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-

Adventures with Nemo

No, this isn't a post about a clown fish. Today, I'm going to cover the adventure of trying to get Nemo, T's A4, to operate correctly again.

Break Down
This story actually starts very soon after the last post about A4 ended (See A4 Puzzles). It was late Summer, and T had been living with us for a while. His car had been behaving well, but he wanted to make sure everything was tip-top before leaving for Eugene. Well, we got it running, but he broke down with a coolant leak on the way to Eugene. We knew the radiator had a small leak, and we concluded that the leak was the cause. I drop-shipped him a replacement which he installed in his garage. Unfortunately, this was not the cause of his coolant loss.
T replaced the coolant outlet flange. Twice.
He replaced a few hoses.
He swapped the coolant overflow bottle with a used one from the junk yard.
By the end, he was no longer seeing coolant puddles appear under the car, but when he would return from a drive the coolant bottle would register below "MIN". Frustrated, he had the car towed home, to Beavo. He rode with the tow truck driver and borrowed Flash while K2 and I assured him that we would find the cause and fix it.
That was in June.

Rad Patch

K2 was out of school and missing his daily shop time, so we thought he would get into fixing the A4. Well, that didn't last very long as Summer brings its own distractions and rewards. So, while he took some air, I re-assembled what K2 had started (he was preparing for a head-gasket job) and got Nemo to start again. I had forgotten that I had drop-shipped a radiator down to Eugene, so I started to disassemble the front to remove it. I discovered that one of the fasteners holding the air conditioning condenser to the radiator was a screw instead of a bolt. AND, the tip of the screw had pierced the plastic side-tank on the radiator, causing a leak. So, I started with that.
I used an old Shade Tree trick for small (read: pin) holes. Do NOT do this for a hole of any significant size because the superglue could get inside the radiator rendering it less effective or even completely ineffective. Anyway, the quick fix for tiny holes:
drain the coolant down below the small hole and make sure the area is dry.
rough it up a little bit with sandpaper or a file
apply superglue, covering the hole
dust baking soda on top of the superglue, completely covering it
once dry, blow off excess baking soda
fill system with coolant/distilled water mixture and pressure test
Yes, it actually works. Again, this is only recommended for very small holes. There are epoxy-based kits that are designed for larger holes. At some point, though, even those become ineffective and you need to replace the whole thing.

Puddles
This worked great. No more leak from the radiator. But other puddles still appeared after a spirited test drive and the coolant in the bottle read below "MIN". Well, that's familiar. In fact, it is the exact experience that T was having. At least we're back to what he was seeing, and the pin hole in the radiator was not the cause. I found the coolant dripping from the lower radiator hose, which appeared to have been replaced with one from NAPA. I replaced it again with a Continental hose, and cinched the hose clamps down nice and tight. Another spirited drive and another drip-drip-drip, landing in the same spot. I could hear a "pssss" sound, and traced it to a hose near the intake where I could see water bubbling around it. I tightened it up and then started tightening every hose I could reach. I tightened the thermostat cover as well.

Temperature Sensor

During my early test drive, I noticed that the coolant temperature gauge wasn't working. This is often diagnosed as the sensor being bad. I knew we had recently replaced it, but I replaced it anyway. That didn't fix it. While installing, I noticed that the 4-plug socket that plugged into the sensor had a frayed the brown wire. When I tested continuity between that wire and the other end of the gauge-sending side of the socket, I got continuity at the wire (which had a bare spot), but not at the socket. So, I knew the socket was bad. But, where do you find a 4-pin socket with the correct alignment grooves? On eBarf. I cut off the old plug, leaving a short length at the socket for reference and as much wire in the loom as I could. One at a time, I checked and re-checked as I connected the wires with crimp-on butt-connectors and then heat-shrink'd the connections. It plugged in easily and with the hoses tightened, it was ready to test drive. If you replace a plug like this, take care to wire it correctly or you could fry your ECU. No, I didn't, but I was full-on scared about it until I turned the ignition to run and saw the coolant temp appear on my OBD-II reader.

Leak Free

I took a familiar drive up the connector streets onto the main road, thundered down that main road, right at the major intersection, around the next main road to the connector streets on the other side of the neighborhood before returning home. This route has stop and starts, speeds up to 45mph as well as lots of turns and speed bumps. All while remaining within 1/2 mile of the house. By the time I got home, the temperature had gotten up high enough for the thermostat to open. I backed into the drive, pulled the hood latch and hopped out. I couldn't hear any "psss" noise and there was a single drip from the lower radiator hose. I figured that drip could have been residual from prior leaks, and a longer test drive was needed before I called it fixed.

Coolant Bottle Swap
I decided to replace the coolant bottle since I knew the one that was in was not exactly right. The bottle fit the mounting points, but the low-coolant-level sensor was rectangular instead of round, so the sensor wasn't plugged in. When you know you have a coolant leak, that's not a good set up. I drained enough coolant out of the old bottle so I could swap them out, but I did not fully bleed the air. Once re-filled, I got distracted, and left it filled, but un-bled.

Another Drive

The opportunity for a longer drive appeared the following weekend when T stopped by after helping his mom with some chores. He was eager to see how Nemo was progressing, so we pulled him out and took a drive, T behind the wheel. T was thrilled to feel the big turbo spin up (PO upgraded it) and hug the turns (PO upgraded suspension too). By the time we got home, we had been running at normal temperatures for probably 10 minutes. When we got home, we both realized that we couldn't smell coolant, and I mean not at all. Not a whiff. All prior drives had at least a small smell, so this was a really good sign. We popped the hood and saw that the coolant bottle was down to just above MIN. Recognizing this could have been because I failed to bleed the air, we figured we would wait until it was cool again before checking. We also discovered that the tail lights were not illuminating with the headlights. I'll need to fix that before T takes the car back to Eugene.

Bad News
So, I seized upon an opportunity to drive Nemo when I had to take a run to Tualatin. That's a 20+ minute drive with a mix of highways and surface streets, so it would be a good test. When I arrived at my destination, the coolant bottle was pretty much empty. I let the car cool down and then added some water, and drove back home. When I got home, the bottle, again, was nearly empty. I wanted to prove that the system wasn't leaking. So, I grabbed my MityVac. When I removed the overflow bottle cap to refill the water, I could distinctly smell exhaust as the pressure released. I was starting to conclude that the head gasket or head were allowing water into the exhaust. To confirm there were no other leaks, I removed one of the hoses from the bottle, plugged where the hose came from and applied 14psi of pressure to the cooling system. Over the course of several minutes, the pressure would drop by 1/2 psi, and no coolant was appearing anywhere. More reason to believe the coolant is traveling into the combustion chamber. So, my next task, which I will document separately, will be to remove the head, have it tested and then replace the head gasket.

This is a big job. Just for context, I got a quote from a mobile mechanic I've never used, and he came back with $1250US. Seeing that the quote is more than we could get if we sold the car if it didn't have this problem, we're doing it ourselves. Well, myself. I really would rather not spend my autumn working on the A4. I would rather combine efforts with C and dedicate ourselves to the Zed (1979 280ZX), completing the sand-down and possibly spraying primer before the temperatures get too cold to paint. Oh well.

It has been unseasonably cold for more than 3 weeks (10F* / 6*C or more below average), so the window for spraying primer may have closed and it may make the Nemo work a little less fun. Regardless, I probably will not have much time to get back to Hapy until dead-of-winter. I may delay the electrical re-do I had in mind and focus instead on recovering the front seats, since I can do that indoors where its warm and dry. We'll see how I feel and how the weather behaves when the time presents itself.

Thanks, as always, for following along.