1811 PTO field melted

[Pucknut]

If you guys remember last fall, I was having some issues with many things, as this Cub apparently wasn't quite the find I thought it was.
To make a long story short, I had a lawn cart full of some rock and sod, backing it to the edge of my ditch the lawn cart went too far over dragging the 1811 backwards with it. The ditch was only deep enough that the lawn cart hit bottom with the Cub's front wheels on the top lip. After finally getting it out I had broken the rear seal, the automatic reliefs were shot, and on and on... Used this as a perfect excuse to get some additional parts to repair everything that I knew needed to be done.
However the PTO was not touched as it was working perfectly. Not so any more. I took it out to mow and about 8-10 minutes in she started smoking. Not my typical burning oil smell, and parked it and found a mouse half cooked around the heat shield and the head. Figuring this was what was grilling, I took it out for the rest of the day fine. The next time I took it out to mow it did the same thing, but the PTO quit on me. Tore it apart to get to the PTO and the potting on the field had melted, letting the windings get pulled into the directly keyed PTO disk. Needless to say this field was shot.
I found myself a new field, and installed everything, even tipple checking the air gap as I thought that this could have been the culprit (I knew I hadn't checked this at all...) figuring that an excessive air gap could have been the source of the heat that caused the potting to melt.
New field lasted about 2 minutes before it started smoking and I shut it down...
The new field is drawing just a hair over 4 amps when engaged, so that shouldn't be the cause of the heat. Any ideas as to what else I need to look at?
The new field can still be useable if I can find the melting point of the potting to push the field back into the housing and reseal it as it didn't wear through any wires in the coil.

[darkminion_17]

I would have thought the fuse would have blown the first time it happened.
Check to see it is the correct one as the po may have put the wrong one in.

[J-Mech]

Was the field you got new? Or used? Check your grounds. The field coil base grounds through the base to the engine block. The only thing I can think of that would cause the field to get too hot, it bad internal windings. I don't think even a bad ground would cause this. I believe it would just make the magnet weak. The air gap doesn't affect that either, it just affects how hard the magnet holds the PTO.

[Pucknut]

The two fuses I have in I believe are the correct fuses.
The field was a brand new field.
I just checked all the grounds, and all have good contact (no resistance on the multimeter)
After being pissed off at this for a few days, looking at it this morning in a 'different light' just showed me that the keyed clutch disk is rubbing on the lip of the field. (the brand new field lip is worn and showing a bit of mushrooming.)
So I think I found the cause of the heat that's melting the potting. Metal on metal at 3600 RPM I believe would put off a lot of heat...

Is there supposed to be a washer/spacer on the engine shaft that holds the keyed clutch disk off the field? As this seems to be the only explanation that *IF* there was one there previously that it degraded/rusted out and caused this to become a 'sudden' problem. There would be no reason for the old field to pull out to rub the disk, and the new field is properly mounted and torqued in place with no debris/obstructions behind it on the engine block to hold it further out from the block than what was designed...

[J-Mech]

Originally Posted by Pucknut

"the keyed clutch disk is rubbing on the lip of the field. (the brand new field lip is worn and showing a bit of mushrooming.)
So I think I found the cause of the heat that's melting the potting. Metal on metal at 3600 RPM I believe would put off a lot of heat...

Is there supposed to be a washer/spacer on the engine shaft that holds the keyed clutch disk off the field? "

That will do it.

Part book doesn't show one.

PTO.gif
http://www.partstree.com/parts/?lc=c...&dn=0029900010

[inspectorudy]

I've got a coil and disc if you want it for $60. It's the one wire coil.

[rweaver]

if the bearing is bad had that take out a bunch of coils this summer if that was mine I would use a small shim stock to hold it away as long as you can get your 0.10 clearance there is a bunch of coils man is it fun when guys don't know what they have

[Pucknut]

Originally Posted by rweaver

if the bearing is bad had that take out a bunch of coils this summer if that was mine I would use a small shim stock to hold it away as long as you can get your 0.10 clearance there is a bunch of coils man is it fun when guys don't know what they have

Which bearing would this be? And how would it being bad cause this?
And as a temporary fix a washer/shim on the end of the crank behind the key is one possibility, the second being to grind down the lip of the field a hair. With the shim being the easier way to go.

Inspectorudy, If my attempt to repair what I have fails, I will more than likely be knocking on your door for that offer.

I'm pretty sure I found the cause of the heat which caused the field potting to melt, however, I do not yet know what caused the metal on metal rub of the fixed/keyed disk to the field assembly's lip.

[rweaver]

I would file it down not grind as the heat from the grinder is the same heat as before I don't know why the heat from the bad pto bearing causes the ooz to come out of the magnet but seen it few times

[Oak]

If part #2 is rubbing on part #1 something isn't right. I did several and never had that problem. We need some pics. Any pto I take apart gets new bearings and you need a 6206 double sealed for the one your working on. They are easy to change and should cost less then $20 if your buying only 1.