1988 John Deere Hydro 175 - Engine stalls when I engage the blades

[SquatchLife]

I had that model, served me well for years. If all spins freely, I would check the seat switch. That is the only safety switch for the mower deck. Check alignment of brackets/pullies, as well as bolt tension as to why it's tossing the belt.

Seat safety switch still works perfect With and without the bypass.
However, I still cannot get the blades to engage. The lawnmower still shuts off as soon as I go to engage them like I’ve turned off the key.

 

[alexpops]

If you don't attach the belt, does the tractor cut-off when you engage the PTO for the mower?
Maybe a short in the Mower PTO clutch? or the wiring?

 

[SquatchLife]

Seat safety switch still works perfect With and without the bypass.
However, I still cannot get the blades to engage. The lawnmower still shuts off as soon as I go to engage them like

If you don't attach the belt, does the tractor cut-off when you engage the PTO for the mower?
Maybe a short in the Mower PTO clutch? or the wiring?

I just removed the belt and tried again. It turns off when I go to engage the blades.
So you’re saying that means it’s the PTO or wiring?

Where would you start?

 

[EddieWalker]

My Scag zero turn throws belts too. I think I've figure it out, but it's too early in the mowing season to be sure. It only happens when I first start to mow with it, but once it's been mowing for a while, it works properly.

New blades made it better, but didn't fix the problem.

I changed the type of grease that I was using on the spindles, and that helped, but it still happened. I bought new belts and that helped, but it still happened. I bought new springs that control the tension, and it hasn't happened since.

In my case, I think that everything was causing it, and by just replacing one thing, it got better, but it didn't completely solve the problem.

If it happens again, I'm thinking that I need to find a soft start switch to turn on the PTO. I don't even know if such a thing exists, but that's what I think I might need.

 

[alexpops]

trace the wire back & feel for breaks in hot side insulation especially against anything that might chafe through. If you don't find wire problems, disconnect the PTO connection & try an OHMmeter between the two plugs on the pto side, each plug and the pto housing. Or pull the PTO off the crank shaft & bench test it. Just make sure if there are any shims/washers you put things back together in the same order.

 

[alexpops]

If the clutch is bad ... here's some amazon alts to JD parts. Unfortunately, it doubles the cost of your tractor if it's a bad clutch.

Amazon.com : mower pto clutch jd 175

 

[oldnslo]

If you have an ohm meter and can trace the wires from seat switch to ignition circuit I would disconnect both ends of the wires and check for continuity in the wire to see if wire is broken and then to ground to see if rubbed bare someplace and shorting out.

Not sure if that model has an easy way of disconnecting the kill wire on ignition. If yes pull that and see if engine stays running. If it does then you know there is an electrical problem somewhere.

 

[alexpops]

To rule out the switch, you could use any cheap switch to replace & test.

 

[oldnslo]

trace the wire back & feel for breaks in hot side insulation especially against anything that might chafe through. If you don't find wire problems, disconnect the PTO connection & try an OHMmeter between the two plugs on the pto side, each plug and the pto housing. Or pull the PTO off the crank shaft & bench test it. Just make sure if there are any shims/washers you put things back together in the same order.

Wouldn’t a bad clutch either not engage or blow a fuse vs killing the ignition circuit?

 

[SquatchLife]

If the clutch is bad ... here's some amazon alts to JD parts. Unfortunately, it doubles the cost of your tractor if it's a bad clutch.

Amazon.com : mower pto clutch jd 175

I think I’ll start with replacing the dash switch and see if that fixes the issue. I don’t have a way to bench test my clutch or test the wiring.

While the mower is off, how much place should the clutch have?