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  • TDC - Technical Questions & Answers - February 2004

TDC - Technical Questions & Answers - February 2004

Questions & Answers

Bruce Caldwell
Feb 1, 2004
Belting The Blues
I bought a fairly high-mileage '92 GMC Sonoma with the 4.3L V-6, automatic transmission, power steering, power brakes, and air conditioning. The truck came from Arizona, so I assume it was driven under hot conditions. All the hoses and belts in the engine compartment were quite worn. Many were checked, cracked, or otherwise showing lots of hard use. I replaced everything, including the big serpentine belt on the front of the engine.
Things seemed OK for a while, but then the serpentine belt started squealing loudly. It doesn't always do it, but it does it enough and when it does, it's very annoying. I followed the diagram on how to route the belt, but I don't know how else it would work if it wasn't routed correctly. The serpentine belts aren't cheap, so I'm not too big on replacing an almost-new belt. Can you suggest what might be causing the squealing?
Robbie Alvord, Peoria, Illinois
A: There is a very slight possibility that you bought the wrong belt. You need the correct belt for the engine and accessories on your truck. You could note the part number on the belt and have it double-checked. Your serpentine belt is self-adjusting, so the belt would have to be quite wrong for that to be the source of the squealing.

A way to check if the belt is causing the noise is to pour a few ounces of water on the belt while the engine is running. If the noise stops briefly, but quickly comes back, then it is the belt that's making the noise.

You can also look across the belt and pulleys to be sure that they are in proper alignment. If one side of a pulley groove or one side of the belt seems much more worn than the other side, that could indicate an alignment problem. A metal straight edge is more accurate than a visual inspection for confirming pulley alignment.

A trick that can provide temporary relief from a noisy belt is to reverse it. Remove the belt and flip it before reinstalling it. The side of the belt that previously faced the radiator should now face the engine.

The source of the noise is more likely the idler pulley or a pulley on one of the items driven by the serpentine belt. The idler pulley is the first one we would suspect. Spray some WD-40 on the shaft of one pulley at a time. If the squealing stops momentarily, you've probably found the culprit. Remove the belt and try to wiggle the suspected pulley; any looseness is a further indication of a failing part. The failing part should be replaced as soon as possible.
Leaking And Lurching
My '94 Nissan Pathfinder is starting to show its age. A number of problems have surfaced recently. The two that bother me most are a coolant leak and an automatic transmission that doesn't shift very smoothly. The truck has the 3.0L V-6. The odd thing about the transmission is that I serviced it less than a year ago. I drained the fluid and replaced it with fresh automatic transmission fluid. I dropped the transmission pan and inspected the residue in the bottom. There was some gummy stuff, but there didn't appear to be any metal shavings. I rinsed the filter screen and reinstalled it, and I used a new pan gasket.
Now the transmission shifts poorly when I first start out in the morning. It works better after I've driven for a while and the truck has warmed up. Do you think I might have overlooked something or upset the transmission's internal balance by changing the fluid? Could this be a sign of more trouble in the future?
The leaking engine coolant is a bit of a mystery. I'm not completely sure where it is coming from, but it appears to be the front of the engine. I've carefully observed the radiator and related hoses; I can't see any obvious leaks. I figured the most obvious source was a bad head gasket, but I haven't observed anything, such as unusual exhaust smoke.
I called a couple local shops to see how much they charged for replacing a head gasket. They tried to sell me more services, such as doing both heads and having the heads checked for warpage and then resurfaced. Couldn't I just skip the machine work and install a new gasket?
One shop suggested that the problem might be a loose coolant jacket plug, and it wanted a lot of money to replace an inexpensive little plug. I'm not sure what to do, so I'd appreciate your input. Of course I'd love to know some easy, inexpensive solutions.
Mike Maas, Springfield, Missouri
A: We'd all like our mechanical problems to be easy, inexpensive, and quick to fix, but that's rarely been our experience. Maybe each of us has a cosmic mechanical counterpart somewhere in the world that always has an easy time with repairs. I'd like to meet that person.

There might be an easy solution to your transmission problem. You didn't mention the type and brand of transmission fluid you used, but if it wasn't official Nissanmatic type-C fluid, maybe it should have been. Other '90-'95 Nissan Pathfinders have reported cold shifting problems, and the tech people have strongly advised using only the Nissanmatic type-C fluid. Try thoroughly draining your old fluid and replacing it with the factory-approved juice. You might luck out on this one. If the problem persists, take the truck to a transmission shop.

As for the coolant leakage, the solution isn't as simple. We tend to side with the shop that suggested a bad coolant plug. The '90-'95 Pathfinders sometimes develop a coolant leak at the plug that's located behind the camshaft drive components. Since the plug is under the sprocket, quite a lot of time and labor is required to reach the loose or defective plug. Cleaning the threads and installing a new plug and thread sealant is easy and inexpensive; it's just getting to the plug and reassembling everything that costs so much.
Key Problem
Sometimes my '86 Chevy Silverado won't start in Park. I end up doing things such as wiggling the key, taking the key in and out a couple times, and moving the gear selector through the gears and back to Park. The truck will start in Neutral, though. I had a replacement key made, but that didn't seem to make much difference. This intermittent starting problem can be very annoying. Can you offer me any advice?
Dan Montgomery, Houston, Texas
A: Our advice: Don't rob banks or try to start your truck on a railroad crossing. Given the age of your truck, there are a couple possible sources of the problem. A truck this old has been started thousands of times, so the ignition and Neutral safety switch have had lots of use. If the problem seems more related to wiggling the key, you might need a new ignition switch. Key rings with lots of keys or heavy attachments, such as a knife, can cause premature wear on the ignition switch. The replacement key might not have been as accurate as it should be since it was patterned off an already worn-out key. The quality of a replacement key can also depend on the skill of the machine operator. If the problem seems more related to moving the shifter, the Neutral safety switch could be due for replacement. The shift linkage could also be out of adjustment.
Clueless About Keyless
This isn't a big deal problem, but I still hope you can help me. Other GM truck owners might have the same problem. When I approach my '99 Suburban from the rear and try to use the keyless entry fob, it barely works. I have to get right next to the truck before I hear the doors unlock. I don't seem to have this problem when approaching from the side. What gives?
Darrell Remlinger, Lakewood, New Jersey
A: There seems to be a technical service bulletin for just about everything. Other '97-'99 GM Suburban and van owners have complained about similarly poor keyless entry performance. The answer, according to TSB 89-90-06, is to lift the fob to shoulder height or higher to increase its range. This reminds us of the lame remote control unit on our television.
Bad Pad
One disc brake pad on my '94 Chevy Silverado Extended Cab wears out much sooner than the other pads. The front-left outside pad has a wear rate two or three times as great as the other front pads. I put about 25,000 miles a year on the truck, and I frequently tow a 24-foot travel trailer, so I replace brake pads more than the average truck owner. I do my own pad replacement, and I've done it so many times that I can almost do it blindfolded. I've tried using different brands of brake pads, but haven't noticed any substantial differences. I generally stick with one brand because I like those lifetime replacement guarantees. I make out like a bandit on free replacement pads. Still, I'd prefer doing the brake jobs less frequently. What would make one pad wear faster than the others?
Bill Schaeffer, Mesa, Arizona
A: It sounds like the left caliper is hanging up. If the caliper doesn't slide smoothly as it is applied and released, the wear on the inner and outer pads can vary. You seem to have a pretty extreme example of this problem. Somewhere in the caliper mounts or pins, excessive friction is occurring. Something is sticking or binding from being bent or worn out. Judging by the high mileage on your truck, wear would be a safe guess. You should inspect and replace as necessary all the disc brake mounting hardware. You can get hardware kits with new bolts, retainers, sleeves, and dust boots. You might also want to replace the caliper mounting bracket. We assume that you periodically have the rotors turned and replaced.
Photo 2/3   |   tdc belting The Blues
Photo 3/3   |   tdc clueless About Keyless
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