The 617 is not as failure prone because there are more power strokes in my opinion. Yet if a rod is destroyed it will almost always be the number one even on the 617. Look for the relief valve spring thread started by carven I believe.

The gentleman posting is showing compression numbers that may indicate more wear has occured in the number one cylinder. This could be consistant with the cylinder working harder than the others. Still all this is just subjective and came about when a poster a long time ago asked on site. Why does the rod failure almost seem to be the number one on the 616?

I could never buy the length of the oil feed to the number one rod bearing as the cause. The distance is shorter than the 617s oil feed for starters. The most likely cause of low base fuel injection pump pressure is running until a fuel filter totally obstructs. The time the filter is so restrictive that it has lowered the operating pressure may be a long time before the filter chokes right up.

So without a pressure gauge in the circuit you should change the fuel filters pretty often. The gauge setup just saves money by telling you when you should. Also if pressure is low you have lost the cooling effect of the fuel oil carrying the excess heat back through the return lowering the injection pumps lifespan perhaps. There is no flow through the return relief valve at substandard pressure. That is unless the spring in the relief valve or the sealing of the valve seat in there is defective.