I Write of Olaf

October 21st, 2011 by Harrumpher Leave a reply »

odocog1The size of Lincoln’s head on a one-cent coin, the demon cog caused trouble. I just had to go for a long, vigorous walk to relieve my electro-mechanical agita. Now my aged Volvo’s odometer works though.

I don’t hold any personal grudge against this wee hard-plastic toothed wheel. It is just as the cliché goes a cog. It also represents a small design flaw for what allegedly is a sturdy, well-built car, a 1996 850 sedan.

When the odo stopped working, I looked in a manual and snooped online. Sure enough, the 850 series is infamous for having this problem around 100,000 miles. Olaf, as we call the platinum silver car, had over 135k when it stopped visibly recording mileage. Allegedly the ECU (engine control unit) computer continued to track distance, but I couldn’t see any advance nor use the trip function.

The design flaw is worse than just putting a brittle and weak part as a single point of failure for a commonly used feature. Volvo engineering ensured that repairing it would tax mechanics as well as we cheap frugal owners. I asked a Volvo dealer about it and he said it happens to all 850s and they could fix it for about $250.

Harrumph, as I am known to say.

The tiny part is unique to the internals of the odometer. There are no substitute. It sells for $15. The rest of the cost is labor.

Why, might you ask, would they charge you two hours of mechanic’s time for something so simple? You’ll hear that it’s not simple. I saw the instructions and ordered the demon wheel, determined to do this myself, no matter how terrified I would be of screwing up the instrument panel and odo, requiring then much more mechanic’s time to undo it all and do it right.

One of the online tutorials for the process is here. There are more detailed ones, but this covers the gist and shows why it’s a big deal for something so simple as replacing a defective cog wheel with a good one. At its basics:

  • Have or acquire a variety of Torx wrenches or bits. (Three key screws holding the odo in place take an almost impossible to find T8; five auto stores including two foreign specialists didn’t have any.)
  • Disconnect battery (to avoid Check Engine error and a trip to a mechanic to turn that off when you finish).
  • Pry out four AC vents.
  • Open one door-side vent with screw, partially remove that, pry and pull forward this vent.
  • Remove seven screws in vent openings and under instrument overhang.
  • Make as much space as possible by moving driver seat back and steering wheel and column down and back. You’ll need ever inch.
  • Carefully wiggle and pry cover over instrument panel, and to its left and right. Force it as high as you can without breaking it.
  • Wriggle and force up the and out the two electrical connectors to the back of the instrument panel.
  • Open the two clips holding the panel to the body.
  • Place a protective towel on the area in front of the panel. (To keep from scratching or scratching the panel lens in the battle to follow.)
  • Grunt, sweat, swear, pry and use all available hands and likely your forehead to make enough space to sneak the instrument panel out of the too narrow area holding it in. (Volvo forums on this often have colorful descriptions of the near impossibility of this operation.)
  • Congratulate yourself and remove the panel to a bench or table for the repair.
  • Remove maybe 10 (depending on whether you have the German or Japanese panel) screws.
  • Flip the panel, carefully pry the two major sections apart, careful not to crack anything or strip the panel covering or hurt the gauge dials. Then set the front part aside so its many component leads are safe.
  • Take the half with the odo, flip it over, and remove the three screws holding the odo unit in place through its circuit board. This requires that mythical T8. I ended up using a tiny, but sturdy flat-blade screw driver, holding it with a sturdy cloth napkin and breaking into a sweat removing and later tightening the damnably snug screws.
  • Slowly pull out the odo motor and display. This is fragile and its leads require considerable care.
  • Remove the two screws holding the odo motor.
  • Pry off the plastic fitting and gear to open the compartment with the likely broken wheel.
  • Pluck out the bad gear, remove the broken tooth or teeth, put a spot of petrolatum as a lube on the larger wheel, and put your $15 tiny treasure in its place.
  • From there, it’s reversing everything, making sure at each step that the leads and components fit precisely and do not bend or break any parts.

In retrospect, I can see why they charge software-engineer wages to do the job. Plus, certainly if they goof it up anywhere among the many opportunities, that’s their problem and expense to fix.

Volvo blundered in its design on this component as well as in its serviceability. Yet, many years later, I pay the price either in anxiety and effort or in cash.

I’m not at all sure I’ll ever need these skills or this knowledge subset…nor a large set of Torx bits (down to T10, but lacking T8). But, hey, those were on sale and I’m a cheap frugal guy.

While I was doing the panel extraction, I revisited an old awareness though. My knuckles were rubbing, the dash cover was doing its best to crush me and prevent the removal, and I flashed on that tiny wheel I’d replace. Our bodies are a lot like that.

There are so many small components in our innards, brains, torso organs and more, that can malfunction. In a car or human, any of a long list of key parts can fail. Our body repairs or bypasses them often. Sometimes, we get sick and need surgery, medicine or prostheses. In less common cases, we or the car just stop working.

I can’t really fix my body often. So, I was pleased to do my bit for Olaf.

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2 Responses

  1. #1 says:

    For future reference, Micro Center is the correct place to get smallish Torx and other funny-shaped screwdrivers: they come in $10-$20 kits. The big ones I could only find in-person at Home Depot/Lowes/AutoZone, where they were overpriced; online is a good idea for those.

  2. Harrumpher says:

    Now that you write it, that makes perfect sense. I was likely thinking the mechanical in the electro-mechanical. Short the T8, I ended up with a big kit from Auto Zone with lots more bits than Torx on sale for $10. I may look at MC for the teeny weenies.

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