Rear-Axle Woes
Q:When my 2000 Ford Ranger recently had all its fluids replaced, the mechanic found metal shavings in the rear differential. He suspects some wear and tear and says if I keep driving the truck as is, the axle will lock up. Is that possible? The truck has 68,000 miles. He said it probably happened because I carry my motorcycle in it, but that only weighs about 550 pounds. I don't put the motorcycle in the bed of the truck anymore. He estimated the repair might cost between $350 and $700. Would it be better to get a differential at the scrap yard?
A:Of all the 2000 model-year Rangers, 1540 pounds is the lowest maximum payload rating. That eliminates carrying your motorcycle as the cause of anything. Many rear-axle assemblies have a magnet mounted to the differential cover. This magnet attracts fine metal shavings caused by normal wear and should be thoroughly cleaned during a routine service. If that's what the technician was pointing to as the reason to replace the differential, don't do it. Typically, any abnormal wear in a differential assembly will cause a substantial noise (gear whine at various speeds, growling noise caused by damaged bearings, or a clunking sound from worn or loose parts). If none of these symptoms exists and only normal metal shavings were found, get a new technician and move on. Yes, a rear axle locking up can be dangerous, but the majority of the time, you'll be well aware of the problem long before it reaches that point.
Jumpy Ford Gauges
Q:I have a 1994 Ford Ranger with 87,000 miles. When driving, the battery-gauge needle jumps. What does this mean?
A:Typically, a failure within the charging system will display a steady decrease in battery voltage at the gauge. There can even be excessively high voltage caused by a faulty voltage regulator. The normal range is between 13.5 and 14 volts. A jumping needle could be either a poor connection somewhere in the circuits or a failure within the gauge itself--an internal part of the instrument cluster. Find an analog voltmeter and connect it to the battery to see if you get the same jumping-needle effect as the gauge on the instrument panel. If you do, there's a problem in the charging system. If it looks good, remove fuse number seven from the fuse panel under the dash and install the voltmeter from the fuse to a good metal ground (such as the doorjamb switch). If the needle jumps, there's a poor connection from the battery to the fuse (the ignition switch is part of the circuit). If the reading is normal, you'll have to remove the instrument cluster to determine if the problem is the volt gauge itself or if it's in circuits further down the line. Solving this will require the appropriate wiring diagram and some fundamental electronic aptitude.