Saturday, May 24, 2008
Fuel System Cleaner
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.
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:
- The coolant drain bolt size is 19mm, and the BMW TIS says the torque is 25 NM (18 ft-lbs)...or the same light torque as the oil drain bolt.
- A box end wrench (SK in this case) will not fit between the tip of the O2 sensor and the face of the bolt because there is only about 3-4 mm of clearance between the two components.
- A straight / standard open-end wrench is a bit unweildy for the work area. I asked Mike Miller of the BMWCCA's "Tech Talk" feature about this process and he suggested I use a stubby wrench. Today I confirmed that while a stubby wrench is not mandatory, it would certainly help.
- I managed to get a standard 19 mm open end wrench on the bolt, but at an uncomfortable angle that might trash the bolt if it doesn't want to come out easily. I may have to buy a crummy 19 mm open end wrench and sacrifice it with my vice to get the exact angle I need. Even then, it will be slow going since there isn't much room to swing a wrench of any kind (stubby or otherwise).
- I don't think the BMW dealer techs (yes, including mine) ever bothered to pull this bolt for a "coolant flush". Frankly, I think they all just drain the radiator, refill with the 50/50 mix and call it a day. At this point I can't say that I blame them, and I may wind up doing it the very same way. Only, if I do, I'll likely switch to an annual coolant flush interval to compensate for leaving a bulk of the old coolant in the block.
- As I took a moment to think while under the car staring at the coolant drain bolt and its juxtaposition to the O2 sensor I think I heard a German engineer laughing manically, but I could be wrong since it occurred at the end of a long day.
More to follow on this procedure when I get around to doing it.
Mileage: 160250, Parts: $8, Parts Saved: $4