[Cruisin'n5thgear]

318 deck shut down last night mid-mow, and battery light came on. Pto light remained on.

Shut it down and tested per the shop manual, good power at the pto wire. Pulled the coil and it read at 0 ohms initially, then climbed to 1-1.2 ohms. The coil wiring had started to work loose and rub against the clutch.

Was able to re seat the magnet and finish the job, but the coil did not re engage the clutch when hot at the end of the mow.

Here's hoping my spare engine has a good PTO coil!

 

[Alien5044]

Despite the loose wires you found, is your battery up to keeping the PTO engaged? An electric PTO is a pretty heavy amperage pull. If the battery light came on as this quit, maybe it is just too much for an aging batter.

Even an extremely weak battery will often give a 12v plus meter reading, but the ooomph of required amperage just is no longer behind that 12v so big draw items like the PTO, just quit.

 

[biker3777]

Common issue on old pto s,when you put the other coil on,loosely put the 4 bolts in the coil,wrap 3 rounds of masking tape around the coil,slip the rotor over the coil,now tighten the coil down,pull the hub,remove the tape,now you have equal distance between the two.

 

[Cruisin'n5thgear]

Despite the loose wires you found, is your battery up to keeping the PTO engaged? An electric PTO is a pretty heavy amperage pull. If the battery light came on as this quit, maybe it is just too much for an aging batter.

Even an extremely weak battery will often give a 12v plus meter reading, but the ooomph of required amperage just is no longer behind that 12v so big draw items like the PTO, just quit.

It's a newer battery and once I seated the PTO, it ran without the battery light on for the rest of the mow.

Should be fine, about a 12 amp draw based on ohms versus three for the replacement coil.

 

[Cruisin'n5thgear]

Common issue on old pto s,when you put the other coil on,loosely put the 4 bolts in the coil,wrap 3 rounds of masking tape around the coil,slip the rotor over the coil,now tighten the coil down,pull the hub,remove the tape,now you have equal distance between the two.

Nice. I like this trick.

I'll give it a try.

 

[biker3777]

It the wires are bare you are close to failure

 

[Cruisin'n5thgear]

 

[Cruisin'n5thgear]

So you're saying this one is toast?




Haha got the new one on. Apart from mounting it incorrectly the first time, install went smoothly and it's running better than ever.

Parts stash for the win! Been holding onto a junker b43 off a parts 316.

For those who may read this in the future, bad coil read about 1 to 1.2 ohms. Good used one came in around 4 cold and 2 hot.

 

[RussKish]

From the wear pattern, make sure you triple check the air gap (0.018"), go around multiple time with the feeler gauge.

 

[dave_r]

12A is on the high side for electric pto's, it's my understanding they are normally in the 6A range.

 

[Cruisin'n5thgear]

Good to know, that checks with the 2 ohm hot reading.

Double checked the air gap multiple times. The coil melted and slid out, shorting against the rotor. Doesn't look like in the photo because I slid it back into position and finished up the mowing. Would not re engage when hot, for obvious reasons.

 

[biker3777]

If you look at the side of the coil where it’s bad,I bet you will see a spot that was rubbing the hub from improper fitting and caused it to create heat and melt the resin in the coil,did you put anti seizure on the crank to assure the hub stays free to move on the crank,they seize over time and must move the .018 to Make the pto work.
Looks like you did a good job on your toenails.🤣🤣🤣

 

[Cruisin'n5thgear]

If you look at the side of the coil where it’s bad,I bet you will see a spot that was rubbing the hub from improper fitting and caused it to create heat and melt the resin in the coil,did you put anti seizure on the crank to assure the hub stays free to move on the crank,they seize over time and must move the .018 to Make the pto work.
Looks like you did a good job on your toenails.🤣🤣🤣

I didn't do the anti seize, thanks for the tip.

I'll check out the old one. Might be, I did recently adjust the air gap as the old one was getting weak.

With the crank bolt holding the clutch and rotor in place, how does the assembly have the freedom to move? I'm still confused how it works exactly.

Spaced it out with a .040mm gage as I don't have inch feeler gauges. Err on the wider side?

 

[Cruisin'n5thgear]

And the better half snuck in the photo 😅

 

[RussKish]

That maybe to wide (0.040")

Here is how a PTO clutch work : How Does an Electric PTO Clutch Work in a Mower? - Expedia Choice

Youtube animations:

and

 

[biker3777]

I didn't do the anti seize, thanks for the tip.

I'll check out the old one. Might be, I did recently adjust the air gap as the old one was getting weak.

With the crank bolt holding the clutch and rotor in place, how does the assembly have the freedom to move? I'm still confused how it works exactly.

Spaced it out with a .040mm gage as I don't have inch feeler gauges. Err on the wider side?

I may have misstated,it’s been years since I’ve ha d one apart but I think u r right,if all that gets bolted it can’t move.

I just looked at some parts,the rotor isn’t bolted down,it just sets there free,so it will move to the clutch and lock up when energized.