Shredded plastic gears are a common problem with chain-driven garage door openers. Fortunately, the repair is neither difficult nor expensive, and it should only take an hour of your time. So, if you suddenly find that the motor on your garage door opener sounds like it's running, but the door is not moving, checking for worn gears is the first thing you should do. Here are the steps involved in inspecting and replacing garage door opener gears.
If the problem you are having with your garage door opener does not seem to be related to the gears, take a look at Troubleshooting the Most Common Garage Door Opener Problems.
Unplug the garage door opener. Pull the emergency release rope, and then shut the garage door by hand. Remove the cover from the garage door opener.
Inspect the Gears
Examine the white plastic gears. Do the edges appear to be worn down or shredded, like those in the photo? If so, you will need to replace them. Find the make and model of your garage door opener, and then start shopping for a new gear kit. Amazon and other online retailers carry many popular gear kits, ranging in price from about $18 to $30. If you are in a bigger hurry, you should be able to find a kit at a local garage door opener dealer. A gear kit should contain two new gears, some washers and a tube of grease. Some gear kits come with detailed instructions that should help guide you through the process. Others contain minimal, if any, instructions, which is where this tutorial comes in.
If your examination reveals gears that appear to be in good shape, you may have a more serious problem with the garage door opener. You may want to find a good repairperson to get a professional opinion. Alternatively, you might just want to go ahead and replace the unit, which may not cost much more than the repairperson would bill you. (Here is a list of other good reasons for replacing a garage door opener.
For some advice on buying a new garage door opener, see this article.
Collect Your Tools
A typical gear replacement will require the following tools:
- 1/4-in. nut driver
- 3/8-in. nut driver or socket
- 5/16-in. nut driver or socket, with extension
- 1/8-in. Allen wrench
- flat head screwdriver
- 5/32-in. punch
Loosen the Circuit Board
On some garage door openers you may find that loosening the circuit board and letting it dangle will provide more room to work. Just remove the screws and let the board hang, out of the way.
Loosen the Chain
The chain is attached to a tensioning rod. Use a wrench to loosen the nut on the rod. Note that you may need a second wrench or pliers to keep the chain from turning.
Remove the Gear Assembly
Remove the screws holding the gear assembly in place. Lift the entire assembly out of the unit. Next, you will need to remove the helical gear from the shaft. This gear is held in place with a pin, which is removed by tapping a small punch with a hammer. If the pin proves difficult to remove (and they often do), spray some WD-40 on the pin and let it soak in for awhile.
The worm gear attached to the motor shaft can be removed by loosening the set screws on the collar with a hex wrench. Slide the gear and washers off, and then remove the retaining screws on the motor.
Reassemble the Gear Assembly
Attach the new worm gear to the shaft. Reassemble and replace the motor assembly. Now you need to install the new helical gear assembly. Put a thin layer of the grease included in the kit on the gear.
With the gears back in place, tighten the chain as directed in your owner's manual. Replace the cover on the garage door opener, plug it back in and start enjoying your now functioning garage door opener.