Oil Pressure and Temperature - Final

world's most dangerous man

Before we begin, my heart aches as I watch my beloved country descending into ruin. I generally try to avoid politics in this blog, but we all eventually reach a point where we can hold our silence no longer. The absence of leadership, and the propensity for the current White House occupant to throw gas on a fire are exacerbating our national catastrophe. A disbeliever attitude towards a pandemic has gotten everyone anxious as well as over 100,000 Americans killed. Add 40 million unemployed people (many of whom are not getting their promised checks) who are going hungry and are going to get upset, looking for an outlet. Add to that what appears to be police conduct inconsistencies (white folks with guns can stop ambulances from getting to the hospital, but Black and Brown folks can't just walk down the street armed with only signs). Add an elected official directing tear gas and rubber bullets at unarmed protesters so he can have a photo-shoot outside a church after threatening our citizens with military forces. The people want leadership; we want answers. After all this, we demand, and frankly deserve, a change. Okay, back to the usual chaos oasis: car stuff.

I have been slowly working through a gauge solution for the oil system in the TDI conversion (For reference, see Oil and Temperature 1, 2, 3, 4 and 5). This really has been interesting, and I think those running a stock air-cooled motor might want to do something similar. Since the air-cooled engine runs oil hotter, the broader range gauge may work better, which means less work for you. I unfortunately did not take any pictures of the final steps setting up or installing the Porsche combination gauge. My phone died, so while it sat on the charger I readied the dashpod. Then, assembly inside the bus required 3 hands so I couldn't get a picture without risking dropping something. So, please try to use your imagination as I describe the final assembly.

Final Gauge Prep - Bulbs

When I left off last, I had the new 250*F limit temperature innards swapped out, and that half of the gauge re-installed into the gauge. We were entering the home stretch. I focused on the bulbs next. There are 4: one each for illuminating the two gauges and one each for the 2 new idiot lights (Alt and Oil). Now, I don't have the light wired at the alternator, but I figured if I could get the gauge-end ready, it would be one fewer thing to fiddle with later. The illumination lights are simple push-and-twist 1.2W bulbs like the others in the bus dash. In fact, they are the exact same bulb. The idiot lights, however, are not like those, nor are they the same size. The alternator bulb is bigger, and the oil pressure light is an odd spade style. As luck would have it, back when I replaced the thermostat panel bulb in Flash, I had to buy a 2-pack of bulbs. That bulb (Sylvania 2721) was a match for the oil pressure bulb socket. Kismet!

Final Gauge Prep - Wiring
With the bulbs set, I shifted to the wiring. There are 4 signal wires (oil temp, oil pressure, oil warning and alt warning). For these, I simply stripped the wire ends. They already have disconnects at the gauge so I could disconnect them later when I pull the dashpod. The other wires (1 ground, 2 illumination and 2 switched 12V) needed a different treatment. In the interest of keeping the dashpod remove-able, I wired the 2 switched 12V source wires into a single male disconnect. I did the same for the 2 illumination wires. To the ground, I attached a female disconnect. Before I moved out to the bus, I fiddled with the gauge to make sure it was straight up/down.

In the Bus

warming up

The dashpod re-mounts similar to how it came out: slide it under the steering wheel from the center, near the stick shift, face down. Rotate the guts towards the hole. With the combo gauge in the third hole, this is a little harder, but not by much. Now, the hard part begins. I started with the illumination wire that was in the bus, cutting the end off that goes on the passenger-side end of the dashpod. I spliced in another wire with a female disconnect on the end as well as that original wire that I had just cut off. This gave an illumination signal that the combo gauge could plug into. Then, I started plugging in all the things that were there before... the grounds, fuel gauge, turn signals, and the low beam / hi beam and, of course, the illumination bulbs. Before I took any more steps, I tested things by turning the key to run, and flipping various switches to see the bulbs light up. Satisfied I had done no harm, I shifted to the new gauge wiring.

I started by inserting one of those "chair" disconnect splitters into one of the dashpod grounds and then connecting the ground wire from the combo-gauge. I then used my wire color map from my last post, heat-shrink splicing the gauge signal wires to the cable wires. Then, I plugged in the illumination male:female. Last, I sourced switched 12V with a covered female disconnect, and plugged in the male from the gauge. I thought about wiring it into the black switched circuit that powers the fuel gauge and the turn signals, but couldn't get my head around how to do it with one of those chair disconnect splitters without risking an accidental grounding. I wanted to minimize the wire cuts too. Last, I could have just put disconnects on the ends of the colored wires rather than splice into the original gauge wires; I just didn't. I still might.

thermostat just opening

The location of the new gauge interrupts the wire-flow for the brake warning light. I will need to extend those wires, or change the warning light location. Since we are still semi-restricted for CoViD-19, I won't be driving any great distance terribly soon, so I have time to resolve it. I found it interesting how much tension was on these wires, though; curious that there was no wiggle room on them. That was true when I went to remove the dashpod at the start of all this as well. Looking back, it was an issue when I went trying to figure out what was up with the fuel gauge years ago. In fact, removing the dashpod this time involved moving the wires one by one through the hole, while placing considerable tension on the wire, so I wouldn't mess up the wires during removal.

Unrelated, the couple of hours I spent in the bus getting the dashpod wired and installed I also test-ran the little heater with the new Afterburner thermostat. Once I had the temperature probe in a spot where it was not up against the outside wall, the thermostat held the interior temperature at a fairly static 70*F. Considering the wind and rain outside, it was really luxurious. Imagine how different the experience is compared to lying in the street gutter trying to get an alternator swapped out in front of that old Lake Oswego house.... in a late fall rainstorm. We've come a long way, Hapy.

Testing

after thermostat opened

With the wiring complete, I slid the dashpod into the hole. I found that the washers that are helping to hold the combo gauge to the dashpod will hang-up on the hole if you are not careful when you remove the dashpod. I will think about how to construct something to hold the gauge on better. Anyway, once roughed into place, the 4 Phillips screws will get it into the right position. Once locked down, I re-tested the system by flipping the key to run. The gauges lifted off of their bottom position just like they did on the kitchen table during the tests. This told me that the round-trip for the 2 circuits was good. Then, I turned on the lights and I could see the gauges illuminated. The oil warning light popped on, but the Alt light did not. This was all as I expected. Next, a test fire of the engine, and maybe a little cul-de-sac parade to get the gauges to move. First, of course, thread the speedo cable into the back of the speedometer.

Because of continued limp-mode issues, I ran my engine-running tests in my driveway. That made the picture-taking possible, though. The gauges respond as I would have expected. The oil pressure starts high when the engine is first started and then settles down once the engine is warm. The oil temp warms faster than the coolant. When I rev the engine up and down, the oil temp climbs and then settles. My last test was to check under the bus for fresh oil spots. There were none. You can see from the pictures what the coolant temperature is (number in lower left corner of UltraGauge).

With that, the oil system gauging is complete. I am not sure what's next. I have a cable for re-wiring the front-to-back stuff, and otherwise I'm just about running out of parts for projects. I do have some coolant hose and a stretch of aluminum pipe, though, so maybe I'll get after some part of the defroster. Of course, some day I'll have to get back to paint-prepping Zed, the 1979 280ZX. I'll figure it out when I get to the garage. Thanks, as always for following along--