Ammonia smell from a motor

So I have a buyer coming to inspect the Hardinge UM I'm selling and plug it in for the first time in months just to be sure everything's working. This is minutes before he arrives - as an afterthought. Sh******t.

I converted this mill to single phase long ago, so this is a capacitor start motor. When it started there was a loud rattle coming from underneath. At first I thought it was just that the motor was bouncing and the belt wasn't tight, but the circuit breaker / heater kicked out. I looked inside and didn't see anything. I turned the motor and the spindle wasn't tight. I didn't smell anything at that point. I reset the breaker and turned the motor on again. It started and ran, but this time smoke collected inside the mill base, so I shut it off. It had an ammoniacal smell, not like the usual burnt winding or burnt electronics smell. The motor didn't feel hot, but I didn't spend a lot of time feeling all over. I told the buyer about the problem and ran it for maybe 5 seconds just to show that the motor still ran and might be repairable. I knocked $100 off the price and we were both satisfied. Since he put a deposit down, I'm not going to mess with it since now it's really his machine, but I'm curious. Was this a capacitor that was going bad? Is there anything else on a motor that might smell like ammonia? The motor is probably vintage

50s or 60s, so it's not ancient. It has grease fittings and as we've discussed here before, overgreasing can kill the bearings, but it didn't seem to have siezed bearings. The spindle turned freely. It just made an unusual vibrating noise and smoked the second time I ran it.

RWL

Ammonia means nitrogen, which means animals or plants, not something typically electrical. Usual suspect is el raton.

Yup. I had a Fanuc E-310 robot that was giving random limit errors. I eventually opened it up and found sound deadener (we used that) and that aroma. Mice crawled up the vacuum port (clean room robot not in a clean room) and set up home next to a nice warm servo motor. They tried the limit switch wiring for taste and must not have liked them that much.

Wes

eventually opened

the vacuum

You sure do not want them to like the taste of your wiring. :)

Mice set up home in my old generator once. Amazingly they did not damage anything permanently once I cleaned out their nest. I placed moth balls there and in the shed and since then, no problem. But it is not something that you can do in a garage, due to ill health effects.

Darn. If it was, I hope I got the critter that's been chewing up things in my drawers and leaving its droppings. The traps haven't caught anything. That could explain why the smoke seemed to be coming from the top of the mill base rather than from the motor. I thought it had just accumulated there, but now I suspect it was coming in from the external forward reverse / high low speed electrical switch box on the right side this machine.

Thanks to all who replied. This newsgroup is an excellent source of experience.

RWL

Or, possibly, do you have a dog that is treating the motor like a fire plug?