Injection pump ?
 

Recently, I have noticed a vibration that has taken a turn for the worse. This problem would be very random a couple of months ago but is constant now.

The problem is definitely rpm related. I notice it at about 1700-1900 rpm. Below and above that rate it smooths out. Also, I am hearing very severe nailing, and smoke, at lower rpms especially at cold idle. At higher rpms, such as highway speeds, it is not as bad but I do seem to notice a "missing" especially with the car loaded with passengers.There is no increase in oil consumption or blow by.

I am picking up a mechanics stethescope to try and do a little more pinpointing. I tried a large screwdriver but with its decreased sensitivity, I am unsure what "normal" sounds are.

From scratching my head and reading about this, I am thinking it may be the IP. I am suspectiing maybe governor flyweights or something in that area. How difficult is it to access that part of the IP? Any other thoughts as to what I should check?

I would think that it's more likely an injector than the pump. You could find which cylinder it is (either by listening or cracking the lines open) and pull that injector..... maybe swap it with one that works and see if the problem moves to that cylinder. Or just have them all rebuilt.

Would injectors cause vibration at a specific rpm like that? With that in mind, I suspected the problem to be "deeper". I guess with the high mileage, I sometimes expect the worse. Have you witnessed similar symptoms at some time?

As soon as I can get ahold of new heat shields, I will take a look at the injectors.

Funny you should mention this. The 603 seems to exhibit the same phenomena. Around 2000 rpm, under load, it has just a bit of vibration. It goes away at 2300 and is not apparent at light loads at any speeds.

Quite strange. Not serious enough to attempt to isolate, however.

Nailing and smoke = injector system.

I think the IP itself, or its governor system, is the last place to look.

First things to check and test.

Valve clearances. Not difficult or expensive, couldn't hurt, and could tell a story.

Injector spray pattern and pop pressure. Unbalance in injectors can cause unbalance in firing and uneven torque pulsing, or vibration.

Delivery valve seal and pressure build up in injector line. Failure to build to 'pop' pressure rapidly can cause late injection, and if it's in one or two injectors only, the above unbalance in firing and torque pulsing.

Best Regards,
Jim