Developing the "multifuel" into a tractor engine

[JasonS]

I found a paper authored by White Motor Corp which outlined what was done to convert the multifuel engine into a suitable tractor engine (D4800 and D4800T). You may find this interesting.

1. The military engine was a set of compromises but the basic engine was successful
2. Hercules, after building the multifuel for five years was aware of the weaknesses inherent in the engine and able to correct the deficiencies in a period of one year
3. Here are the improvements/ corrections
   1. Compression ratio was reduced from 22:1 to 18:1 to reduce firing pressure and noise while still having "excellent" cold start ability
   2. The connecting rod was "not adequate" in the multifuel engine. The I-beam section was stiffened nd the pin diameter was enlarged. Note that, based on the engine manuals, the D4800, D4800T, and D5000 actually have the same pin diameter as the multifuel. Often when overhauling the tractors, they will use the multifuel piston to improve cold starting.
   3. The liner was changed to a press-fit and piston fit (camming) and ring combination improved. This improved piston operating temperature and oil control. Replacement tractor sleeves are offered with a standard or 0.005 oversize fit.
   4. Bearing clearances were reduced for better oil pressure at elevated operating conditions.
   5. The oil filter base was modified to prevent oil drainback at shutdown. This was done specifically to have oil pressure at the turbo at startup. Not sure if this is a miscommunication as the tractors have the anti-drainback valve in the externally mounted oil pressure regulator.
   6. Higher output water pump design which also reduced parasitic horsepower draw. This is a larger diameter pump with curved blades. I don't see how this would ever fit the deuce. https://www.antiquetractorsrus.com/a-403835058pumpwater.aspx
   7. Cylinder head modified to improve water flow between the valves and reduced thermal distortion of the valve seats.
   8. PSJ injection pump. Later tractors used the Roosa pump. This requires a different geartrain and injector lines from the tractor.
   9. The rated engine speed of the D5000 is 2200 rpm. The no load speed is 2370-2420.

 

[Elk1111]

Could the tractor engines be modified slightly to fit in an M35 series truck or are the differences to great?

 

[yolner]

Well one thing that should swap over is the improved water pump. Looks like they're around $300 and still available.

 

[patracy]

I know Oliver used the same (or very similar) engine in a few tractors. I think White did as well

 

[Elk1111]

I guess my main question would be if it would be a direct bolt in after swapping the bell housing? The rest of it should be pretty straight forward as far as moving the intake, exhaust etc. It seems like they were built to be a lot more reliable and if I need a new engine for this M52 I’m working on it just makes more sense to go with something that’s going to last longer than the traditional multifuel and not have to do all the modifications to put in a Cummins or a DT of some sort.

 

[fleetmech]

Im not overly familiar with the tractor variant, but wasnt the power turned way down from the army rating? I can imagine that de-rating down to a big (for the time) tractor 80-100 hp would drastically reduce pressures and increase lifespan, though that wouldn't fly in our trucks...

I wonder if that 'psj' pump is simpler/ cheaper/ has more parts available?

 

[yolner]

I did some googling and that injection pump seems to be even harder to find parts for than our multifuel pump.

 

[Charlie175]

Seen some pulling pictures where they had stacks of engines outside of the shop. One would blow and they would just drop in another one. I guess surplus engines were cheap.