JD Hyrdo 175 engine dies when PTO engaged

Jeannine · Jul 9, 2017

The hubby bought me a pretty nice looking JD Hydro 175. Runs like a champ, purrs like a kitten. There are a few mechanical problems I'm working on, but the Biggest problem is, engaging the PTO for the mower blades, kills the engine....this is an issue since I need it to mow the lawn, which keeps growing by the minute. I know it's not the seat safety switch as that has already been cheated. The blades move freely by hand.

I'm not a mechanic, but I'm teachable and will try tasks above my pay grade :lol:

kcred · Jul 9, 2017

You need to look at the operating manual for safety switches that are shutting down the engine when you engage the blades.
the seat switch is one ,backing up is another .

kcm.MN · Jul 9, 2017

That's where I would start also. Most likely the seat switch, IMO.

Jeannine · Jul 9, 2017

(quoted from post at 09:54:04 07/09/17) You need to look at the operating manual for safety switches that are shutting down the engine when you engage the blades.
the seat switch is one ,backing up is another .

I have the operator's manual, but it doesn't mention the existence of a RIO(?) switch. I'll poke around to see if I can find some documentation / wiring schematic for this model. The manual I have is for the 170, 175, 180, and 185 lawn tractors. It's pretty vague.

504 · Jul 9, 2017

Do you have the brake on? The blades shut off when you use the brake on a lot of JD.

Jeannine · Jul 9, 2017

No, the brake is not on.

Also, there is no RIO switch on a Hydro 175.

I found the service manual for the 175 and I'm plowing through it to find clues..it's sort of gibberish to me since I'm not a mechanic.

I also found another reference to my problem on another forum. One reply involved replacing the PTO coil. Not sure what that is exactly.

Stumpguy · Jul 9, 2017

I don't know about the Hydro 175, but I have a 1995 LX188 and a 1995 345. The 188 has to be run around the yard for at least 5 minutes before the blades engage. if I
engage before the warm up, the engine dies.

old · Jul 9, 2017

As per what a friend of mine says on the JD lawn mowers like your a bad PTO switch will cause that to happen. This guy works on lawn mowers and has for the past 30 plus years I have known him

Jeannine · Jul 9, 2017

(quoted from post at 13:12:41 07/09/17) I don't know about the Hydro 175, but I have a 1995 LX188 and a 1995 345. The 188 has to be run around the yard for at least 5 minutes before the blades engage. if I
engage before the warm up, the engine dies.

I'd be delighted to run it around the yard for at least 5 mins, but I can't....that's another one of my little problems. The front wheels are locked in a right-turn, so the best I can do is donuts. :lol: Working on freeing them up...involves a torch and a 3lb hammer. I'm not sure exactly how long I've let it warm up before attempting to engage the mower, but once I have the other problem fixed, I'll give the 5-min runaround the yard thing a go.

Jeannine · Jul 9, 2017

(quoted from post at 14:10:15 07/09/17) As per what a friend of mine says on the JD lawn mowers like yours a bad PTO switch will cause that to happen. This guy works on lawn mowers and has for the past 30 plus years I have known him

I'd considered that after watching some You-Tube videos loosely related to my problem, and it certainly seems a lot less onerous than some of the possibilities (like a new clutch). Thank your friend for me...we'll give that a whirl as soon as I can get one ordered and delivered. In the meantime, it's back to the hammer and torch :arrow:

David G · Jul 10, 2017

I would pull the wire off the PTO clutch so it does not energize, that will tell you if the kill circuit is doing it.

Jeannine · Jul 10, 2017

(quoted from post at 12:55:51 07/10/17) I would pull the wire off the PTO clutch so it does not energize, that will tell you if the kill circuit is doing it.

We'll give that a try as well...just as soon as I can open the hood again. I have the front end jacked up right now in hopes of freeing up the front wheel spindles...it would appear someone did not grease the fittings regularly, and they are pretty well stuck. When I heated them up with a regular Bernzomatic torch, no grease oozed out...probably not a good sign. With the front end jacked up in front of the muffler guard, I can't lift the hood and access the electrical components located under the dash shroud.

Texasmark1 · Jul 11, 2017

Have you run the rpms up before engaging? The lower the hp and wider the deck, the more torque it takes to get the deck moving. I just
bought a 61" mower and it has to be above half throttle or it will kill the engine and it's new; dealer told me to expect it.

kcm.MN · Jul 11, 2017

Mark brings up an interesting thought, and one I "should" have considered earlier. Do your deck spindles have zerks on them? If so, have they been lubed? If they haven't been lubed or if there are no zerks, there's a chance the spindle bearings are going out, which would put more strain on the engine when engaging the deck. If no zerks, then do yourself a favor and replace the spindles anyway, or at least have replacements on hand for when (not if!) they fail.

Another possibility (but sounds like you covered this part) is whether the deck brake is fully disengaging.

Texasmark1 · Jul 12, 2017

Along your train of thought, with the deck disengaged making for a loose belt, a quick spin of the sheaves would answer the bearing
integrity question and the idler pulley(s) too which are points to consider. With the engine off and engaging the deck would be a quick
visual check to see if the brake pads disengaged. Both good points too.

Jeannine · Jul 14, 2017

(quoted from post at 06:48:34 07/11/17) Have you run the rpms up before engaging? The lower the hp and wider the deck, the more torque it takes to get the deck moving. I just
bought a 61" mower and it has to be above half throttle or it will kill the engine and it's new; dealer told me to expect it.

When I last tried it, I did have the rpms pretty high. . . tried it high, med, and low.

Haven't had a chance to work on it much this week, since I've been sick. Will get back at it again this weekend.

W_B · Jul 14, 2017

Might check for a short in the wire(s) going to the PTO mechanism, if you have one the short will kill the engine.

Jeannine · Jul 14, 2017

(quoted from post at 05:51:24 07/14/17) Might check for a short in the wire(s) going to the PTO mechanism, if you have one the short will kill the engine.

Will do.

I have given up on trying to free up the front spindles, and purchased a new-to-me front axle steering assembly with spindles AND 2 rear wheels with tires (w/out dry rot) on eBay for $105 !!!!! including shipping

They are scheduled to arrive late next week, so your and everyone else's suggestions will be tried after the front end is fixed and I can access the stuff under the hood. You all have been wonderful. I'll let you know how we make out.

caseman-d · Jul 23, 2017

Drive belt isn't stuck to the clutch pulley?Is it possible that the clutch is froze up.
caseman-d

Jeannine · Jul 24, 2017

Parts have arrived, but we haven't had a chance to install yet. Will let you all know how we make out with the suggestions once we get the front axle/spindles replaced.

Jeannine · Oct 15, 2017

(quoted from post at 04:02:22 07/24/17) Parts have arrived, but we haven't had a chance to install yet. Will let you all know how we make out with the suggestions once we get the front axle/spindles replaced.

It's been a long time since I was here....been real busy with other stuff, but I'm happy to report I got the front axle installed, and bought a new PTO switch (just in case). Went to start the machine, and it won't catch. It's getting gas and turns over nicely, but no catch. PTO switch works since when it's engaged, the engine doesn't do anything. Found out there was no spark. Bought a new ignitor module....no help. Bought a new coil...no help. Took apart the flywheel assembly...nothing looks bad and the little pin in the shaft is good. Juice is getting to the coil, but no spark. I'm stumped.

Jeannine · Oct 15, 2017

(quoted from post at 07:23:44 10/15/17) [It's been a long time since I was here....been real busy with other stuff, but I'm happy to report I got the front axle installed, and bought a new PTO switch (just in case). Went to start the machine, and it won't catch. It's getting gas and turns over nicely, but no catch. PTO switch works since when it's engaged, the engine doesn't do anything. Found out there was no spark. Bought a new ignitor module....no help. Bought a new coil...no help. Took apart the flywheel assembly...nothing looks bad and the little pin in the shaft is good. Juice is getting to the coil, but no spark. I'm stumped.

OK...so I went out and fiddled with it some more. Put a new, correct spark plug in...nothing. On a whim, I changed out the new ignitor module with the old ignitor module because the spade connector on the wire from the coil didn't fit quite right on the new one. Turned the key, and voila! It started up and caught. And. I could engage the PTO without killing the engine.

Problem solved, right? Kinda. Now it won't shut off unless I pull the spade connector off the ignitor module. I haven't monkeyed with any of the wires since before when it ran before it wouldn't run. I don't understand. Anyone got any ideas?

Oh, and before I end, it would appear the brake doesn't work quite right....even with it fully depressed, the tractor still moves...not fast, but the brake isn't holding it stationary. :? :?

JD Hyrdo 175 engine dies when PTO engaged

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