Your dishwasher may be making this type of noise due to a few problems that
may be occurring. Check these:
- Water-inlet valve
- Heater fan
An aging water-inlet valve can sometimes fail slowly, rather than all at once. It can shudder on and off rapidly, causing the incoming water lines to shake, rumble and rattle--sometimes violently. If yours is doing this, replace the inlet valve.
If it's the motor that's noisy, either of these may be the "culprit:"
* As motor bearings wear out, they can become quite loud when the motor runs. They wear out quickly if they frequently get wet, because the water washes away the motor bearing grease. Bearings can get wet if the spin seal is defective. Then there will also be water leaking onto the floor beneath the dishwasher. Replace the seal if it leaks (read about the main tub seal in the "It leaks" section, later).
* If, from beneath the dishwasher, you can see a round, plastic disc that's mounted to the top of the motor (a "slinger"), it may have broken free of the motor shaft. If so, it could be rattling around the shaft while the motor is running. If that's the problem, you need to replace the motor.
If the heater fan bearings are rusted or worn, they may squeal, or scrape loudly during the drying cycle. If this is the problem, replace the fan motor. Alternatively, the fan blade may be loose. If so, you need to replace it.
Small fruit pits, toothpicks and fragments of glass sometimes get stuck in the pump. When this happens, open the pump and remove the debris. The pump is usually mounted directly to the motor, then attached to the bottom of the dishwasher.
To get to the pump, you usually need to remove the lower rack, the spray arms and the spray arm support from the inside of your dishwasher. A dishwasher pump isn't obvious. Look for an impeller--a round, plastic fan blade-type device that spins around and pushes the water toward the drain. When you can see the drain impeller, you should be able to see the clogging debris.
It's hard to pin point exactly which it is unless it breaks down or you have hands on tech on location to figure it out.