Diesel Dumping Discontinued

In my last post, I discovered that the injection pump was leaking fairly badly. Today's brief post covers my replacing the 2 top seals.

Symptoms

If you don't open your hood very often, especially while the engine is running, any leak may not be obvious. With the engine under the rear deck, and the rear deck often having stuff on it, I hadn't seen the leaks evolve. On my last few drives, I had smelled diesel fuel, and I had made a mental note of it. Honestly, I thought it was related to the now-not-operational furnace which still had a diesel line filled with diesel running to it. I suspect I fueled with something which was not B20 and that caused the seals to shrink. Recall, I wanted to run the air out of the new heater so I popped open the rear-deck engine lid (I cut in years ago) and fired up the engine. I walked to the back of the bus and could see fuel dumping down the sides of the injection pump. I dashed to the driver seat and turned off the engine. Returning to the engine bay, I added coolant, but tried to figure out where the fuel was coming from. It looked like it was coming from the black plug on the side, and maybe out of the edge along the top on the opposite side. The top seals had finally shrunk to the point of being compromised.

DieselGeek

There are lots of sources for seals and seal kits, but IMHO, the best is from DieselGeek (like here). The operator is a TDI owner and only sells things he actually uses. His opinions are highly regarded on Fred's TDICLub forum too. The kit is complete; and you will want to include an anti-tamper socket (here) to get that one fastener removed. His product page contains a link to a complete how-to (also linked here) that will take you through the process. Since it is so well documented, I will not repeat it here. I will only highlight things that I discovered that either differ or underscore that documentation.

Clean and Mark Pump Location

After ordering the kit, I went out to Hapy and cleaned outer case of the Injecion Pump with degreaser. I paid special attention to the seams where the seals would be replaced. Once clean and dry, I applied the JB Weld (as instructed) on 2 corners of the pump covering the lower seals both above and below. This will allow for a more precise re-location of the pump after the lower seal has been replaced. I also took a chisel and made a clear mark that crossed the seam. For good measure, I added lines with a Sharpie. Although diesel fuel can remove Sharpie lines, I did not suffer that fate.

Top Seal

Following the instructions, I replaced the top seal first. Before I started, I wrapped the Injection Pump below the lower seal with a ratty old towel to capture spilling diesel fuel. This turned out to be an unnecessary precaution, but when I need to replace these seals again, I will do the towel wrap again anyway. Better to be safe. I left the return fuel line attached and tilted the cover far enough so I could reach the old seal. With a watch-repair slotted screwdriver, I picked out the seal. It looked fine, but I did notice that it was practically flat with the edge of the cap, so I could imagine how it could be leaking. Once removed, the groove was perfectly clean. I gave it a cursory pass with a paper towel anyway and the new seal slid in perfectly. Before returning the cap to the pump, I noticed some gunk buildup on the black-plug side so I carefully scraped it off with a razor blade and then wiped it clean with a paper towel. It is little things like that which can prevent a complete seal.

Bottom Seal

The lower seal is a little tricky, but, again, the instructions were spot-on with only one exception: The Torx bolt holding the corner directly below the fuel return may not be easily addressed, depending on your tools. The picture below-right illustrates the issue. My Torx socket fits a 1/2" ratchet so it's rather thick. It is also kind of stubby, so the socket itself needs to occupy the space where the fuel return is. So, either have longer throw Torx sockets or do what I did: Remove the cap to remove and install that once fastener. Yes, that's a pain in the butt, but I found no alternative other than loosening the banjo bolt, and after the power steering debacle with Flash all those years ago, I want nothing to do with a banjo bolt if I can avoid it. I just went looking for the post and I can't find one. I can't believe I didn't post on the saga of replacing Flash's steering rack, like, 10 years ago. The banjo bolt was nearly the death of me; my thumb swelled up from applying pressure to get things bolted together... it was a nightmare.

Similar to the upper seal, once the unit was unbolted, the TDIClub documented process was spot-on. Even the "smack it with a bit of wood to crack the JB Weld worked as written. I did not remove the hose from the fuel return line, however. I just tipped the unit back far enough to remove the seal without fear of something dropping into the top of the pump. I also found some gunk build up along one side on this piece, like I did on the cover. So, I did the same thing: slowly scraping it clear and then cleaning the metal with a paper towel. With the seal in place, I again followed the instruction to make sure the little drive stick entered the hole on the piston (you can feel it locate) and set the unit in place, using the fracture lines in the JB Weld to position. Because of how thick the new seal is compared to the old one, there was some wiggle space in the fractures, so the extra marks, bot the chisel and the Sharpie, were necessary to get the unit in the right spot.

Because of the Torx socket challenge, I got 2 of the fasteners on, then removed the cover, put the other Torx fastener in place. At this point, I re-set the location of the top unit comparing the lines again. Then, I tightened down the 3 Torx bolts hand-tight. Since these are brass bolts going into aluminum, the threads can strip, so mind your torque settings (less than 8 ft-pounds). Content, I put the cover back on, added the anti-tamper bolt and the cover Torx bolts.

Testing

At this point, it is recommended to prime the system with a MityVac. I read some comments by users who did not need to do so. I thought I would try starting before getting into the hand-vac, and Hapy fired right up. I walked around to the back and there were no leaks, and he idled nicely around 903 rpm like always. The test for whether the little drive-stick is in place is simply to try the accelerator. If the engine RPM's change, it's in there. Success. So, we took a quick drive around the usual test loop. Hapy was responsive and slowly warmed up. As part of my test drive, I tried the heater.. that worked too! I could feel warm air blowing up through the defroster.

When I got home, I noticed that Hapy was having a harder time maintaining a consistent idle. He would drop down around 875 and go up around 950. I vaguely remember this being a thing for him and a quick tap on the accelerator settled him down. I don't know why this is a dynamic for him, but with the seals replaced he is acting exactly how he used to... without dumping fuel.

That's it for today. I hope to get after the furnace next. We'll see what the future holds. Thanks, as always, for following along-