Do Not Post Questions In This Forum!!! [Archive] - Bimmerforums

Mr.M

01-20-2008, 06:30 PM

CAN SOMEONE PUT THIS POST AS IT'S OWN THREAD IN THIS FORUM?

****This write up is a work in progress, and is not yet finished (pics not up yet)****

Ultimate Aftermarket Gauge FAQ and DIY

So I am not an expert or anything, but there wasn't one thread that did it all for me when I was looking to install aftermarket gauges. So I'm making one ;) Everything in this thread is about doing it all from scratch. Not paying the ludicrous $108 for the gauge panel or getting fleeced by paying $450 for a gauge kit. I did everything myself for under $250, and you can too :buttrock

I tried to make this DIY as thourough and as simple as possible. If I insult you by telling you how to remove the glovebox, I am sorry, as this DIY was intended for use by a total newb who's never worked on anything. My last DIY (M42 ICV clean) was like this and it got positive response, so from now on any DIY's I write will be exhaustively detailed. Hopefully this will clear up choosing, buying, installing, and using aftermarket gauges and save you some time and money as well :buttrock

GENERAL DISCUSSION:

I mounted my gauges in the sunglass holder, so everything in this DIY is tailored towards that, though almost all of it would be applicable to mounting them elsewhere. So basically here's how the gauge thing works. At whatever point you insert it, a sending unit gathers information about whatever it is you're trying to measure. The sending units are often meant to be attached in a manner that will provide a good ground (like tapping the thermostat housing.) One wire will leave the sending unit and connect to the gauge itself. The gauge will also tap into a 12V power supply and a ground. The 12V power supply needs to be switched and the ground dedicated and solid. I will discuss why later.

If the gauge is lighted, a 12V lighting source (like the illumination for the CD player or the cigarette lighter) is needed as well as a ground. A good ground is not as necessary here and can be done in parallel. I will discuss this later as well.

WHAT TO BUY:

The first step in all of this is determining what gauges you want to install. Most kits are oil pressure, oil temperature, and voltage. I found voltage to be useless, as my battery and alternator were recently placed. I thought it much more wise to have water temperature, which will tell me if the notoriously unreliable coolant system is about to fail. When it comes time to do the fan delete, the water temp gauge will be the ultimate verdict as well. I wanted oil temp so I would know when I could go WOT after warm up, and to keep watch at the track (when I finally go! :shifty) I wanted oil pressure because I wanted to see that the oil pump was working, that the nut had not fallen off, etc.

After that, it was time to buy gauges. I went with VDO vision, because they were only $25, had black faces, which text, and were backlit in a color that is almost identical to the stock BMW amber. They basically have a stock appearance unlike the white faced autometer gauges. Because I went with VDO gauges, I decided to go with VDO senders to ensure compatibility. Next I needed to find out where I would mount the senders.

For the water temp, I wanted to get the temp at the highest point – water coming out of the engine block. If boiling, 500 degree water was coming out of the block, I would know I was in trouble. So, on the M42, the right side of the thermostat, which connects to the upper radiator hose, was where the party was at. For the oil pressure, either an oil distribution block (ODB) or an oil center was needed. The ODB is a piece available from JT designs for $105, and has a port for the oil temp, oil pressure, and one spare. Do a search to find more. Then there is the UUC oil center, which just replaces the cover to the oil filter. I chose the oil center because people have had problems with leaking ODB's, the UUC product was $5 cheaper, and it fit ALL E36's, where, IIRC, the ODB only fits 6 cyl's and I have a lowly 318 :shifty. The Oil Center also looked much easier to install.

The oil center is tapped with a 1/8-27 NPT (national pipe thread.) This is the most commonly used thread pitch. I went to summit racing to get the gauges and sending units, because they have insanely fast shipping and are usually the cheapest. I went with electrical gauges because they were cheaper. For oil pressure there were 0-80, 0-100, and 0-150 Psi gauges. I went with 0-100 because it matched the range of the corresponding sending unit. The only real reason to choose either is visual appeal. The same applies to the water and oil temp gauges. When it came to buy sending units, I bought the standard temp sender (1/8-27 NPT thread pitch) which would fit perfect into the oil center. I did not need to buy the adapter kit for the pressure sender because it was also 1/8-27 NPT. I did however, need to buy a 1/8-27 NPT for tapping the thermostat housing.

The next step was getting all the other crap I needed. VDO calls for 16 gauge wire for the gauge power supply, the connection between the gauge and the sender, and for the lighting. HOWEVER 14 GAUGE (thicker) WIRE IS REQUIRED FOR THE GROUND. This is extremely important as an imperfect ground will offset the readings and make them false. For the lighting, this isn't a big deal, but for the gauges it is essential. I ran to Kragen and picked up 3 spools of wire: one brown 14 gauge for the ground (brown is BMW's color for ground wire), one white 16 gauge, and, stupidly, one red 14 gauge :shifty. I thought the package said 16 gauge - srsly. Lastly, I need connectors and electrical tape. I bought female connectors that fit on the male tabs of the gauges. See DIY part for pictures.

COST:
So far the cost breaks down as follows:

VDO Gauges: $25 x 3 = $75

VDO Temp Senders: $8 x 2 = $16

VDO Pressure Sender: $26 x 1 = $26

Oil Center: $100 x 1 = $100

Wire: $3 x 3 spools = $9

Tape: $3 x 1 = $3

Connectors: $3 for 20 pack = $3
1/8-27 NPT Tap: $17 x 1 = $17
11/32" Drill Bit: $5 x 1 = $5
TOTAL: $232, not including shipping or tools :buttrock

TOTAL: $254, not including shipping, but including tools
This is much cheaper than the $350-$450 people charge for kits you still have to install yourself.

The oil center came from UUC, the VDO stuff from summit racing, and everything else was bought at Kragen. The tap did come from Napa auto parts though.

Lastly, was the gauge panel. $108 or even $75 is a retarded price to pay for a panel to hold gauges. I'm still in college, so I wanted to save a few bucks. I own a dremel (:alright) so I cut out the back of the sunglass holder to accommodate the gauges. Cut it as you see fit, but leave a box frame on the outside. You'll need to adhere the gauge panel itself. Right now, this DIY will include a gauge panel made out of a ceral box (Cinnamon Toast Crunch FTMFW). I have access to a machine and composites lab at school, so when I return I will either machine an aluminum panel, or make one out of carbon. Maybe I'll make a bunch of them and sell them for a small (or large :stickoutt) profit . . . I'll update the thread when I get the "real" panel done. But for now, the cereal box is working fine :buttrock Now we know everything about what we're doing, how, and why. The picture below is basically what I want to do (I made it in class while bored), but the piece in the picture is not the right size so I didn't use it. I would obviously cut holes in it and clean up the edges.

http://i111.photobucket.com/albums/n130/AeroGT3RedWing/carbonfiber.jpg

Time for the install:

DIY/WRITE-UP:

After I ordered everything, I waited all of 3 days for everything to come in. :alright I took the sunglass holder out first. To do this, you first remove the OBC by feeling the top of the sunglass holder until you come across a small hole. Reach in that hole and push the OBC out. Move the OBC to the side. If you have seat warmers, an alarm LED, or any other electrical connections going into the little plastic tabs (see picture below), remove them and slide them into the center console underneath the sunglass holder.

****PICTURE COMING****

Then pull the sunglass holder out, and remove the electrical connections to the cigarette lighter. With the sunglass holder out, it's time to saw your way through $108 in savings :buttrock. I took my dremel and did the following hackjob. The gauges fit right in ;)

****PICTURE COMING****

In retrospect, I did a shitty job. Another member did it like this, which is probably better and easier. Not that it retains the clips on top which help hold the OBC in place. My way still works, but the OBC is not quite as secure. I saved the tabs I cut off and will put them back in place via superglue. If you want to avoid this, do it his way.

http://i111.photobucket.com/albums/n130/AeroGT3RedWing/alternative.jpg
Now its time to make the gauge panel. I personally lined up the sunglass holder to a piece of cereal box lid and went to town. Afterwards I took a utility knife and cut three slightly bigger than 2 inch holes (I didn't have calipers to measure the exact gauge diameter), and then stuck the gauges in. See photos. When I get the real panel made (September?), I'll update this. If people want, I'll look into making a few and selling them for cheap. Though if I have to become a supporting vendor or something, forget it, as I'd be doing it as a favor rather than a business thing. With the gauge panel made, I set the gauges in place and clamped them into the panel using the threaded clamp provided by VDO. The spin-lock thing is really good and holds the gauges in place perfectly.

Now we turn towards the electrical part - the wiring. I am not an electrical guy by any means, but this part was just as easy as all the cutting and stuff. Below is a picture of the back of one gauge. There are 5 male connectors, labeled 1 through 5. Here's what they are:

1.) Ground for lighting (could actually be either 1 or 2)
2.) 12V power for lighting/dimming (could actually be either 2 or 1)
3.) Ground for gauge (-)
4.) 12V power for gauge (+)
5.) Sending unit (S)

http://i111.photobucket.com/albums/n130/AeroGT3RedWing/backofgauge.jpg

For the gauge ground, port (3), 14 gauge wire MUST BE USED!! A proper ground is essential for accurate reading, so USE 14 GAUGE WIRE! For the lighting, wire gauge is not critical, so for ports (1) and (2), I used 14 gauge since it's what I had the most left over. You could use 16 gauge and the gauges will light up just fine. For the 12V gauge power, port (4), I use 16 gauge as specified by VDO. Whether or not you could use 14 gauge is unknown to me, but since VDO recommends 16, I used 16. I used 16 gauge wire to go from the sendin units to the gauge as well - port(5). Wiring color is up to you, but I suggest brown for ground, red for power, yellow or orange for illumination, as these are what BMW uses. You can use whatever color suits you; you'll find I didn't follow my own recommendations at all except for the ground.

To do the wiring, you simple strip the wire on one end, and insert that open end into the female connector. I took a gauge in with me to Kragen when I bought the connectors to make sure they fit, and bought connectors for 14/16 gauge wire. they sell them for all different wire thickness. I wired the lighting ground and lighting power in parallel (see picture). Though you could run individual wires to individual lighting and ground sources, it is unecessary and will only make for more clutter. To run wires in parallel, just run one wire from the first gauge to the second, one from the second to the third, and one from the third to the source/ground. Make sure the 1-2 and 2-3 and 3-ground/source wires make good contact with each other and the female connector - you want the incoming power to go to the current light AND the next one down the line! Make sure everything is securely fastened with tape/solder/whatever. You do not want anything coming apart under hard driving ;)

http://i111.photobucket.com/albums/n130/AeroGT3RedWing/singleharness.jpg

The picture below shows an almost finished harness installed on two of three gauges.

http://i111.photobucket.com/albums/n130/AeroGT3RedWing/harnessongauge.jpg

You want the wire going to source/ground long enough (duh) to reach its source or ground. I have an aftermarket CD player that doesn't work with the interior dim switch for some reason - it will only light up at 100%. Even with the correct illumination wires plugged in, it still won't work, so I decided to use that dimming wire to go to the gauges. The cigarette lighter is another source of illumination, and will work with the dimmer. At this point you do not actually want to plug in to your power/ground source; I am just dicussing where you will want to when the wiring is finished.

Next is the wiring for the gauge ground and power. You want to make a similar harness for the gauge's 12V power as you did for the lighting, but use 16 gauge wire as VDO recommends. I would do it in parallel to save clutter. I used the power from my CD player. Some say this is bad and will introduce noise into the sound system. They may be right, but my sound system is shitty, I don't plan on upgrading it, and no noise was introduced. It performs as it did before the gauge install. However, if you want to use something else, the anti-stereo people recommend the glove box light. Whatever you do, you want to take power from a "switched" accesory. A switched power line is one that has no power when the keys are not in the ignition. Why? Because the gauges will drain power when the car is not on. The radio, glovebox light, cigarette lighter (depending on year/model) are all examples of switched power. Hooking the gauge power up to the battery terminals would NOT be switched power. Anyways, do the harness as before and make the last wire long enough to reach your source with some slack in the line (duh.)

For the ground, VDO recommends three dedicated grounds. I disregarded this and figured I could get decent ground in parallel, so I made the harness the same as the one for the lighting ground. It worked, and the gauges read accurately. Whether or not you do one ground in parallel or three dedicated ones is up to you. With the harnesses done for both terminals (1) through (4), the only thing remaining was the sending units.

At this point, I went ahead and installed the gauges, plugged in the power and lighting wires, and grounded everything. I ran all my grounds to the aluminum or steel tab sitting behind center console, shown in the picture below. Make sure your ground is good and will not deteriorate/fall off! Use lots of tap and solder if needed. I left plenty of slack in the wire such that I could install the gauges but have them sitting outside of the console for troubleshooting. (See picture below.) I highly recommend this. At this point, with everything wired up but the senders, go ahead and put the key into the accesory on position and turn on the lights. The gauges should light up, and the oil pressure should be all the way to the right, and the temp sensors all the way to the left. Test the dimmer switch to confirm that the gauges dim with the rest of the accesories. This means all your connections thus far should be good.

****PICTURE COMING****

Now lets run the wires to the engine bay. First, we remove the glove box. This is done by removing the 4 screws shown below (red arrows), along with two screws underneath (blue arrows).

http://i111.photobucket.com/albums/n130/AeroGT3RedWing/gloveboxscrews.jpg

Slide the glove box out and put it aside, and remove the plastic cover piece underneath. Things shoud look like this.

http://i111.photobucket.com/albums/n130/AeroGT3RedWing/gloveboxremoved.jpg

Pry back the carpet at the back and you will see a small rubber grommet (blue arrow). This is where the wires will pass through (mine are already in) and is the easier way to get into the engine bay (IMO.) The picture below should the grommet as seen from the passenger cabin and the engine bay.

http://i111.photobucket.com/albums/n130/AeroGT3RedWing/grommet.jpg http://i111.photobucket.com/albums/n130/AeroGT3RedWing/grommetfromengine.jpg

How you want to route the wires through the engine bay is up to you, and depends on where you'r going (ODB, oil center, thermostat, cylinder head, etc) So cut wires (two, three, however many you need) long enough to snake through your engine bay, the grommet, behind the glovebox, and through the center console. Once you've done that, it's time take them through the grommet. Wrap one wire around a pair of scissors as shown in the photo. (see picsture) Then jam the scissors throught the grommet from the passenger side.

http://i111.photobucket.com/albums/n130/AeroGT3RedWing/scissors.jpg

Then go to the engine bay side, unwrap the wire off of the scissor, and pull it through the engine bay. If you are going to have the senders ready, just leave the wire hanging. If you're like me and hadn't gotten them yet, Coil them up somewhere out of the way and leave them be until later. Repeat as necessary, and pull the wires through the grommet. Once finished, route the wires through the center console by going behind this panel:

http://i111.photobucket.com/albums/n130/AeroGT3RedWing/routewires.jpg

Pull the wires out through the center console, strip the ends, attach the female connectors, and plug them into the gauges. Now the gauges are fully wired. Go ahead and put the gauge panel assembly back into the console securey, followed by the OBC. The electrical part is done and you are almost totally finished!

****PICTURE COMING****

If you have an ODB, I don't know what you do to install it. I've heard it's a PITA with the leaking, etc. If you have the oil center, take a 13mm socket and unbolt the oil filter housing cap. Remove the oil center plugs with a allen key, and screw in the sending units (15 ft-lbs MAX as specified by VDO). Then replace the filter housing cap with the oil center, and bolt it in with the same 13mm bolt. The torque spec (25 Nm) is written on the oil center. Attach the wires to the sending unit, and you are done! Oil center FTW :buttrock You're oil pressure and temperature gauges should be fully operational.

****PICTURE COMING****
****PICTURE COMING****

Now it's time for the last gauge. If you did vaccuum pressure, fuel pressure, voltmeter, whatever, then this DIY is not going to help as I didn't install those. If you did water temperature, read on. I am tapping the thermostat housing, so if you are removing the head and tapping the head, go away. Though if you can remove the head yourself, you are way too 1337 to be reading this anyways. There are many DIY's on removing the thermostat housing, so I will summarize:

Remove the fan, disconnect the radiator hoses, unbolt the thermostat housing, take it out :)

Once you have it out, you will want to tap the thermostat. There are (duh) two sides of the thermostat, one going into the block, one going out. You want to tap water coming out. Why? Because this is what's dangerous. Water coming out at 300 Fahrenheit is water that has boiled and isn't cooling your engine. But water coming in at 120 degrees could still be going into an overheating engine, so it's inconsequential to know the temp at this location in the system. This is why you want to tap the outgoing line. Technically if the T-stat gets stuck shut you're SOL as your gauge will read nothing while your engine fries, but usually t-stats fail in the open position. But if you were really hardcore you'de tap the block or the cylinder head to get around this. I am not hardcore by any means. The outgoing line is usually the upper radiator hose, and will say "Zum Kuhler" (to the radiator), but I don't know if this is how it is on the M50/52 or S50/52. On the M42, it's the upper radiator hose. Check to be sure.

The tap you want is 1/8-27 NPT (national pipe thread.) Shop tools inc. in Palo Alto, CA sells it for $20, Napa auto parts had it for $17. Mine will be for sale in September, when a friend is done using it. The drill bit size is 11/32". Why you use a 11/32 drill bit on 1/8" tap is beyond me; but the tap is way bigger than 1/8" so 11/32nd's is indeed correct. Now you drill the hole. If you have a weak ass drill like me, start with smaller drill bit sizes and work your way up to the big boys. Here is an important tip on where to drill/tap:

The expertly drawn MSpaint pic below shows a good place to tap, and a bad place to tap. The blue is the shaft of the sending unit, and the green is the hex nut that is welded to it. On the M42, you could end up with either of the two thermostat housing cross sections, A or B. You want to drill on the outside of a round part, like in section A. This will allow you to fully screw the sender in and get a good seal. If you do at in part B, the green hex nut will run into the surrounding area and prevent it from touching the outside of the hole you drilled, preventing a good seal and possibly allowing a leak!

http://i111.photobucket.com/albums/n130/AeroGT3RedWing/taplocation.gif

The tap is threaded like a screw but the threads get progressively deeper. To tap the hole, simply insert the tap into it and start to turn the tap clockwise. When you hit resistance, back the tap out, clean it off, and clean out the threads you have cut. I have cutting oil on me, but if you don't WD-40 should work fine. SOAK the tap and the hole with lubricant each time you back the tap out for cleaning. Continue to repeat this process until the tap has passed all the way through the housing and the sending unit scrwes in without to much effort. Once you have correctly tapped the thermostat housing, clean the housing thouroughly to rid it of any cutting oil. Finally, thread the sending unit (very tightly) into the housing. If you are concerned about leaks, cut some washers (2 or more) out of teflon tape and place them on the sending unit before scrweing it in. If you tap the thermostat in the right location as shown in the picture and tap the hole properly, you should not have a problem with leaks. Now you put the t-stat housing back and bleed the system. I recommend jacking the front end up as it will usually self bleed if you do so before refilling. Once done with that, strip the end of the sending unit wire and fasten it securaly to the knob on the sending unit. BAM! You are done! Get back in the car and clean up, then go for a drive to test it all out!

http://i111.photobucket.com/albums/n130/AeroGT3RedWing/finalresultday.jpg

http://i111.photobucket.com/albums/n130/AeroGT3RedWing/finalresultnight.jpg

The pressure should be 60+ Psi at cold idle, and 60+ during driving. Once the oil is warm (200 degrees), you should read 15-20 Psi at idle and 60+ driving. It should take 10+ minutes for oil to get to 200 degrees in ~70 degree weather. Water temp should be around 200 as well after 10 minutes of driving. I am going to just pull off my fan and see watertemps do. The oil temp is useful as I now know when it's "safe" to go WOT (oil = 200 degrees or higher).

I tried to make this DIY as thourough and as simple as possible. If I forgot something, you have corrections, or suggestions, just post up in this thread. If you want more pictures of something, just ask and I'll have a friend who is doing the same install soon take them for you. You can PM me or whatever, and feel free to email me if you can't view the pictures and I will email them to you. Cheers and good luck!