Service slants

Motor, Aug 2000

GM

Second-design connecting rod bolt. GM doesn't say why, but the connecting rod bolt design was changed for the 1999 model year V8s found in the Chewy Silverado/GMC Sierra, Corvette and Camaro/Firebird. These are the 4.8-, 5.3-, 5.7and 6-liter motors (VINs V, T, G and U). The old-design and new-design bolts are shown in the illustration. What's important to remember is that either version of the bolt can be used for these engines (full vehicle application list below), as long as they're used in pairs! Mixing these two bolts on the same connecting rod "may lead to uneven clamp loads and/or connecting rod bearing bore distortion," says GM.

That makes sense. To keep them straight, note that the early-design bolt is identified by a single dimple mark on the head but no retaining sleeve on the shank. The later-design bolt is identified by two dimple marks on the head and a retaining sleeve on the shank. The early design takes 15 ft-lb of torque on the first pass, then 60deg more. The later design takes 15 ft-lb on the first pass, then 75 more.

This information applies to the 5.7liter V8 in 1997-99 Corvettes and 1998-99 Camaros/Firebirds. The other V8s are found only in the 1999 pickups.

Ford

Chirping blower motor. Ford says the blower motor on some cars and trucks (full vehicle list below) can start to chirp and/or squeak at low speeds. The noise apparently is caused by "uneven brush friction" on the commutator surface of the motor. The simplest solution, of course, is to replace the motor with a revised version. There are 16 possible part numbers to cover the following vehicles: 1984-94 Tempo/Topaz, 1986-97 Taurus/Sable/Continental, 1989-97 Thunderbird/Cougar, 1991-97 Escort/Tracer, 1995-97 Contour/Mystique, 1994-97 Mustang, 1993-97 Mark VIII, 1992-97 Aerostar, 1993-97 Villager, 1995-97 Windstar and 1997 Expedition, F-150 and F-250 LD.

Chrysler

CV boot grease seepage. The 1996-99 minivans-Chrysler Town & Country, Dodge Caravan, Plymouth Voyager-have a right-side inner constant velocity boot made of a special high-temperature-resistant material that can allow heavy grease seepage. You may actually see droplets on the boot convolutes. But, says Chrysler, although the boot may look ugly, the leak will eventually stop, and this seepage doesn't affect the function or durability of the CV joint. So explain to your customer that replacing the boot isn't going to help. Just wipe the boot clean and suggest placing a piece of cardboard on the floor of the garage until the seepage stops.

Isuzu

Rear axle leaks. A 1998-99 Rodeo may show up in your shop someday with a wet rear axle in the area of the brake dust shield(s). Obviously, the seals) is on its way out, but in addition to replacing it, Isuzu recommends that you also replace the two axle breathers (one at the diff, the other at the end of the breather hose) and the breather hose itself. Here are the part numbers:

Toyota

Revised PCM idle speed. Should you ever get a 1995-97 4x2 Tacoma pickup in the shop with the 2RZ-FE 2.4-liter four-cylinder and an automatic transmission that has kind of a lumpy idle, you should be aware that Toyota revised the PCM for this powertrain to smooth out that idle (in Drive) by increasing idle speed (a/c off) from 600 to 700 rpm. The revision also "narrows the rpm transition between a/c off and a/c on engagement." The funny thing is, this PCM never entered production. The change applies only to replacement PCMs available through Toyota's parts supply. For your information, here are the old and new part numbers:

Ford

Delayed upshift from reman 4870W trans. This symptom applies only to the vehicles listed below with a Ford Quality Remanufactured 4870W Transmission Exchange Unit with build dates between 062-97 and 040-99 (serial numbers 80475 797 and R0 7 71887, respectively). A delayed or no 2-3 upshift is the complaint, primarily when the trans is cold. In some cases, DTC P0782 may also be stored in memory. The cause is a leaking large-diameter 23 accumulator seal. The fix is to install a revised 2-3 accumulator piston (Part No. F7AZ-7H292-AB) that has tighter tolerances.

The affected vehicles are:

Mazda

ABS light on, with DTC 5. Should you ever get a 1997 4WD B-Series pickup that's turned on its ABS warning light, here's a possible cause and solution. All of these trucks built up to June 1997 with electric shift control, 4WD and rearwheel ABS may be susceptible to turning on the ABS light and storing a DTC 5 after front brake lockup in 4WD mode. This may be caused by the RABS module not sensing that the compact pickup is in 4WD mode. Mazda has come up with a service kit (Part No. ZZN0-67035) to take care of this glitch.

Ford Truck

Whistling/hissing from firom transmission.

According to Ford, the 4R44E or 5R555E automatic transmission in some 1997 Aerostars and some 1997-98 Explorers/Mountaineers and Rangers may give off a whistling or hissing sound around the main control area at idle in Drive and/or Reverse. This is most likely due to an improperly sized orifice hole in the main control separator plate. Ford has come up with nine revised plates based on the various powertrain applications. Pick up the correct one and you should have that truck quieted down in no time.