Question: I have a 1999 Dodge Dakota with
the 3.9-liter V-6. I recently started hearing a loud rattle coming from the
front of the truck. It only makes the noise when the engine is hot, and only when
I race it to about 2000 rpm. Any ideas what it could be?
Answer: When dealing with engine noises, the most important asset is experience. Not as much because of the technical knowledge, but because you've heard so many noises over the years. Often you'll have a good idea of what the problem is with a quick listen. Here are a few things you can do before you go find a tech: Remove the drive belt and run the engine. Is the noise still there? If not, you've just narrowed it down to a component driven by the belt, such as the power steering pump, A/C compressor, or belt tensioner. If that's the case, listen to each component with a mechanic's stethoscope (or a screwdriver to your ear) while you spin it by hand. A lot of times you can hear a worn-out bearing loud and clear with this method. If the noise is still there with the drive belt off, it may be an internal engine failure -- but not always. I've seen loose transmission and torque converter bolts mimic an engine knock, and it could be something on or near the engine rattling from engine vibration. You want to duplicate the noise. Hold it at 2000 rpm and go under, over, and all around the engine using normal hearing and a stethoscope, attempting to narrow down the area. Again, you can drive yourself crazy trying to figure it out, while a senior Dodge tech might know what it is right off the bat.
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If you have a technical question regarding your pickup, SUV, or van, feel free to contact Alex, a master technician with the National Institute for Automotive Service Excellence. Send a letter to him in care of Truck Trend Garage, 831 S. Douglas Street, El Segundo, CA 90245, or e-mail us at email@example.com. Please include the VIN with your question. Due to the volume of questions received every month, we cannot guarantee that everyone's question will be personally answered or will appear in the magazine.
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