[cgoll]

Our garage door opener suddenly failed. Lift Master brand. When you press the button (or remote) the light comes on but the head unit just hums. Almost like the gears are siezed.

I took the chain off the drive sprocket. No change in the situation. The door itself works fine when disconnected.

I used a channel locks on the sprocket to try to unstick the gears but there is no play there.

We have two standard size garage doors each with a separate opener. The units are likely original to the house (1989).

I had to replace the plastic gear sets in both shortly after we bought in 2000 after they both stripped within 6 months of each other, but that failure caused the motor to run but not move anything.

Now it seems the motor is trying to move the door but facing insurmountable load. (Again, note it is the same with the chain off the sprocket.)

Any thoughts?

Thanks!

 

[Robo_geek]

Our garage door opener suddenly failed. Lift Master brand. When you press the button (or remote) the light comes on but the head unit just hums. Almost like the gears are siezed.

I took the chain off the drive sprocket. No change in the situation. The door itself works fine when disconnected.

I used a channel locks on the sprocket to try to unstick the gears but there is no play there.

We have two standard size garage doors each with a separate opener. The units are likely original to the house (1989).

I had to replace the plastic gear sets in both shortly after we bought in 2000 after they both stripped within 6 months of each other, but that failure caused the motor to run but not move anything.

Now it seems the motor is trying to move the door but facing insurmountable load. (Again, note it is the same with the chain off the sprocket.)

Any thoughts?

Thanks!

The sprocket bearing seized/broke, causing the gears to jam. Chain drive units put a lot of lateral force on that bearing, and when it goes, the gears all jam together.

It's also possible a motor bearing simply seized.

 

[Ron6519]

Disassemble the head and inspect it. If you can get the parts, you can try to repair it. If not, replace it.
Ron

 

[ohdc04330]

The unit should be replaced. Finding parts for pre-1993 models may be difficult as many of those models have been discontinued. Service providers are unable to repair models that do not have safety features as required by UL325. New garage door opener models come standard with some form of reversing feature, either photo eyes or reversing safety edge. A brand new operator is also covered by a warranty in case of future problems.

 

[cgoll]

It has all the safety features (eyes and reversing). I guess I'm undecided if I want to tear it down (again) or just replace it. The gears weren't too bad to do, just not sure it's worth it on a 22 year old unit. And yes, parts availablity may force my hand.

 

[ohdc04330]

Some places still offer free estimates. You could ask for estimates from garage door companies that reflect service versus replacement of the unit allowing you the ability to compare price points. Considering the age of the unit they'll most likely recommend replacing it which you could do on your own, but maybe that will help steer you in the right direction.

 

[iamrfixit]

Chamberlain actually builds your liftmaster opener, they also are branded as sears, chamberlain, master mechanic, do it best and probably a few others.
Actually very little has changed in the chamberlain openers other than the electronics. Finding parts should not be much of an issue. The most common problems with these units are the plastic gears and the bearings on the sprocket shaft. Usually due to an over tight chain, I have seen the bearings worn so badly that the sprocket shaft gets cut deeply or even sheared off. The sprocket shaft, bearings and gears are readily available, if the problem is more serious than that I would replace the whole opener. It is possibly due for the above mentioned parts anyway, any further problems only adds on to the tab.

Doesn't make sense to put very much money in something 20 yrs old when you can get a complete new opener for $160 with modern and more secure code technology, modern safety features, more compact remotes that reach greater distance and even keyless entry. Chamberlain/sears chain or belt drive openers are a good choice and the only one I ever recommend.

 

[cgoll]

OK, here with the post-game wrap-up...

I took down the head unit and opened it up.

The gears look fine; no significant wear or missing sections. (Last time I had to replace the gears there was a large amount of plastic "snow flakes" from the stripped gears inside the housing.) So...not seized gears. I was hoping this was the case as Sears has the parts and the set is $25. But, no such luck for me...

There is a shaft off the back of the moter and a resolver off of the other end of the motor shaft. Both can be used to freely spin the motor. So...not frozen motor bearings.

When I spin the motor, the limit switch shafts also move appropriately, so that's not it either.

Anyway, end of troubleshooting for me. Bad capacitor? Bad circuit board? Bad motor windings/bushings/rotors/???

No idea. But it's not worth my time at this point.

However, maybe someday, someone using the search function may someday find this helpful!

Stay tuned for a new thread on selecting a new unit.

Iowa mrfixit; Thanks for the link; I am definately considering it. Your advice welcom in new thread tomorrow!