Design for serviceability
I was driving around with a friend of mine last week and her car started to smell like burnt rubber.First off I have to say that we did no burnouts so the tires were not to blame.Another data point is that after she turned on the air conditioner to defrost the windows the battery light came on. This is also when we smelled rubber the strongest.The car in question for this exercise is a Mini Cooper S.My diagnosis at the spot was that the serpentine belt or the belt tensioner was bad. The second thought from looking under the bonnet (it is a car of English heritage after all) was that I couldn't even touch the belt it was so freaking cramped in the engine compartment.Yesterday the diagnosis came back from the shop with the same assessment.Here's where it's fucked up.To change the belt tensioner you have to essentially remove the engine.I shit you not.The instructions from Pelican go on to say...
At this point, start carefully jacking up the engine. The idea here is to make the belt tensioner accessible from the passenger side of the engine. Once the supercharger pulley is visible as shown in Figure 20, stop jacking. Keep an eye out for any cables or items that may be binding or getting caught. If you encounter this, stop, carefully rectify the problem and move on.
Whiskey. Tango. Foxtrot.I can see something that isn't likely to be replaced to have some odd service instructions. But something as simple as a belt tensioner?!
You'll need to remove the passenger side engine mount from the frame rail in order to access the tensioner bolts.
Huh?If this was a race car where every cubic millimeter (microliter) has to make the car go faster I could see why you would package something like that.For a passenger car on the other hand this is stupid.As an engineer you have to look at your designs and see what are the tradeoffs. Sometimes function dictates form -- a hard to service design. But when the design goes back to dictate bad engineering that's plain wrong.An example of a hard-to-service part is something on my bike. A clutch replacement involves removing the back half of the bike. However there's no other real way to do that since the output shaft from the engine runs longitudinally the only real way of mounting the clutch is behind the engine. And since the transmission is behind that... and so forth... you're left with a design that has a baked-in flaw. It does make other service to the bike super easy though.That is a decision. Some things are easier or parts lighter in exchange for something that is rarely done being hard.But something like a belt tensioner -- something that's likely to need service -- to be that hard? That is a mistake.