When at the dragstrip for testing, trying to determine whether Project 325 had cooled down for another quarter-mile run, I decided I needed some gauges. Real gauges, with real numbers on them. An idiot light and a blue zone followed by a red zone indicating a probable need for engine replacement are no substitute for actual numbers.
BMP Design is one of several companies marketing a gauge panel to replace the E36's factory sunglass holder. Like others, its standard kit includes oil pressure, oil temperature and electrical system voltage. BMP uses VDO Vision Design electrical instruments, which I like. Many aftermarket instruments look like they should be hose-clamped to the steering column of an El Camino, but VDO gauges look just like the factory instruments in the last four decades of Porsches, because that's what they are.
Electrical system voltage is less important to me than coolant temperature, which was the impetus for this whole task. The factory gauge indicates normal when the car is just warmed up and stays at normal until it's really hot. At my request, BMP built a console just for Project 325 with a water temperature gauge in place of the voltage gauge.
I thought it would be fairly easy to install the gauges, based on the instructions, but it took me about 18 hours. I also added features, installing Rogue Engineering adapters and VDO senders in the transmission and differential and wiring a switch to change the oil temperature reading between engine, trans and diff. I'm anal and take the time to be sure things are done as well as possible, but this job was seriously a pain. You'll have to drain some or all of the liquid from whatever systems' temperatures you are measuring, which meant I changed engine, trans and diff lubes as well as drooling out some BMW blue coolant. If you're using synthetics, you may want to plan farther ahead than I did or save it for the next change interval.
Factory wiring is very well integrated. It's protected from mechanical damage and hidden from view. Running most of the gauge wires where they would go in an ideal world would mean disassembling much of the vehicle, so I ended up running wires where they weren't meant to be. To get away with that, I had to armor the heck out of them, but I still ended up with zip ties and funky colors all over the place under the car. It's less than ideal in some respects, but now I can properly monitor the driveline, which is better than before. Over the last few months, I've also been working on horsepower and further refining the suspension. Those are being sorted out gradually, and the results are promising.
|At a Glance|
|Estimated time:||'18 hours|
|Costs:||BMP Design gauge console kit: $359.95,Rogue Engineering drain plug adapters: $25.00, Extra senders: $24.00, Synthetic lubricants,11 quarts: $70.00, Wiring and wiring accessories: $30.00|
The box from BMP Design contained a factory sunglass holder with the pocket modified to mount gauges, plus required senders and adapters. Additional electrical connectors and instructions were also included.
The box from BMP Design contained a factory sunglass holder with the pocket modified to mo
BMP had pre-wired the three gauges and heat-shrinked the 18-gauge wires to protect them, making this a fairly slick little kit. I had to adjust one of the U-brackets to be happy. When a few of the wires came out of the terminals with normal handling, I realized that the insulated terminals were crimped with a tool intended for uninsulated terminals. It's definitely an oops but not a hard problem to fix.
BMP had pre-wired the three gauges and heat-shrinked the 18-gauge wires to protect them, m
Rogue Engineering provided adapter plugs to install 1/8 NPT-threaded VDO temperature senders in the trans and diff drain plugs. The VDO sender included with the gauges replaces the engine oil drain plug directly. I bought extra senders, as well as Red Line oils, from McKenzie's Performance Products. I routed the differential sensor wire alongside ABS sensor wiring for a while, then the rear brake line. I wouldn't tie any electrical wire, even very low-powered, to a fuel line.
Rogue Engineering provided adapter plugs to install 1/8 NPT-threaded VDO temperature sende
I bought a rotary switch at the local electronics supply store (forget Radio Shack) and mounted it in one of the blanking plates below the gauges. It changes the oil temperature signal between engine, trans and diff.
I bought a rotary switch at the local electronics supply store (forget Radio Shack) and mo
The VDO oil pressure sender, threaded into the included adapter, replaces the factory oil pressure switch on the back of the oil filter housing.
The VDO oil pressure sender, threaded into the included adapter, replaces the factory oil
To put your 24mm deep socket and ratchet on the oil pressure switch, you must remove the alternator cooling duct, HFM and intake manifold support bracket. I stuffed a paper towel in the alternator cooling duct so I wouldn't drop hardware or tools into it. Do this while the engine oil is drained (necessary to install the temperature sender, which replaces the engine oil drain plug). I placed a small funnel with a long tube on it to catch oil that leaked out when the pressure switch was removed, but it was only a few drops.
To put your 24mm deep socket and ratchet on the oil pressure switch, you must remove the a
Don't forget the metal sealing washers when installing the oil pressure sender adapter, and a little Teflon(R) tape to seal the 1/8 NPT connection to the sender itself. I jumpered the pressure switch connector to the screw terminal and wire-tied the connector to the sender body. It's ugly, but the alternative was to cut the factory wire or wrap it in a ball of electrical tape. I ran the wires for oil pressure and coolant temperature together, following the intake manifold support brackets and finally the oxygen sensor wire toward the middle of the car.
Don't forget the metal sealing washers when installing the oil pressure sender adapter, an
I bought several colors of high-quality, 16-gauge wire with 600v, 105*C insulation. Nylon spiral wrap is the best way to armor the wire and should be used anywhere it is near a rough surface, sharp edge or is wire-tied to anything else. Spiral wrap can also be used to bundle wires into a harness, but split-sleeve loom can be faster and allows wires to be added or removed in the future. The downsides are it's bulky and ugly and requires wire ties or electrical tape to hold it in place on the harness and control where wires enter and leave it. Zip-Tie(R) is a trademarked brand name for a particular style of nylon wire tie. I prefer made-in-U.S.A., Thomas & Betts wire ties to the cheap, made-in-China kinds often available in bulk selections. Material quality and dimensional control cost a little more but matter in the long term.
I bought several colors of high-quality, 16-gauge wire with 600v, 105*C insulation. Nylon
The coolant temperature sender supplied by BMP can be threaded into the cylinder head. The Bentley manual indicated the location of the fitting incorrectly. I found the intended location but couldn't get a wrench on it without removing the intake manifold. In an ideal world, I'd weld a bung to the thin aluminum thermostat housing and thread the coolant temperature sensor into it. In this world, I'll probably just do what SCC's Dave Coleman did on his rally car: insert a tee fitting into a radiator hose. I couldn't source one between the time I settled on this solution and deadline, but Dave said the Autobacs store not too far from our office has the fittings.
The coolant temperature sender supplied by BMP can be threaded into the cylinder head. The
BMP suggests drawing power for the gauge console from a wire at the headlight switch. Use the wiring diagrams in your Bentley manual to determine which ones are "Hot in RUN and START." I ran the wire to the gauges between this smooth, metal panel and its soft, padded cover, taping it to make sure it didn't move to a sharp edge. At first, it seems every possible place to snake a wire from the gauge area out to the side is already full of wires, but I was able to feed a piece of coat hanger wire in from the area shown here and tape the power wire to its end. Be careful not to damage existing wires; almost no force is required in the right place.
BMP suggests drawing power for the gauge console from a wire at the headlight switch. Use
BMP includes several 3M Scotchlok(R) connectors. One is used for the power connection, and the instructions say to use one to tap into the cigarette lighter ground. However, the mismatch in wire gauges meant there was no electrical connection.
BMP includes several 3M Scotchlok(R) connectors. One is used for the power connection, and
Instead, I used this piggyback spade connector, which connects the instruments to the lighter ground and provides a second tab for the lighter's original ground to connect. With this, the gauges had power. Instructions also suggested drawing power for the instrument lights from a circuit that's already dimmed with the factory instruments, such as the lighter's bezel light. I'm not sure whether that's a bad idea or Project 325 has a problem with that circuit, but after some time spent characterizing the available power with a voltmeter, I established that was not going to work. With more time I'd have gone to the dimmer switch, but to get the job done I simply hooked the gauge lights to the gauge power. They are lit any time the car is on, but it's not bothering me too much yet.
Instead, I used this piggyback spade connector, which connects the instruments to the ligh
To avoid removing the intake manifold and dash to expose where the wiring harness passes through the firewall, I brought the signal wires up through the rubber shifter surround. They pass by the driveshaft, which is less than ideal, but I was careful to tie them securely to the side of the tunnel and armor them with split loom. The clearance is a couple inches, so I'm confident it won't be a problem. I connectorized all the lines with fully insulated spade connectors, so the console can be removed as a unit without disturbing the wires past this point. I labeled both sides with a Brother P-Touch label maker, a past "Tool of the Month."
To avoid removing the intake manifold and dash to expose where the wiring harness passes t
The on-board computer clips into place above the sunglass holder, the raised ridge engaging the metal clip on the holder. It is removed by reaching through the hole, disengaging the ridge from the clip and pushing outward. That's easier said than done even normally. With the gauges installed, it will require a flat metal blade of some sort and a whole lot of finesse. I could find no visible damage, or broken clips, but the rear portion of the on-board computer was reluctant to stay attached to the front after I removed it. The tape seems to be working (it's only 4 days so far). Don't put the on-board computer back in before you're absolutely sure the gauges are all working right.
The on-board computer clips into place above the sunglass holder, the raised ridge engagin
The VDO gauges blend nicely with the interior, as does the textured plastic panel they're mounted in.
The VDO gauges blend nicely with the interior, as does the textured plastic panel they're