Monday, May 29, 2017

mini love - part 11

It appears that I finally have all the parts to begin the gauge installation in earnests.

I am entertaining getting a Inovate Wideband Meter to monitor the air/fuel ratio

I thought I need two orange bulbs for the new gauges to match the orange color lighting of the Mini factory gauges; great Walmart has this for just $2.73 a pack

I first went to Napa to try finding the 1/8" compression x 1/8" FIP street elbow fitting. I tried finding one on Amazon to little luck. After spending a lot of time I did find one but I did not want to wait for shipping. My local Napa has a good assortment of brass fluid fittings. The problem when I eventually found the right bin that should contain them, it was empty. Next I try Home Depot and I was not optimistic.

to my wildest surprise Home Depot does carry it

problem is the only bag they have has a wrong item in it - I then headed off to another Home Depot after have the staff checking stock

being the Memorial holiday weekend Home Depot parking is a zoo and Mini knows better to avoid it like a plague so we found a shade from the sun; we came home with the fitting

Walmart wants a ransom for the orange bulbs so I voted with my feet to get them from Amazon

While a bit of the threads of the pressure inlet fitting has been rounded off from someone crossed threaded with an incompatible fitting I decided that I can make it work instead of return the gauge and buy another one. I perform a function test on the gauge before proceeding to cut off the two brass studs that I don't need.

cutting off the two brass mounting studs with a abrasive cutting disc

next I ground the cut flush to the plastic housing leaving no sharp edge

install the street elbow so the pressure line entry would be 90-degree

I managed to restore enough threads to achieve a good fit

next is to make a tee harness for the gauge lights

now the tee harness is ready to be spliced into the stereo head unit's illumination and ground wires; the illumination signal is the same as the instrument light which can be dimmed

The 1/8" compression to 1/8" FIP street elbow from Home Depot projects much farther than the one that shipped with the Auto Meter metal gauge pod. This imposes significant problem for mounting the oil pressure gauge to the right hand side of the Tachometer as the dash curves farther out towards the center of the car, leaving even less room to accommodate the brass fitting between the gauge and the dash - and all these have to comprehend the height adjustment arc of the steering wheel. They didn't name the car Mini for no reason.

To make all these work I swapped the left right positions of the boost gauge and the oil pressure gauge as the boost gauge with the unadulterated pipe thread allows the compact street elbow to project less than the same with the oil pressure gauge with the lightly compromised threads.

I added a second 1/8" nylon pressure line for the oil pressure gauge. I also made up a Y harness for the two gauge illuminate bulbs to be spliced into the audio head unit harness's illumination signal. Next is to remove the factory oil pressure switch and add the breakout adapter to accommodate the 1/8" brass compression fitting for the oil pressure gauge's nylon pressure line. I would soon regret that I didn't take the opportunity when I have the engine out to do this. The need to use a 27mm deep socket and the downward till of the oil pressure switch leaving no room to swing even a 3/8" rachet wrench, and even if there is it is so low in a very awkward location that one is challenge to exert the force needed to break loose the oil pressure switch. I felt defeated and wonder should I just take the car to a Mini specialist. By now the sun is overhead and begins to get uncomfortable to work. Time for a nap.

The Tritec engine that powers the first generation Mini Coopers was a joint venture development between BMW and Chrysler - that's right; unimaginable. The engine has proven to be extremely robust and close to indestructible even heavy modification to more than double of the Cooper S boosted induction high output. The base engine have been used in different varient in Neon and PT Cruiser, in addition to the first generation of BMW's modern Mini Coopers.

For some first hand history on the engine development here are three forum posts that are of great interest.
Tritec Engine Developer here
In the beginning - The origins of the Tritec Engine
The Tritec engine Part 2 - Early design efforts and building the team

Part 3 of the series has not been written but the author promised will be soon. I read with fascination and interest as rarely development history like this is rarely told nowadays. There are a few links in the posts are also great read for any piston heads.

Installing two all mechanical gauges would proved to be a lot of challenge, especially using the low cost Alta gauge pods. The brass fittings behind the gauges requires additional depth which the Mini is in short supply.

The street elbow that I bought at Home Depot (right) is not as compact as the one that came with the Auto Meter metal gauge cup (left)

As I sensed the possible defeat I realized I can gain a few millimeters of clearance by rounding off the shape edges and corners of the street elbow fittings

Grinding down the two brass street elbows I immediately notice the one from Home Depot is significantly harder than the one from Auto Meter. The former is rock hard because the manufacturer skimmed on the copper content. Race to the bottom is so widespread today. Both my Auto Meter gauges are made in USA, though I am sure with a lot of Asian contents.

a lot of grinding and they are done; note that the oil pressure gauge's fitting protrudes father out of the back because of the lesser street elbow and the compromised threads on the gauge

Nothing is easy with the Mini. As I tried to remove the oil pressure switch I would regret that I didn't at lease loosen it when I have the engine out. There is simply no space to accommodate a wrench and with the deep 27mm socket one have to reach in and down behind the engine to try to exert enought force to loosen the pressure switch. Fortunately I remember I have this pivot heat 3/8" ratchet wrench that I totally forgotten that I own. This is the only tool in my possession that make the removal possible.

One question that I had for myself is can I use teflon tape to install the oil pressure breakout fittings as well as to reinstall the oil pressure switch. Teflon tape is non-conductive and on the surface it seems I would be safer to go to auto parts store and buy a tube of thread compound that are designed to withstand engine oil. This concern is the oil pressure switch relies on the metal case to make contact with the fitting, and the engine block to complete the electric circuit for it to work. I however reasoned that teflon tape should be just fine. While telflon is non conductive when you tighten the fitting the metal threads cut through the tape at many places and there should be plenty of conductivity for a low current switch. I save the money and a trip to the auto parts store.

I took a good photo of the oil pressure switch for future reference

the silver fitting is has a 1/8" female NPT port that I would use for the 1/8" line's compression fitting

this is compression fitting for the oil pressure gauge line to be connected to the new breakout fitting

here you can see the 1/8" NPT port of the breakout fitting

with the fitting the oil pressure switch sits father away and the wire and connector is barely long enough to reach it; I added a cable tie to release the stress on the single conductor wire branch; here you can see the 1/8" nylon line and the compression fitting (it is rated for 250 PSI)

I use cable ties to secure the nylon line and protect it from chafing damage

One of the reasons that I chose the mechanical oil pressure gauge is to avoid the complexity of remote-mounting the pressure transducer like this blog post. I also distrust the reliability of aftermarket oil pressure transducers and want to keep the cost down without compromising on the end result.

remote mounting a oil pressure transducer

test fitting and check for adequate clearance at the back of the gauges

the backlights are simply spliced into the audio head unit's Illumination signal

I am very unimpressed with these low cost Alta gauge pods. They are poorly designed and put too much stress onto the tachometer. Structurally the unsupported cantilever pods cannot support even light weight electric or electronic gauges, let alone deep and heavy mechanical gauges that I chose to use. Instead of buying a more expensive gauge pod (circa $200 - $250) I would fix the Alta's defects.

the idea is to fix what Alta's major design defect - the gauge pods will succumb to gravity and sag

my idea is to fabricate a compact bracket to support the lever arms of the two gauge pods; this piece of extruded aluminum is just perfect once I am done

I just estimate the length that is needed to support the arms of the two pods

next measure the center to center of the two holes and the hole diameter

the aluminium bracket is thin enough not to fit within the gap between the pod arms and the tachometer housing

since I have to create a small bend I thought it would be easier if I take out some material on the bracket; don't mock me for how rough this look for it is not the final product

divide and conquer

I reshape the bracket to a slight curvature to conform to the curved surface of the tachometer backside

the aluminum bracket releases the stresses one would otherwise impose on the two screws and the plastic screw posts inside the tachometer which were never designed for this duty

as no one is going to see the back side of the gauges I didn't bother to make the bracket too pretty

test fitting the gauges and check against potential interference against the dashboard at the back; then making the final connections for the nylon lines to the gauges as well as the wiring for the backlights

it is quite unnerving to bring a pressurized oil line into the cabin; I triple checked that the compression fittings are proper installed and tighten, but no over-tighten; you can see the segment of engine oil the in nylon line going into the cockpit

With the mechanical oil pressure switch installation a failure is not an option. If I were to improperly installed or tighten the compression fittings for the nylon line disaster is immediate and the aftermath is very messy.

all is good and I went for a test drive; I am more in love with and appreciate this little car than ever

the R53 is now approaching 20 years from the date the first generation modern Mini's were designed and styled; it withstood the test of time remarkably well and it is one of the best looking cars in recent history

one big challenge in this project is to be able to retain the base trim of the factory tachometer and not having to cut into ro punch holes into the rubber gasket that hides the wire loom; I accomplished both

There are a few things that I like about these Auto Meter gauges. They are clean looking and both has a full sweep meter movement because of their mechanical constructions. The graduations and numbers are very legible. All the numbers are upright (I know, the factory gauges are radial but they are much larger). It is important to match the gauge with the operating range so I chose the 100 PSI gauge instead of 150 PSI oil pressure gauge. When cold after starting the oil pressure register as high as 65 PSI here in the mild Pacific Northwest. I would expect it can hit near 100 PSI in Minnesota winter though the gauge would not be damaged even if you exceed the maximum slightly.

While it makes little difference these gauges sports Made in USA on the dial. The hardware and fittings that come with the gauges are top quality as they were decades ago. The Auto Meter Ultra Lite series are nice gauges at affordable prices even compared to a lot of no-name brands.

all that are included with the mechanical oil pressure gauge

I am thrilled and so is the Mini

When I ordered my Mini in 2004 I also ordered many factory DIY add-on accessory kits. These includes all clear rear lights, front fog lights, rear fog light, security alarm, car cover, and a set of all black Aero Grills. Of these I am still not convinced the Aero Grills will work for the pepper white body color with strong chrome ascent that my Mini has. Why not just put them on and see how they look?

A while ago I actually try to do just that. I first try to save some work by holding up the upper grill against the Mini to see what it would look but that was dissatisfactory. To do that I cannot see the whole front end. I decided to prop it against the existing grill but it just won't stay there due to the slopped ledge of the bumper cover. I tied it to the existing grill with a piece of wire so I could step back and see how it would look. I feel that it looks out of place with my white and chrome theme. While I actually tried to swap the upper grill to get the actual appearance that turned out not something feasible.

I tried to remove the sheet metal nuts for the existing grill but I could see that doing so will risk breaking the plastic studs of the grill. So I could not just put on the Areo grills and return to the factory grills if I don't like how they look.

I think the all black Areo grill looks out of place with my Mini white and chrome theme

I am quite happy with the existing understated appearance

Fortunately for me Walmart wants too much for the orange bulbs that I thought I would need to swap out the plain ones that came with the Auto Meter gauges. We have a tendency to get ahead of ourselves some times especially planning the logistics for a project. The gauges came with a red and a green filter. I immediately assume the red filter will result in a red light for the gauge's dial face. Not so. The color is amber, and as close to the Mini's gauges as I can expect. This is because the low wattage (sub 3.8 W) incandescent bulb already has a very warm spectrum and with a red filter the result is an amber color light.


  1. Long story short, I used teflon on a Volvo pressure sender and a little thread got jammed in the tiny opening and showed I had zero oil pressure. I had to ignore it and drive to get to where I was going. Code on with natural gas is to leave the first 2 threads bare with no tape to avoid bits of teflon tape being shed.

  2. Just to be absolutely that my assessment is correct, I first rationalize that the factory oil pressure switch has to be normally closed when things are kosher, I broke out my Harbor Freight $2.99 DMM to conduct a sanity check. I measured the resistance between the stock oil pressure switch sender and the Mini chassis and the resistance in in the order of a few OHMs. Good enough for me and Mini and I are happy. Teflon tape is just fine.