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Friday, April 25, 2014

Doug's Domain

Doug Vetter, ATP/CFI

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Sunday, May 4, 2008

Aux Cooling Fan Replacement

(Image: New E36 Electric Auxiliary Fan Installed) As expected the aux fan arrived from Koala Motorsport this week. I was so busy this weekend with more pressing regular life matters I almost didn't get the time to install the part, but I managed to get the other work done ahead of time and install the new fan.

While the BMW TIS suggests you need to remove the bumper cover to remove the fan and frame assembly, that is incorrect. I just removed a few protective panels attached to the bottom of the bumper cover and six screws on the fan assembly itself and the fan assembly slid right out the bottom of the car.

I stopped by the dealer earlier this week to get a quote on the work. It turned out that if I knew nothing about my car and just walked into the dealer to get this done my wallet would be lighter by a whopping $805 rather than the $250 it cost me to buy an aftermarket part and do the job myself. Unlike most jobs where labor dominates the cost the vast majority of this repair is sunk in the cost of the part, which is a staggering $642. That's just crazy. I see no reason to buy the OE part when the aftermarket part looks and appears to function identically to it.

I took apart the old fan to figure out what failed. The rotor (rotating assembly) of the electric motor was in good shape, but the permanent magnets that surrounded the rotor were broken in several places. Moving the rotor back and forth caused the magnet fragments to move around and bunch up with each other. This caused a lot of friction in the rotating assembly and frankly I'm surprised the motor actually worked in this condition. Hello, garbage man? I have a ten year old aux fan for ya...

Now for the fun part - cost analysis. Retail price for the OE fan is $642. I paid $240 and change + shipping, or $252 total. This is a savings of almost $400. The quote at the dealer for this job was $805. $805 - $642 = $163 in labor I saved by doing this job myself. The total savings is obviously $805 - $252 or $553. Not a bad payday for a few hours of research and wrenching, don't you think? DIY. It's the thing to do. Seriously.

Mileage: 159633, Parts: $252, Parts Saved: $390, Labor Saved: $163

Saturday, May 17, 2008

Oil Service, Fuel Filter

This week the car passed 160K miles and that prompted a check of my maintenance schedule. That revealed the need for an oil service, a fuel filter change, and a coolant flush. I knew the oil service would be easy enough, but the fuel filter and coolant flush would be firsts for me as DIY procedures.

(Image: Date in service written on fuel filter)After doing some research on the usual forums I realized that replacing the fuel filter would be a relatively simple process but I decided to wait on the coolant flush until I had received a clarification of one aspect of the procedure from a few other sources before tackling it. Better safe than sorry, especially when a $150 oxygen sensor is involved. Long story. I'll explain it when the time comes.

I expect to detail the fuel filter process in a DIY soon so I won't go into detail here but I will tell you that the way gasoline eats through polyisocyanurate insulation panels (you know, the stuff they put under residential siding and the very same panels I use to line the gravel driveway when I work outside under my car) is kind of cool. What's not cool is how the chemical reaction creates an evil goo that remains in molten form just long enough to find it's way into an unsuspecting DIY technician's hair.

Further, I learned that it is really hard to get the goo out of said technician's hair after the gasoline evaporates and the foam resolidifies unless one uses a solvent like, oh, say, gasoline applied to a blue shop towel to remove it. To borrow an old shampoo marketing slogan, "Gee, your hair smells like gasoline and polyisocyanurate foam". Oh well. If I get cancer, at least I'll know why. :-|

The labor rate at my dealer is now $110/hour so the labor savings from DIY oil services has risen as well. I now save about $90 in labor and $10 in parts doing this myself. The oil ran about $50 and the oil analysis remains about $20, so the basic cost for a DIY oil service and analysis at this point is $70 in parts.

The fuel filter was $30 and the labor to replace it at the dealer is $70. As usual the 7% sales tax largely offset the 10% CCA discount on the parts, so I saved $70 doing this myself.

Mileage: 160180, Parts: $100, Parts Saved: $10, Labor Saved: $160

Saturday, May 24, 2008

Fuel System Cleaner

(Image: Fuel filter cut open for inspection)As I mentioned in a prior blog entry BMW recently switched its recommended fuel system cleaner. I was told it had something to do with the change to ethanol based fuels but I don't know if that's true. What I do know is that the old stuff used to come in a small white translucent bottle like that depicted in my Fuel Pump DIY article and cost about $4. The new stuff comes in an opaque black bottle that looks suspiciously (read: exactly) like the one used for Techron sold in the aftermarket and costs $12.

I have long known that Techron sells for about $8 a bottle in the aftermarket so I felt I was getting a good deal buying BMW's fuel system cleaner for $4. Since that product is no longer available and I really didn't want to pay 50% more for what is very likely Techron relabled for BMW I decided to buy a bottle of Techron while at my local auto supply and drop it in the tank this week.

I still haven't figured out whether it makes sense to pay even $8 for what is largely Stoddard Solvent (a.k.a. mineral spirits, paint thinner, etc.), naphtha, and some xylene and benzene mixed in along with an almost insignificant amount of the proprietary detergent called Techron, but I suppose I'll figure it out when I have my fuel injectors flow balanced or pull the head off the engine.

This rebranding thing isn't new, incidentally. Auto manufacturers are in the business of building cars...not chemical engineering. What's new is that manufacturers aren't even bothering to rebrand certain parts. Case in point: while I was at the parts window I saw one of the techs fulfilling an order for the special 10W-60 oil required by the S54-equipped M3 and the only reference to BMW on the bottle was the part number in small letters on the back. The label looked like any other label you'd find on a bottle of Castrol sold in the aftermarket. The difference here being, of course, that you can't get this specific oil anywhere but a BMW dealer due to exclusivity agreements between Castrol and BMW.

Fuel Filter Inspection

Last week I set the fuel filter aside to drain and dry out because I knew I wanted to eventually cut it open to inspect the element. Today I used a metal bandsaw to cut off the ends of the filter and was pleasantly surprised to find the paper element completely clean and in one piece.

In fact it was so clean that if I knew for sure that the recommended replacement interval of 36K miles as specified in the TIS was based strictly on some statistical estimate of expected contamination I would gladly extend the interval to something more reasonable like 54K or 72K miles. However, since BMW tends to advocate less than proper maintenance these days I have to believe that the interval is based more on the integrity of the filter medium. For this reason and because the filters are relatively inexpensive and easy to replace I'll likely continue to use the 36K interval.

Oil Analysis

My last oil analysis showed up this week as well and fortunately there's nothing to report. Aside from the tester's comments it looked like a copy of the last analysis...which is exactly what I want to see. All of the wear metals are significantly below the statistical averages and no coolant or other contaminants were found. So the M52 appears to be holding up well passing 160K.

Coolant Flush Research

I've been trying to figure out how to (easily) do a coolant flush involving the block drain without removing the pre-cat O2 sensor that gets in the way of using a box wrench, so today I jacked up the front end to do some experimentation and figured out a few things:

More to follow on this procedure when I get around to doing it.

Mileage: 160250, Parts: $8, Parts Saved: $4

Saturday, May 31, 2008

Aux Fan Revisited

Yesterday while running a few errands during lunch I decided to use the air conditioning for the first time this season. Since I knew I had just repaired the aux fan I decided to flick the snowflake button on and walk out in front of the car to make sure the fan was working. To my surprise I found it at a dead stop. Since turning on the air conditioning turns on the aux fan I knew this was a problem, and sure enough I also found the compressor making noise indicative of higher than normal pressure in the system. I turned off the air conditioning to reduce stress on the compressor and pondered the cause while I went about my business and carefully watched the temperature gauge.

While doing the aux fan replacement I noticed the electrical plug fit tightly into the receptacle and required a lot of force to press together. In fact, I had to use a channel-lox pliers to press them together sufficiently for the plastic spring clips to grab properly. I was acutely aware at the time that the connectors might separate so I put a ty-wrap around the spring clips to lock the assembly in place. My first instinct in the troubleshooting process was that this connection had come apart.

Unfortunately, once I got home, put the car up ramps and managed to remove the panels I found the electrical plug in exactly the same condition I'd left it. The first troubleshooting step was to pull the plug to test for power with the engine running and the air conditioning turned on. Under these conditions I found 14 volts DC on one of the terminals (the low-speed side). This meant that the low speed fan relay and the associated fuse were in good shape, so the problem lay with either the fan motor or the electrical plug / receptacle assembly. I turned off the engine to reconnect the plug and then started the engine again to retest it. Thankfully, the fan turned on as expected, which eliminated the fan as the culprit. This little revelation caused me to breathe a sigh of relief because I'd just saved myself from the hassle of cross shipping the fan with a new unit.

Concerned that the poor connection might be due to oxidation on the older contacts of the plug I went over to my brother's electrical van to pull out out a tube of anti-oxidation paste (a conductive dark gray goo that we use whenever mating dissimilar metals like copper and aluminum to prevent corrosion). I used one of my picks (the same ones I use to remove snap rings or the o-ring on the oil filter cannister) to put a very small amount into each female conductor terminal located in the electrical plug. I inserted the connector into the receptacle several times before seating it for good and put a ty-wrap around the spring clips to lock it in place. I tested the fan one last time before I reinstalled the protective panels and called it a day.

I expect to replace this connector assembly with a new waterproof unit but that will have to wait until my schedule permits finding an appropriate part. The only thing that may make it difficult to find is the fact that it must support a minimum of 20 Amps DC continuous running load.

If I had brought this to the dealer they would have charged me a diagnostic charge of around $100 plus the labor to actually fix it, which could have been another hour, or $110. The total process, including searching for the anti-oxidation paste took me about 45 minutes, so I'll just conservatively call it $100 labor saved.

Mileage: 160680; Labor Saved: $100