It can be done. Bear with me this is long.....
My 89 F250 farm truck started leaking fuel out of the IP drive shaft weep hole on the bottom of the pump. Leaking really don’t describe it, it had almost a steady stream running out of it. The old truck runs really well, and I hated the thought of putting a rebuilt pump on it which had all the adjustments set back to the stock settings. The way she smokes and runs, I’m pretty sure that this IP had at least had the fuel screw turned up some when the ole truck followed me home.
I am a DIY kind of guy, and with a cheapo rebuilt IP starting at $350 or so, I really wanted to find out if there was a way that a I could replace the drive shaft seals myself. I figured it’s my pump and with a good manual I have been into some pretty detailed stuff before so why not. I figured if I mess this one up too bad, I do have another dead pump off my parts engine that I could use for a core if I had to go the rebuilt route.
So I started reading about everything I could find on here and other forums, and what I found wasn’t’ very encouraging. Every body says you just don’t mess around with an IP, that there are to many adjustments and settings to get out of whack. Well, I’m just not a guy who can take no for an answer, so I kept digging the web for info, primarily for some kind of service manual on these pumps. I finally found out that there is a Navistar service manual on the 7.3 IDI with in depth directions on rebuilding the Stanadyne DB2. The manual part number is Navistar CTS 4245G, Volume 2
I started searching the web and found an eBay seller offering volume 2 on a CD. (actually a 5 volume CD, the other volumes cover DT360, DT466 engines, etc) I bought the CD, opened volume 2 and found a PDF of an IH 7.3 IDI service manual with 423 pages! I haven’t even started looking at the engine rebuild, etc info. There is a whole section devoted to the DB2 with 26 pages on disassembly, 5 pages on inspection of parts, 28 pages on reassembly, and 13 pages on calibration. I noticed the eBay seller isn’t offering the CD right now, but I suppose they will as it was one of those multiple item type auctions. The whole CD cost less that $15 with shipping.
Next step was to find a seal kit, and good ole eBay came through again. For $31.00 including shipping I got everything I needed here:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&vxp=mtr&item=170855156259
So with this CD manual on my trusty laptop, I went to the shop and built a rotating holding fixture which mounts on my workbench, and after mounting the IP, I went to work on it. I will be the first to tell you that there are in fact numerous settings that have to be calibrated for it to perform correctly, but my thought was that if I could mark/measure these accurately, I should be able to reinstall them in the same position. What I found was that to take her apart to the point that you can get to the driveshaft snap ring and pull the shaft out, there is really only 2 calibrations you have to concern yourself with. 1 is the position of the face cam (advance cam) on the throttle shaft. It is just simply clamped on the shaft and wherever you lock it down is where it is. There is no key, no spline, etc. So I just marked it lightly with a chisel to line up with the roll pin that is driven through the end of the shaft , and was able to put it back on exactly like it came off.
The other calibration is the allen head guide stud which inserts into the mini-max governor rod assembly. It screws into front of the upper box shaped part of the pump housing on the fuel lines end, right above the little lock plate and screw that locks the transfer pump end cap in place. I just measured how far out of the housing the stud protruded with my caliper, and lightly chisel marked the top of it so that I could reinstall it back in the exact same spot it was before. The most important thing is to go slow and think/measure/mark anything that has some sort of calibration before you start messing with it.
I finished my reassembly and I got the pump installed back on the truck. After cranking for a while, (these IDIs take some time to bleed the injectors), she finally coughed, and I bled it some more, hit the manual glow plug button for a few seconds and she fired up. I went for a short drive and it is running great, and NOT LEAKING ANYMORE!!!
The outlook I have on all this is that if you are a person who can follow directions, take your time, and be fanatically clean and careful with precision parts, then you can take this manual and satisfactorily disassemble, inspect and reassemble a Stanadyne DB2 pump.
They do call for a few special tools, like a seal expander to install the new drive shaft seals over the shaft, but I made it fine without them. I just took my time and was able to work the seals in place by hand without much trouble. The only “special” tool I used was a little wire hook I made to hold the fuel shutoff solenoid plunger back while installing the top cover. And, the manual showed me how it needed to be shaped. Other than that it was just an inch lb torque wrench, snap ring pliers and ordinary hand tools and allen wrenches.
Hope this helps someone, and I hope I haven’t put anyone to sleep…..J