Service slants

Motor, Aug 1999 by Juran, Ken

Ford

Serpentine belt lets go. When Ford replaced its ancient 5-liter V8 with the modern OHC 4.6-liter modular V8 some years ago, everything seemed to go smoothly. There haven't been any major problems...except for the Mustang. Because it's a pony car and a muscle car, the 4.6-liter in its SOHC and DOHC variants sees a lot of high-- revving action with subsequent rapid decelerations, especially when coupled to the five-speed manual transmission. It's these decelerations that tend to overwork what Ford calls the Front End Accessory Drive (FEAD)-the serpentine belt drive, to the rest of us.

Affected models include those from 1996-98 with the five-speed. You'll see damaged belts, belts that have completely come off their pulleys and shredded to bits and noisy accessory drives. The fix involves installing new water pump and power steering pulleys that have flanged edges to keep the belt running true, and a new tensioner assembly to keep the belt from slacking off on the job. If you get a late-model, you might find the new pulleys already there. In this case, just replace the tensioner with a new belt.

Here are some tips to smooth your work: The flanged power steering pulley must be positioned .67mm past the end of its shaft. On the bottom of the power steering pump is a power steering line orientation clip. Ford says to chuck it and install a new-design clip.

Turning your attention to the automatic tensioner, look for a positive stop installed over the tensioner. If the part number stamped on the bottom of the stop is F7ZE-19A439-AB, it means you can toss both this stop and the tensioner. If you find no positive stop, just remove the two bolts and one nut that mount the tensioner to the engine. Throw everything out except the nut. Now, mount up the new steel tensioner with the one existing stud and nut that you saved, plus two new studs and nuts. Torque all the studs and nuts to 15 to 22 ft-lb.

Next, route the new belt around the accessories. Then put in the new Tensioner Positive Stop. It mounts over two of the tensioner studs and is held in place by two more nuts torqued to 15 to 22 ft-lb. Here are all the necessary part numbers:

GM

ABS light on, DTCs 21 & 22. Be aware that a bad wheel speed sensor connector may turn on the ABS light in a 1995 Buick Skylark (built from VINs C406400 to C412300), Oldsmobile Achieva (built from VINs M309800 to M316940) or Pontiac Grand Am (built from VINs C723200 to C742000 or M520300 to M535300). DTCs 21 and 22 will probably set, indicating a broken wire in the front wheel speed sensor connector at the back of the terminal crimp.

Note that these cars were built in October 1994 and have tape on the leads to the back of the front wheel speed sensor harness connectors. GM wants both leads repaired if the DTCs lead you to an actual failure. There are two kits available-Part Nos. 12140077 (left wheel) and 12140078 (right wheel)-that contain instructions, splices and pigtail connectors.

GM says these kits "will alleviate repeat failures." That's probably because the jumper is long enough to ensure a safe splice location out of suspension flex zones. The splice will be located in the main branch of the engine harness, away from the control arm.

Dodge Truck

Exhaust drone at idle. You may get a complaint of an annoying exhaust drone at idle from owners of 1994-95 Ram Vans or Ram Wagons. The noise and accompanying vibration through the brake pedal, steering column, seat and floor make themselves known in Drive when the engine is up to operating temperature. Anywhere slightly above idle and all is quiet.

Dodge has come up with a Steady Rest Bracket and Clamp Kit (Part No. 4797312) that you add to the exhaust strut on the transmission to eliminate this grievance. To do the job, loosen the left engine-to-trans strut bolt just enough to slide the steady rest bracket into place. Once the new bracket is in position, retorque the strut bolt to 50 ft-lb. Then locate the kit's clamp saddle between the steady rest bracket and the exhaust Y-pipe. Clamp the whole thing together with the kit's U-bolt to 17 ft-lb to complete the fix.

Chrysler

The Y2K bug. As Bob Savasta pointed out in his April '99 Trouble Shooter column, the Year 2000 two-digit calendar year computer dilemma is unlikely to affect automotive computers. Here's the official word from Chrysler: "Two-- digit calendar year codes have not been used in any [Chrysler, Dodge, Plymouth, Eagle, Jeep or Dodge Truck] automotive onboard applications and no problems related to the use of two-digit coding for calendar years are anticipated."

GM

DA-6 vs. HR-6 a/c compressors. According to Everco Temperature Control, GMs DA-6 a/c compressor was used extensively on GM vehicles from 1983-86. In 1987, GM started using the improved HR-6 design, with its larger, stronger and more efficient internal components. But the HR-6 can be interchanged with the DA-6 and is listed as a heavy-duty service option for most applications.

The HR-6 lasts longer in R-12 applications and has no trouble handling the potential higher head pressures of an R134a retrofitted system. So if a DA-6 is being replaced as part of a retrofit job, the HR-6 is the unit to use. On those applications that list the HR-6 as the heavy-duty version, it can be installed without any vehicle modifications or adapters. If you have any doubt, compare the two in the illustration section of the manufacturer's catalog.