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.