Blades won't turn on all of the sudden. 1993 John Deere 320 (PTO issue)

[beenthere]

I thought the shaft that comes down from the motor (drive shaft?) has an upper pulley with a belt for driving and a lower pulley that has the PTO. I'm only assuming this.

Looking at the schematic showing the Warner clutch, am thinking you are correct and that lower pulley is key #2.

Dealer (parts) will have electrical schematics, confirmation of which clutch via s/n, and which parts are nla (prolly the ones you may want). But am also thinking what Rick suggests.. need to adjust the air gap.

Sure are low hours on your 320. Well worth getting running again.

 

[Zebrafive]

I've already searched the forum and read a few threads, some were never even resolved (or the OP didn't return to share what went wrong) So I'm starting my own with intentions of documenting all results for future reference.

Yesterday my mower blades just stopped turning on when I flip the PTO switch.

Here is what i've done....

I get about 3 ohms when I test the PTO clutch itself....from what the internet says, that means its good.

If I sit on the seat, start the engine and stand up, the mower continues to run. If I sit on the seat engage the PTO and stand up from the seat, the engine shuts off. So I assume the safety switch is functioning properly.

I tried to test the switch with my ohm meter, but there are like 5 prongs/probes/whatever on it and I'm not sure which one is which.....If i sit on the mower, turn the key to the on position, and engage the PTO i distinctively hear the PTO clutch "click" on.

I'm not sure what to do next....I read something about adjusting the airgap or perhaps something mechanical/physical is wrong with the clutch. Please advise oh yeah, and, thanks for having me again

To Test the PTO switch:

The five "prongs" looking at it from the REAR;
Top row, from left to right, first is "D" second is "E"
Next row, from left to right, first is "C" second is "B"
Last row, one remaining "prong" is "A"
To test with an OHM meter:
KEY OFF!!!
PTO Switch OFF: You should have continuity ONLY between (B and E) and (C and D)
PTO Switch ON: You should have continuity ONLY between (A and B)
Be sure your meter is on OHMS and the connectors are removed from the switch when you test.

 

[Zebrafive]

The mower has about 600 hours on it....yes, 600 hours. I'm not sure if the upper half of the clutch moves, but I assume it does because its connected to the drive belt, correct? The mower will still drive foward/reverse. If I start the engine, and engage the PTO, the lower spindle (one that operates the deck) does not spin....note: I currently have the deck removed and set aside.

edit: I read online that the PTO clutchs usually last about 500-800 hours...I didnt mention my mowers hours because I didnt want a fast response of "Just replace it" ya know what i mean...

the deck stopped working yesterday...it hasnt worked at all since....so i cant really attest to the hot/cold question

There is a pulley above the PTO clutch. This has a belt to the trans axle. It is not part of the PTO clutch. It drives the trans axle with a belt at all times the engine is running.

 

[Zebrafive]

I thought the shaft that comes down from the motor (drive shaft?) has an upper pulley with a belt for driving and a lower pulley that has the PTO. I'm only assuming this.



Forgive me, but why do i need to take my serial number to the dealer? to find out more about which electric clutch I have?



I removed the deck and the deck seems to move freely by hand




When I get home from work today i'll try to do some more research and i'll report back

You are correct upper pulley on engine shaft is to drive the trans axle. Lower pulley is to drive the deck.

The reason to determine which clutch you have is each has a different air gap spec.

 

[Zebrafive]

I would check the air gap. This is done KEY OFF I am guessing you have the Warner clutch. Air gap spec is 0.015-0.025 inch.
You will see three nuts that secure a triangle shaped piece. each will have a spring on the stud above the triangle piece.
Below the triangle piece you will see two round discs.
Check the gap between these two discs with a feller gauge. Use a 0.020 in feeler Check at each of the three nuts. adjust as required.
Nuts and springs are #3 in the drawing

 

[Zebrafive]

Final test you can do is check for voltage to the PTO clutch.
KEY ON. ENGINE NOT RUNNING!!!!!!!!!!!!!!!!!
PTO Switch ON
Seat Switch either someone ON the seat, OR the two wires to the seat switch jumpered together.
Blue wire to clutch should have 12 volts.

Black wires ground.
You can test the ground by meter on volts connected red lead to battery positive terminal, black lead to black wire. You should see 12 volts on the meter. KEY and PTO switch OFF.

 

[nate81]

The reason to determine which clutch you have is each has a different air gap spec.

I called my local john deere and he had no idea lol....he said it could be warner or ogura....but i guess it doesnt matter, because that .pdf says .015 inch.....i found that .pdf on this site....not sure if its even remotely related to what i have.

I checked the voltage at the blue wire like you said in your last post and the switch seems to be ok. I also checked the ground and it was showing 11.2 or so...so i'm assuming thats also ok. I'm going to check the airgap to see where its at right now and will adjust it to .015" and i'll report back

 

[nate81]

The gap seems to be ok. I actually loosened it just a bit. I cranked the mower, sat in the seat....turn on the pto and it clicks but i dont see the pulley rotating. But my ohm meter says the clutch is good? I'm getting confused now....

 

[nate81]

Added a picture, because everyone loves pictures

i had the hood off because I have a slight oil leak....i replaced one of the valve cover gaskets yesterday, i'm hoping that fixes that issue. We'll soon find out, something makes me think its leaking oil at the exhaust manifold....but i hope i'm wrong

 

[nate81]

Ok, well, i tightened the airgap up to .015....and now the pto clutch works without the deck on of course.....

sooooo...i let my son drive the mower for his first time....and all of the sudden the drive belt shreds to a thousand peices while in the driveway!!! what!? is that just sheer coincidence? I will admit i let him drive it around the yard a few times at low rpm and a slow speed.....could that have done it? that doesnt even make sense though....crap. one problem fixed, and another immediately arises? what gives??