This is an old thread. I have picked up a little here and a little there over the elapsed time since this thread originated.

Some of my thoughts have changed to some degree. What I missed back then and may be of signifigant importance is the high pressure spikes released by the element barrels when loading and the elements pistons coming back down to reload. . It is going to be harder to load uniformaly with little to no fuel pressure assisting the new fuel into the elements. If the supply curve is seriously off the condition will be still even worse.

The only way to really know your current status is to install a fuel pressure gauge or at least check it with a gauge. I am even more certain that it is low base fuel pressure that is the principal culprit in the number one rod bearing issues then I was back then.

It simply just wears them out faster as they are saddled with a greater percentage of the work load. The power balance of the engine is disturbed with low fuel pressure to the base.

A requirement that flies in the face of fuel pressure being of no signifigance. The person calibrating the injection pump must make sure the relief valve is in the right area for pressure relief. If it is overflowing in that condition the lift pump is putting out adaquate pressure and volume.

Under those conditions the injection pump can be properly calibrated. To calibrate the injection pump without those requirements being met the calibration is then wrong. Or the pump is then being calibrated to standards that are not what the injection pump manufacturer wanted done.

So when you operate the injection pump at lower than calibrated pressure the calibration will be different than what it was set at. Also if one element is underloaded compared to another further away in the sequence it in effect is also unloading at the injector later that the designers of the injection pump intended.

That is effectively retarding the timing of the injector fed by it. When operating below the overflow recommmended pressure of the relief valve with partially obstructed fuel filters or a weak lift pump for example. The high pressure spikes from the fueling elements are not moderated by the cigar hose as much. Further disrupting things to some extent.

Plus the constant fuel pressure in the injection pump enabled by the relief overflow valve is replaced with a higher pressure initially falling off during the period of the overall lift pump cycle.

It just in general is not either a good ideal or good practice to be running with low fuel pressure in the base of the injection pump. There is no doubt the engine will run though. The manufacturer really wants to see about fourteen pounds and nineteen pounds seems to be better at idle.

All the last posters experience really proved is that he may have inadaquate base fuel pressure in his injection pump.Or it may be good. The only way to really know is to get a meter reading on it.

In many cases it will mean spending less than twenty dollars now or replacing the engine later. Many go the engine replacing route. It takes quite a long time to wear the bearing down. You just in all too many cases are unaware of how much wear has already accumulated before you got the car because of low fuel pressure if it exists. These engines are so noisy one can easily miss the early light knocking of excessive bearing clearance. If wear is present you do not eliminate it with correct fuel pressure. You do take the excess load that that number the number one cylinder has been subject away though. So the future wear should be at a much reduced rate.

If youi buy a 240d with a 616 engine. Finding the fuel pressure very low. I would pull the lower oil pan and plastigauge the number one rod bearing as a preventative measure. You do not know how long that engine was used with low fuel pressure. Long enough and you may find the bearing has excess clearance and should be changed.