Watertight '99 Silverado Pickup Bed
Q: My '99 Silverado Pickup has two holes (not the stake pockets) on both front corners of the cargo box between the bed and cab. Run your fingers along the forward top edge, and you can locate them. A lid or cap won't keep the cab watertight. Will Chevrolet correct this?
A: Take a closer look at the Silverado's cargo box. The holes you're describing don't go through to the interior at all. They're open to the area between the exterior body panel and the side cargo-box wall. This area is wide open at the bottom. We're confident the holes were either part of the manufacturing process and/or were used for ventilation purposes. Pickup trucks weren't designed to float. You may notice drain holes in the corners. Installing a cap will keep the bed interior dry unless the water level reaches the door handles.
'91 Jeep Cherokee Power Locks Won't
Q: My '91 Jeep Cherokee has power door locks that stopped working. The keys work, but not the power buttons on both doors and remote.
A: The power-door lock setup on your Cherokee consists of several components: The master door-lock/power-window switch assembly, and RH door lock/switch assembly, a keyless-entry module, separate lock and unlock relays, and, of course, the door-lock motors located within each door. The system is powered by two sources: the 10-amp dome fuse and the 30-amp power-accessory circuit breaker, both of which are located at the fuse panel. A number of possibilities exist that may completely disable the system, but check the fuse and breaker first. If they're confirmed good, check if there's power supplied to both components, then investigate the circuit voltage and grounds at the lock and unlock relays. The schematic shows a common ground that would kill all power door-lock operation if lost. But you may not be ready to tackle a complex electrical repair. If the fuse and circuit breaker look good, ask a technician to further diagnose the problem.
'89 Jeep Cherokee Oil-Pressure Problems?
Q: I drive an '89 Jeep Cherokee with the 4.0L engine (123,000 miles). All six connecting-rod bearings have failed, but the main bearings look like new. The engine is original, the oil pump looks perfect, and there's no sludge. Can you suggest why connecting-rod bearings failed and everything else appears in great shape?
A:The 123,000 miles on the clock is a major contributor. Most of the time, connecting-rod bearings will let go before the crankshaft main bearings when a tired engine is on its way out. Once that first fatigued bearing has enough excessive clearance, it'll spin within the connecting rod and its endcap. This allows oil pressure coming from the oil pump to free flow due to lost restriction at the bearing. Then the oil pressure will drop and aid in shortening the life span of the remaining worn-out rod bearing. The main bearings are larger and stronger and may hold up a little longer, but usually you'll have to pull over once that loud knocking noise outplays the radio. The cause can be from a number of sources such as an oil-pressure loss from a faulty oil-pump relief valve or worn camshaft bearings. The oil may have somehow been contaminated, or its time simply has come (and no one will ever know the exact cause of death). It's going to require a complete overhaul without missing a trick, so whatever contributed to the first failure is no longer an issue the next time around.
GMC Envoy Limited-Slip Advantages
Q: I plan on buying an '02 or '03 GMC Envoy with four-wheel drive. I live in Wisconsin where I experience all the joys associated with winter driving. What are the pros and cons of a limited-slip differential?
A: If you're looking for additional traction in foul-weather conditions, a locking differential is probably the way to go. It boils down to having both rear wheels pushing your SUV as opposed to one or none at all. According to General Motors, it doesn't use a "limited-slip" differential in any of its trucks. It's actually a mechanical full-locking differential that provides significant advantages over a limited-slip in poor-traction situations. The basic purpose behind a differential is to allow rear wheels to move at different speeds when making a turn. This mechanical wonder prevents us from dragging a wheel or breaking an axle during cornering. The drawback to a standard differential is the limited amount of traction it's going to provide. When one wheel loses traction, it'll continue to spin while the other wheel sits and doesn't help at all. This is where General Motor's locking differential has the advantage. When a difference in rear-wheel speeds of about 100 rpm is detected, the mechanical device within the differential locks both axles together and therefore turns both wheels in unison for optimum traction. The system becomes disabled when poor traction is no longer an issue, or, for safety reasons, when vehicle speed hits 20 mph. The locking-differential option, made by Eaton (Option Code G80) on the '02 Envoy goes for about $270 retail, and, depending on your application, is well worth the investment, the same way ABS and traction control are also big advantages in extreme winters.