Dear Doctor: I own a 2003 GMC Sierra 1500 pickup and now have a clunking sound in the steering column. A mechanic said the sound is where the column goes into the gearbox. There was a recall, but I never got notification. I understand that even some of the vehicles repaired under the recall still have the problem. Do you have the solution? Robert
Dear Robert: An ongoing problem on this model-year truck has been the lower steering shaft failure. GM had a grease repacking kit for a while and now an updated lower steering shaft. I have replaced a number of these steering shafts over the years. As for any recalls, check the dealer service department with your VIN number. I can say that your vehicle will feel like new once the shaft is replaced.
Dear Doctor: My 2000 Mercury Grand Marquis was in a flash flood and a wave of water passed over the hood. After riding a short distance (2 blocks) my engine started to knock. I was 10 blocks from home, so I drove home and put the car in the driveway. My mechanic came over and towed the car to his shop. After checking it out, he found a piston was bent and he replaced it. Even since, the car runs as though the engine is missing when it’s idling at traffic lights. If I put the engine in neutral the roughness stops. Hope you can help. I love the car! Ray
Dear Ray: The roughness at idle speed indicates the engine is not firing completely on all cylinders. A weak cylinder vacuum leak or other worn component can cause a rough idle. Have the technician perform a cylinder balance test. Using a professional scan tool (in mode 6), the technician should be able to look deep into the computer for information. A weak sealing valve will also cause a rough idle.
Dear Doctor: My 2003 Ford Explorer has an intermittent thumping noise coming from the suspension or drive chain. It is perplexing because it only happens when the vehicle is warm. During the recent subfreezing temperatures, I could drive all day without hearing the loud thumping. Once the temperature is above 40 degrees F, it thumps. The dealer replaced the rear hubs, but that didn’t resolve the problem. I was also told it was road noise that I was hearing. It is clearly not road noise. Do you have any ideas that I might suggest to my mechanic? Jonathan
Dear Jonathan: If I were servicing your truck I would first want to know whether thump happens when your foot is on the brake, gas or just coasting.