656D Injector or valve?

I recently installed a rebuilt injection pump on my 656D. The
timing is set at 3 degrees per the manual. The tractor starts and
idles as it should with no issues. When I advance to about 1/2
throttle I start to get white smoke (unburnt fuel) from one
cylinder. I did not have this issue with the old pump. Is the new
pump to much pressure for the old injectors? Should one also
install new injectors with a new pump? I also considered that
bad valve could cause this but did not have this issue with the
old pump.

Thanks in advance.

APF
 
I would say the automatic load advance is not adjusted properly. You need to put a window on the timing cover and watch that timing mark when engine is running. The mark should move down two marks at all running speeds with no load. It is designed to retard one mark under half load and retard two marks back to starting point under full load thus the name load advance. Really it needs to be on a dynamometer to make the adjustments correctly but I have adjusted many without dyno. Just rap the throttle from low speed to wide open and the advance should rock back about one mark. Late timing will often sound like one cyl is miss firing. Have had a lot of customers pull a set of injection nozzles and bring them in for repair when this happens. Then I go out and set the advance. I have also set some without even having a window but then I know how they should sound when working correctly. Many repaired or rebuild pumps are not set correctly. One reason is they use calibrating oil and not diesel fuel so viscosity may be different. If this happens to be a hydrostatic drive or very very early 656 this information does not apply completely as they use a speed advance pump. Still needs adjustments but different procedure.
 
The guy that overhauled the pump is about 70 yrs old and has repaired injection pumps for IH tractors his entire life. The tractor is an early gear drive tractor. Also the elevation here is 4000 feet.
 
He's a little young then, just kidding, I'm 78 and repaired quite a few over the years also. Just trying to give you a few hints. An injection nozzle will blow more smoke at low idle if bad than at high idle and on that engine will knock like a loose rod.
 
Pete 23 – I have a 656 Hydro - 282 and I am not happy with the way it is running. It runs OK until it is “wide open”. Then it seems to miss. Also getting a little black smoke at that point. When the load hits it, it sounds OK. You said the hydro has a different system. How is it different?

Where do you live? Do you still work on these injection systems? It would be nice to have someone work on it who really knows and understands the engine.
 
The 282 in the 656 Hydrostatic drive uses a speed advance system. The very early gear drive 656 also used that speed advance. We only sold one 656 gear drive that had speed advance. I believe there may be a few mixed in with speed advance before all gear drive 656 were load advance. The difference is that a speed advance pump has no automatic advance at low speeds and gradually starts to advance the injection timing as the engine speed increases. It maintains that advance at all loads unless speed of engine decreases sufficiently to reduce advance. The load advance works differently and to me gives a smoother running engine under load but may rattle more under no load. The load advance gives full advance as soon as the engine is running. It maintains that full advance at low and high speeds under no load. As you come under a load it retards injection. Now, the reason they used the load advance, which by the way is what all 4 & 560's had, is that in a Roosa master pump, the end of injection is constant except for the advance. The beginning of injection takes place earlier as you come under load due to the governor opening the metering valve, giving engine more fuel. The more fuel it gets the farther out the pumping plungers are forced. That causes them to contact the cam ring earlier so it starts injecting fuel earlier in the cycle. Why IH chose to tell us this was not good, and turn around and use the speed advance is for the engineers to answer. Apparently, due to the increased rpm's the hydro runs they felt the load advance did not meet their requirements. The speed advance is normally not nearly as touchy and need as frequent adjustments as the load advance but it can cause the same symptoms if it does not advance enough. That is usually a miss at higher speeds and works fine under load. Both advances are operated by fuel pressure so if you have low fuel pressure it will not adjust up correctly. You have to put a window on pump to watch advance or have a pointer device which I guess is easier to read, never had one. Of course static timing is just as important and if automatic advance is working correctly you can play with that a little, not much though. Also, a timing light for a diesel does not work on a Roosa master system due to the constant end of injection.
I live out here in western Minn and don't do much tractor work any more. . Too old.
 
Pete 23 -- Thanks for the information. Now I have to find someone who is able to make it run right without costing an arm and a leg. What would cause low fuel pressure? It seems as if this a greater problem in the winter and I am running summer diesel fuel. Could that be a factor? I use it on an eight foot snow blower and the problem is most noticeable then.

BTW -- You and I am the same age -- 78, so I understand the "Too Old" comment. Thanks again.

Ken
 

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