Well after all kinds of searching:
Injector Pop Testing, looking for leaks, retarding my timing etc... etc... I finally cured the shake at idle in my 87 300d.
This thing on a long trip when the engine is good and hot would shake so bad at idle that my knees would move a good 2 inches left and right. At a cruising speed it was fine. Just idling.
I thought I was going to have to have the injection pump rebuilt!
FINALLY figured it out. I had read the 603's IP is just not as stout as the 617... that didn't make sense to me because component wise it's very similar. Also I'd heard the Cummins 12 Valve trucks from 94-98 with the inline pump (much like ours) would last 800k and more before rebuild. So to think mine needed to be rebuilt really had me bummed out.
Anyways, after all this I ended up having to take my IP out anyways because I created an oil leak between the pump and the block (o-ring) while adjusting the timing. So out it came (see the pictorial I did a while back).
But while it was out I decided to change all the seals (bottom o-ring, side plate rubber gasket, ELR O-ring, the back plate gasket, as well as the Fuel delivery valve o-rings and copper washers).
The only ones out of that
AFAIK that have anything to do with fuel delivery are the delivery valve o-rings. So at this point I'm thinking that had to be it.
If your engine shakes at idle and is a 60x (300d '87-94, E300d '95-99, '86-?? 300SDL) I would bet money that it's your delivery valve o-rings.
I didn't see ANY sign of leaking but when they were removed they were flat and hard as could be. I'm amazed they weren't weeping. At the high delivery pressure of the injectors probably just a little bit of leaking pressure makes a big difference at idle. I haven't confirmed this twice yet but I think I've also broken the 30MPG marker (hwy)!
So... this has been a great fix. I've been wondering what it was for a long time. From now on I'm not going to let anyone tell me the 60x injection pumps are not as good in quality as the 61x IPs. But I guess they do have one thing on us... 61x's didn't have o-ring seals at the delivery valves.
Anyways, I've now confirmed with an 8 hour drive (very hot today at 107F) that the shakes are now gone after my o-ring job.
Buy the splined socket, buy the viton o-rings from JADAVIS on the forum and do the job if you haven't. The
www.DieselGiant.com tutorial is a pretty good step by step if you're confused about it.
One thing I will recommend is to remove the splined locking colars (keep the Delivery Valves from turning when you tighten or loosen the injector lines) before cleaning the top of the IP because under them is more crud. I used brake cleaner (2 cans) and a nylon brush to remove the gunk before I did the job. Clean is important.