The primary function of your GMC K1500's exhaust system is to efficiently transfer toxic gases from the engine to the tail pipe. Since the exhaust system works under high temperature, it will eventually wear down and malfunction. Rattling or roaring noises can be one of the early signs of a poor exhaust system. If these symptoms are already present, then you have to look under your vehicle and perform a troubleshooting. Here are some common problems you might encounter with a malfunctioning GMC K1500 exhaust system.
Your truck's engine usually produces a loud, revving sound when the vehicle accelerates under load. That's one of the reasons why it is tuned correctly to dampen irritating, high-pitched tones. Some vehicles even have a second muffler or resonator to control the noise. When the parts of the exhaust system, particularly the exhaust pipes are already in poor condition, the annoying high-pitched noise becomes audible, and the sound will become louder as it exits through it tail pipe. You should immediately inspect the pipes for holes or cracks, and check if it is possible to weld them. Otherwise, buying new replacement parts is the only solution.
A bad exhaust system can result to backpressure because exhaust gases aren't effectively removed. This will decrease your truck's performance and increase fuel consumption. To measure your truck's backpressure through the exhaust manifold, an air pump check valve or pressure gauge can be used. The reading in the check valve should be less than 1.5 psi. If it goes further than 3 psi at 2,000 rpm, then there's already a restriction present. An 18mm pressure gauge can also detect backpressure, but it won't be able to determine where the backpressure originates.
If you step deeply on the gas pedal of your truck, but the vehicle fails to accelerate with force, then it may be sign of a plugged catalytic converter. The poor acceleration is caused by the unburned fuel that is present inside the converter. A good way to check the converter is by removing it from your truck and aiming a flashlight through its tube. If the light doesn't pass through to the other side, then it means that the converter is plugged, and has to be cleaned.