80s coaches. Maybe an "old timer" at Newell can clarify the differences.

Neweller · 08-26-2004, 04:24 AM

The VT-903 in my opinion is a much better engine than its little sister the triple nickel (555). Both were used in the marine industry and the 903 had been heavily used by the military in the Bradley's and in AG tractors like a Stiener, and even some dump trucks like the LNT9000. The 903 with turbo can be tuned up to 410hp which is much better than the 555.

Ken

farmell · 10-22-2007, 02:39 AM

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

Neweller · 10-23-2007, 03:34 AM

I helped a friend put a 5.9 Cummins that his son built into a MCI Bus conversion in replacement of a DD and the mounting was the most critical aspect of it. Other than that it went pretty slick. He ended up some serious horsepower and torque out of the deal and loves the bus. I told him to buy a Newell and convert one over. The reason I brought this up is that my second Newell I picked up with a 555 and the previous owner filled the tank with gasoline and started to drive it and screwed up a low mileage coach. I picked it up as/is and it got a new triple nickel which turned out to be a nightmare on expense do to a ripoff mechanic down in California.

Ken