EFM stoker noise question

I noticed my stoker motor is pretty noisy, more noisy than I imagined it to be. Not the ratchet sound that the auger makes which is acceptable but the combustion fan makes a growling noise. I took off the 3 bolts and slid the motor/fan unit out and tightened the bolts and cleaned it and reinstalled it. The problem went away and the thing sounded smooth as silk. An hour later when the timer kicked it on again it was just as noisy as before I worked on it. So I took it out again, inspected it and everything seems OK so I put it back in and it was quiet again for a little while, now it's noisy again. What gives? I think it may be the rubber coupling that connects the motor to the gear box.

Can you remove the motor and run it disconnected from the coupling? If the noise is still in the motor, the bearings may be going. If the noise is gone, it could be the coupling, whatever its driving or the motor mounting (either misaligned or something else).

I ran it out of the housing and it's quiet. I turned the gearbox by hand and that's quiet too but I certainly didn't spin it very fast. It's possible I might have overfilled the gearbox, I took off the top allen plug and filled it up with 90w gear oil. I might try a new coupling if you know where I can buy one let me know.

e.alleg wrote:I ran it out of the housing and it's quiet. I turned the gearbox by hand and that's quiet too but I certainly didn't spin it very fast. It's possible I might have overfilled the gearbox, I took off the top allen plug and filled it up with 90w gear oil. I might try a new coupling if you know where I can buy one let me know.

Most bearing suppliers will have a big selection of couplings, Graingers would have them too but they can be pricey. If the hubs are good, just buy a replacement rubber. If the hubs appear worn at all, replace them too.
The gearbox should have a pipe plug or screw in the side for the high level. It should not be overfilled as it can damage the seals, generally they run about 1/3 full approximately. It should not be filled to the top.
The motor may run quite without a load and still have bad bearings, did you check the shaft for excessive end play?

thanks for the help. The rubber has 2 ways it can so so I switched it but it made the same noise. I also took out the top plug on the side of the gearbox and drained about a shot glass full of oil out. The oil level now is about even with the bottom of the shaft that drives the connecting rod, not the one that hooks to the motor. While experimenting with finding the sound I fixed it. I loosened one of the screws that holds the motor to the larger plate about 1/8 turn and the sound went away instantly. It looks like there should be a gasket between the motor and the plate it bolts to. If you have a parts list can you post it or send it to me? The end play on the motor is about .050" using my best guess. I put a lock washer on the bolt so I don't think it will work it's way loose but I might make a small lead shim for it so I can tighten it down my way- goodentight

Do you have an owners manual? I can send you a copy of mine if you like. I have some shims, I can throw in too if I can find them, what size are the bolts? Most motor noises are related to mounting and alignment issues. The coupling should have the story of misalignment beaten into it if that is the case. It sounds like the motor base and what it bolts to are not flat with each other causing a stress in the housing when tightened.

.050" would be a lot for a ball bearing motor (not unheard of w/bushed motors), that is almost a 1/16" end play, maybe its half of that or less?

I have the manual that is on the EFM website, if you have a better one I'm interested! I'm not sure of the end play but it doesn't seem like a lot. My "guesstimation" is usually way off. This isn't my fault. I have 4 kids, when dividing up a cupcake everyone wants half. I can take a cupcake and divide it into 5 equal pieces and everyone got "half" 8)

That is the one I have.

Any parts you need are available.

There is no gasket between the motor and the mounting plate. It was probably some harmonic noise.

It quited down to almost no noise. I loosened both screws, jiggled the motor here and there until it sounded quiet and tightened them up snug. So far so good, and it seems the longer that the thing has been running the better. The bearings might have gotten some rust from sitting when I bought it.

E.Alleg....

I would opt for the coupling being bad. If it's rubber, it may be getting too hard and the noise is vibration from the lack of dampening it. If it's broken around the "teeth" of the rubber, it could be a balance issue combined with vibrations. When you take it out and it runs fine for a short time, all it's doing is re-seating. That can indicate a broken coupling. If it's the "spider" type of coupling, look closely at it around the base of each "spoke" to see if there's any cuts or breaks. If it's the sleeve type with what looks like saw teeth on each end, any wear at all will cause this very problem you're having.
When you reinstall it, make sure (if you can) to check alignment between the drive units. A little bit off is like adding a weight to a tire. It'll throw the balance off.
If you find this still doesn't work, you can opt for a softer rubber compound for the coupling. One of the gang suggested Grainer. Good choice! They have a variety of coupling types at reasonable prices.
If all else fails - and keep in mind that I normally wouldn't suggest this - you can set the motor on vibration dampeners as long as the alignment on the coupling doesn't change too much.
Not sure of your setup as I do not have any EFMs out in the field. But I've had the problem and the above mentioned items usually take care of it.
Anyone else??