Tuesday, November 17, 2015

Fall 2015 Vehicle Safety Report

Around twenty students from this year's Physics: Mechanics and Energy class and one instructor performed vehicle safety inspections on over forty student vehicles Monday. This was the largest number of vehicles ever seen for this activity.

Most vehicles seen were serviceable, although a number were noticeably battered or rusty.

The following particular safety conditions were noted, documented here for the purposes of education and for the record, so we can compare year to year:
  • Three vehicles were very low on engine oil, and required three or four quarts to get them "up to the mark." These engines would have seized had this condition been allowed to continue for very much longer. If your vehicle is using or losing this much oil, it is no longer sufficient to wait for oil changes to add oil. You have to check the dipstick and add oil more frequently. The best thing to do is to check the oil each time you add gas, until you begin to get a better idea of how much oil your vehicle is using. Then, once you really know what is going on, you can put yourself on a less frequent schedule. Don't let your engine oil drop below the minimum mark on the dipstick. And, if you can possibly afford it, get the vehicle repaired. Generally speaking, a vehicle that is losing oil from a leak can be repaired less expensively than one that is using or burning a lot of oil internally and needs an engine rebuild, a replacement engine, or simply to go to the junkyard.
  • Several tires were low in air pressure, below 20 psi. Tires this low are dangerous because the steering is affected. Steering becomes spongy, and the vehicle will wobble noticeably on corners.
  • Some tires were over-inflated, above 40 psi. The correct operating air pressure for the tires is written on a sticker placed inside the driver's door jamb. It is not the pressure written on the sidewall of the tire. That is the tire's maximum pressure, not the vehicle's design operating pressure. Most sedan cars and light trucks use a tire pressure between 30 and 36 psi. Adding more pressure makes the vehicle bounce on bumps, and you can bounce right off the road on a corner, especially on "washboarded" dirt roads.
  • One vehicle had a worn tie rod end or steering box. This is detectable because of thunking noises in the steering mechanism on slow turns such as those used in parking lots. This is an unsafe condition and should be rectified immediately. Tie rod ends when worn will simply fall out, causing a catastrophic lack of steering.
  • Several owners of vehicles with high mileage, over 150,000 miles, had check engine lights on and asked for the trouble codes to be "pulled" and checked, even though they had had them pulled before and had no intention of rectifying the particular problem. In general, this is a good procedure. Even though it's often not cost-effective or sometimes not possible to fix some minor check-engine defects in high mileage cars, and so we might drive with the check engine light permanently on, it's still best to pull the codes periodically, in case a new defect has appeared that is more dangerous.
  • A new difficulty we observed this year for the first time: An older vehicle was found with failing automatic tire pressure sensors. These resulted in tire pressure warning lights coming on, even when the tires were correctly inflated, or at least within the normal tolerance of one or two psi. Either the tire pressure warning sensors should be replaced, or the tire pressures must now be checked more frequently, since there is no other way to tell whether tire pressure is low or not.
This concludes your Fall 2015 vehicle safety report.

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