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

[SquatchLife]

Hey all,

Literally bought the tractor yesterday for $150. It was running and mowing very well when I bought it. Fast forward 24 hours and it mowed for about 10 minutes before it threw the blade belt. Got it back on and mowed for another 10 minutes when it threw the belt again. Got it back on, went to engage the blades and the mower stalled. I checked the belt to see if it was too tight and it spins freely by hand. I checked the blades themselves and they spin freely by hand. Checked the blade engagement toggle in the dash and one of the connectors was not plugged in. So I unplugged it, cleaned it up, got all the connectors plugged in and lined up and the mower still stalls when I try to engage the blades.

Should I start with replacing the toggle switch or should I look elsewhere on the mower first? Or should I be looking somewhere else entirely?

 

[oldnslo]

Is the engine stalling like under load or like you turned the key off?

I would investigate why it is throwing the blade belt. It could point you towards a problem also.

 

[SquatchLife]

It’s as if I turn the key to the off position.

I will continue to look into why it’s throwing the belt. At the moment I haven’t the slightest idea. It does look like there is a minor wave in the front pulley but not enough for the belt to throw.

 

[Richard001]

Is this what your mower deck looks like ?

If so, then I would start by looking at the support that holds the idler tenson pully and the pulley bearings. I'm guessing that they are worn and allowing the pully not to be aligned with the belt path.

Also make sure that the tension spring is doing it's job.

Richard

 

[SquatchLife]

Is this what your mower deck looks like ?


View attachment 3217737

If so, then I would start by looking at the support that holds the idler tenson pully and the pulley bearings. I'm guessing that they are worn and allowing the pully not to be aligned with the belt path.

Also make sure that the tension spring is doing it's job.

Richard

That is my mower deck. For clarification it’s actually the top pulley at the bottom of that picture that keeps throwing the belt

 

[alexpops]

when it's hooked up & attached to the tractor, check the alignment, tension, routing & clearances between the pto clutch & that pulley. Could be the power belt is loose enough to grab somewhere & stall the engine. Finally, does it look like that pulley has been removed by previous owner & put back upside down or with missing shims? Also, I'd check for any bends/flex/loose bolts on the tensioning brackets/pulleys/etc. between the pto and that deck pulley. Could be the previous owner clipped a tree/stump/rock & bent/loosened/broke something.

 

[oldnslo]

If it is like turned the key off I would suspect a safety switch is the culprit. I am not sure how many switches there are on that tractor though.

Does it have a switch on the seat for operator presence? If yes I would check that and then look for more. Hopefully someone more familiar with that model will chime in with other things to check.

 

[Mtsoxfan]

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.

 

[SquatchLife]

I will check that first thing in the morning and bypass it then try again. Thank you!

 

[Mtsoxfan]

You didn't mention, but even a bit of oil on belt will do same thing. My NH TC29D has a oil leak, it shredded a belt, tossed the replacement before I installed an oil shield.

 

[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

www.amazon.com

 

[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

www.amazon.com

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?