HP Color LaserJet 2840 making awful noises

front, rear ? I'd say fuser assembly gears or drum on toner cartridge; check the gear teeth on the toner cartridge's drum.

Imaging drum reach 20,000 (black only) or 5,000 (color), replace the image drum.

Supplies life
The life of the imaging drum depends on the number of black-only or color pages that print jobs
require. Imaging-drum life is also affected each time the device calibrates because calibrating causes the imaging drum to rotate. Imaging-drum life is measured in terms of number of rotations rather than number of pages printed.
The type and length of print jobs also affects drum life. A series of short print jobs uses more drum
life than an equivalent number of pages printed in a single large job. To extend drum life, print
multiple copies of a print job at one time rather than sending the same job to the device multiple times.
The life of a print cartridge depends on the amount of toner that print jobs require. When printing text at 5% coverage, black print cartridges last an average of 5,000 pages and cyan, magenta, and
yellow print cartridges last an average of 2,000 pages. High-capacity cyan, magenta, and yellow print cartridges last an average of 4,000 pages. (A typical business letter has 5% coverage.)

Hi there

Did you do a reset in the Menu or on the printer when you replaced the new drum.
All best Pineworks

pristonero, there is no "main" button. what are you talking about?

Did the noise start right after you replaced a toner? If so it must be a bad toner which is causing the gears to grind. If this noise happened out of the blue then it might be a bad fuser drive gear which is the gears that connect the fuser to the machine.

Remove toner cartirdge and check gears on cart as well as all of the gears you can see inside the unit for any signs of wear. You may also need to remove the fuser assembly and perform the same task with the gears back there. MAKE SURE THE POWER HAS BEEN TURNED OFF AND THE PRINTER UNPLUGGED FOR AT LEAST 30 MINUTES BEFORE ATTEMPTING TO TOUCH THE FUSER. IT WILL BE HOT!!! Most frequently these kinds of noises from the printer are due to gears slipping. Sometimes simply reseating the fuser assembly or toner cartridge will fix it. If there appears to be excessive wear on any of the gears, you will need to replace them.

there is something wrong with your drum.. try to replace a new chip for the drum make sure that the chip is working.... if that did not work. see if there is any damage in your drum.. If not replace a new drum..

The problem is that the revolving drum doesn't contact the OPC drum proberly. You have to open the left side off the machine and replace the little white gear on the shaft that drive revolving drum. The gear has "jumped"one step and the revolving drum isn't parallell to the OPC drum. I fixed my 2840 last night it takes some time but now it works perfect.

I first guess that it is the drum going out. If you have changed the drum......it is more than likely your fuser. Have you ran a supply check to get the status on your supplies?

Need to order a replacement FUSER it's located in the rear of the printer. If you live in the USA you need 110V if you're in Euro 220V see below for the part number you need to order.

RG5-7602-000
RG5-7603-000
Fuser ***'y, 110V, CLJ 2820/2840
Fuser ***'y, 220V, CLJ 2820/2840
CLJ 2820/2840