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notashandyasyou

john deere stx38 pto wont engage

notashandyasyou
12 years ago

hello folks. I inherited a JD STX38 yellow deck (manual transmission) when I bought my house in the country 6 months ago (I'm a former city slicker). this is a long, detailed post, but I figured that would only help - more information = better and easier to figure out what's wrong. it might even make you smile.

after jump starting the STX38 late last fall and getting some gas with fuel stabilizer added to run through it, it started up on the first turn this spring after I replaced the battery. Sweet! It was running fine, cutting fine - I annihilated my field (probably about 2 acres) with it 3 times this spring already.

Today I had an issue: I was cruising around the field, cutting, and I hit a rock - no big deal, this thing is solid. (I don't think the rock was the problem, but...) I also cut some relatively tall, thick grass - 18 inches high maybe, but the STX38 didn't stall out or anything - it cranked right through.

Ten minutes later, with the PTO engaged, suddenly the blades simply stopped, as did the loud sound that tells you that the PTO is cranking. I flipped the PTO off, then on - but when i flipped it on, there was no change in sound - it didn't roar to life. I turned the engine off and on and repeated with the PTO switch - nothing. The engine still ran fine, so I brought her back to the driveway and used my expertise to, well, all I could really do was stare at it - remember, I'm not as handy as you!

So, we have this wealth of information on the internet now, and I spent a few hours looking for solutions. I cleaned out all the grass that was on, under, and around the mower deck. I took apart the ignition/PTO switch case and cleaned the old grass/dust/hay/nests out of there. (I didn't pull any of the electrical wires out of their casings though) I removed the PTO ground bolt (behind the right front tire) and cleaned it with steel wool. I didn't remove the ground wires from the crimp they were in. Still, nothing happens when I flip the PTO switch up, to ON.

Now, one other test: I sat on the tractor with the engine off, but turned the key to "ON", and flipped the PTO switch up. I could hear the PTO mechanism "click," so I guess that's good in a way - it must be getting a signal, right? I read this: (http://forums2.gardenweb.com/forums/load/tractor/msg060934286991.html) that suggested checking the voltage flowing to the PTO - but I didn't do that because I lack the tools, I have a brand new battery, and the thing had just crapped out mid-run. This led someone I ran it by to think the problem wasn't electrical. He suggested I take apart the mower deck and look at the belts/pulleys - that maybe a belt came loose/off?

I can tell you that during my not-so-expert diagnosis, I did pull the belts a bit, and it definitely didn't look like anything was broken - ie, i could pull the belt and turn the pulleys - nothing unraveled in my hand and came out.

So, sorry for the long post, but I tried to include as many details as possible so that perhaps someone could suggest a next step. Now remember, I'm not as handy as you (remember Fletch, with the ball bearings and the sphitzer valves?) - but I'm capable of following instructions, provided they aren't "remove the PTO assembly and check the gearing," or things like that. please simplify for me! any guidance appreciated

other random info: I removed a mouse nest from under the engine hood. I don't think it's a mouse issue, since the tractor ran fine for 20 minutes before I had the problem today, and I didn't see any wires that were eaten thru.

random question: is there perhaps some sort of safety shear bolt or something under the mower blades, like in a snowblower?

many thanks...

Comments (32)

  • mownie
    12 years ago
    last modified: 7 years ago

    It's going to be a challenge for you without tools and lacking experience. If you are up for the challenge, you need to purchase a 12 volt test light (aka circuit tester light) and an inexpensive "multi-meter" that is capable of checking voltage, resistance (Ohms) and continuity. You may also want to invest in one of the many "primers" or DIY books to give you the basics of automotive electrical systems (and everything electric on tractors is "automotive".
    It should not take you but a few hours of study to get you to the point of being able to do the checks furnished by javert in the URL you provided.
    Even though you ARE "notashandyasyou", you were smart enough to move from the city and to find this forum........and you say you can follow instructions.
    The time and $ you put toward learning some new (to you) skills and acquiring the basic tools/instruments is one of the few "guaranteed investments" you can still make. Both the knowledge and the tools will serve you for the rest of your life.

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  • javert
    12 years ago
    last modified: 7 years ago

    notashandy, Once again Mownie has given great advice. You can get a good-enough multimeter (resistance and continuity meter) for $10 at most auto supply stores, Northern Tool, Harbor Freight, even Sears during a sale). A circuit-tester light (same sources) can be picked up for about $3. You might need a set of feeler gauges ($3-$5). Pick up an instruction book for the multimeter at a used book store for $5. These items (plus the knowledge to use them) will be invaluable for repairing/maintaining your equipment.

    Get the booklet that mownie offered. He sent it to me, and it's full of good material. It describes Warner PTOs, and your STX PTO was manufactured by Warner.

    As to your problem, I suspect that you've sheared the key that locks the pulley to the drive shaft within the PTO clutch. If you don't know what that is, it's a square bar of steel (probably about 1/8" sq and an inch or so long) that fits in a groove of the shaft and mates to another groove in the pulley assembly - if it is sheared, the shaft of the PTO will spin inside of the pulley but not propel it. The shear pin is a sort of "circuit breaker" to prevent internal engine damage by an abrupt stopping of the pulley - as in the blades hitting a rock. IF THAT'S THE PROBLEM, you don't need any of the eqpt listed in paragraph 1 to identify and repair it, as this would be a mechanical - not electrical - problem. How do you test for a sheared pin? You remove the pulley and look at the pin. DON'T remove the pulley in a dirt or grass area, as the pin is likely to fall out - at the very least, put a large sheet of cardboard under your work area.

    All that said, I'd do the electrical tests first, as you can do those without tearing into the PTO clutch.

    Good luck.

  • notashandyasyou
    Original Author
    12 years ago
    last modified: 7 years ago

    thanks for the advice, guys. one more question that you may have an obvious answer to - do people have a standard easy solution for getting underneath their equipment to muck around? ie, maybe use some 2x6 planks to drive it up onto an elevated bed of cinderblocks?

  • javert
    12 years ago
    last modified: 7 years ago

    For the front end I drive it up on car ramps. For the rear I chain-hoist it up about 10 inches, put the car ramps under the wheels and lower it onto the ramps.

    Do NOT hoist it with a comealong unless you block it up with something substantial.

  • notashandyasyou
    Original Author
    12 years ago
    last modified: 7 years ago

    ok guys - guess what - the solution may be simpler than I thought...

    I had someone slightly more knowledgeable than myself look at the mower today, and I was pointing him toward the parts I knew of. He didn't seem to be a tractor mechanics ninja, but he knew enough to say "shouldn't there be a belt here?"

    the mower drive belt was missing! aiyahhh!!! obviously, that's probably about the best case scenario for me, I'm assuming - as it should HOPEFULLY be a relatively easy fix. I looked for it in the grass where the mower had stopped mowing but couldn't find it. I'm sure it's an easy replacement via John Deere. one more question:

    so, I turned the mower on (with my wife sitting in the seat to make the safety work), and was somewhat surprised to see the PTO pulley spinning even when the PTO was in the "off" position... i expected that the pulley would be still, and when I flipped the PTO switch on, THEN it would start spinning... is this normal? so does the pulley always spin, but just not with enough tension to move the belt? and then when you engage the PTO it tightens the tension and kicks the mower mechanism pulley into motion?

    the instructions manual says i need to take the mower off the tractor to replace this belt - is that true? or can i just stretch it over the two pulleys?

    learning as i go, here...

  • mownie
    12 years ago
    last modified: 7 years ago

    It would be normal for the PTO clutch to rotate in a sympathetic fashion with the crankshaft if the belt was missing.
    You have the instruction manual? Good, follow the instructions it gives you. Trying to take shortcuts is not what you need to do.

  • notashandyasyou
    Original Author
    12 years ago
    last modified: 7 years ago

    amazingly, my project has stalled at what should have been the easiest part: removing the cap screw off the pulley on the mower blade mechanism so i can replace the belt. I followed the instructions in the manual that I have and removed the mower from the tractor, but the cap screw is stuck. bad. i mean, it's like it's welded! I picked up some Liquid Wrench and have been repeatedly spraying it since yesterday afternoon... Patience is my only option for now.

  • mownie
    12 years ago
    last modified: 7 years ago

    notas, could you possibly post a photo of the pulley and cap screw for clarification?

    Here is a link that might be useful: poster child

  • tomplum
    12 years ago
    last modified: 7 years ago

    rethink how that belt goes on. You don't need to pull that apart.

  • notashandyasyou
    Original Author
    12 years ago
    last modified: 7 years ago

    tomplum - hmmm.. i appreciate your hint/riddle... but i cannot figure out a way to get this belt on without removing the cap screw.

    mownie: here are some pictures (And thanks for the picture tutorial link!):

    {{gwi:323987}}

    {{gwi:323988}}

    {{gwi:323989}}

    as you can see, i've soaked the cap screw with 1) liquid plummer and 2 wd40 - repeatedly, since Saturday. NO movement at all...

    any ideas??!?!?

  • mownie
    12 years ago
    last modified: 7 years ago

    My take on this is you need to remove the bolt I have labled "YES". Then the arm marked with green arrow can be pivoted away, creating an open space where the new belt can be slipped over the top pulley.
    The bolt I captioned "NO" should not be disturbed for simple (yeah right! simple) belt replacement.
    If you could, I would like to see the view of the pulley and brackets taken from the other side.
    If the bracket/arm turns out to be a big "U", the the "NO" bolt becomes a "YES" bolt.
    And while we are on the subject of photos, be sure you take a few good pictures of how all the arms and spacers are stacked under th "YES bolt" so you can get that reassembled correctly.
    Now, it is entirely possible that the bracket (arm) I put the green arrow on, is a "U-shaped bracket" that has the bolt I call "NO" going all the way through to the bottom.
    That is why I would like to see the rest of that bracket/arm in a photo shot from the other side.

    {{gwi:323990}}

  • notashandyasyou
    Original Author
    12 years ago
    last modified: 7 years ago

    hi mownie - thanks for taking the time to diagram that out for me! i don't think that will work, though, as you can hopefully see in these pictures: as you suspected, it's a "U" shaped bracket, with the "no" bolt going through it all the way.

    {{gwi:323991}}

    {{gwi:323992}}

    you can also see my socket wrench I've been trying to use on this in the background of the second picture. I mean - is it possible i just need to twist it harder? i don't want to snap the thing off - i've been really torquing it.

  • buzzard_flats
    12 years ago
    last modified: 7 years ago

    Notso,

    Please put down the liquid plumber and take a step back, that may have already gotten into the bearings and made a mess of them as well as started to eat any aluminum parts it came in contact with.

    You need to get something like PB-Blaster at an autoparts store and spray that at the bottom of the bolts where the threads are. Is there a nut on the bottom of those bolts? If so the bolt may be treaded into the bottom of the bracket and the nut run up to lock it in place, loosining the nut by turning it clockwise as viewed from above would release the bolt to unscrew, otherwise forcing it could result in striping the bracket, shearing the bolt etc...

    Since you have the deck off, provided their is no lock nut under the bracket, I might suggest putting in in your trunk, truck bed etc and visiting your local friendly mechanic who could probably zip it out in 10 seconds with an impact wrench.

    If that is not an option then block the pulley to keep it from moving, use a box wrench and strike the box wrench with a hammer (aka caveman impact wrench) if you do the latter please wear safety glasses and gloves as wrenches have been known to shatter used that way.

    Lastly is their any chance that could be a lefthand thread and needs to be turned the other way to remove it? Sometimes on rotating parts the threads are lefthand for that reason, bicycle peddles, car lugnuts on old dodges etc come to mind.

  • notashandyasyou
    Original Author
    12 years ago
    last modified: 7 years ago

    buzzard_flats: thanks for the guidance. I had the PB Blaster in my hand when i bought the liquid wrench, but decided against the PB Blaster because their can boasted that their product would eat through a cup. I went for the less corrosive solution in the Liquid Wrench. also, there are no threads visible on any part of this.

    I don't think there is a lock nut at the bottom of the bolt - i think this is a "cap screw" which threads onto a fixed piece, through the pulley.

    i think my best bet is to do what you said about throwing the whole thing in my trunk and taking it to a mechanic.

    as for the possibility of the cap screw having "Reverse polarity" - or unscrewing clockwise - i've been trying to get an answer on that - i don't know. all i can tell you is that i tried turning it clockwise also, which didn't work either.

  • buzzard_flats
    12 years ago
    last modified: 7 years ago

    Notsohandy,

    Hey they say 'rust never sleeps' I don't think PB is corrosive just has more nasty solvents in it, sometimes nothing works short of the 'hot wrench' AKA oxy-acet torch to break things loose. Have you had a go at the other bolt? May be able to get that off and not have to drag the whole deck around or at least see what is going on under that U-shape bracket. Never know someone before you could have actualy welded that bolt to keep it from unscrewing.

  • notashandyasyou
    Original Author
    12 years ago
    last modified: 7 years ago

    i'm gonna seek help tomorrow from local handy-people... you're joking about the welding, but i'm starting to wonder!

  • buzzard_flats
    12 years ago
    last modified: 7 years ago

    Trust me, I have seen all sorts of 'fixes' so never discount that some previous owner may have put a dab of weld on something. May want to look into a hand impact driver like this:
    http://toolmonger.com/2009/01/30/craftsman-hand-impact-driver/

    You can get them for about $10 from harbor freight or a traveling tool show also.

    Saved by butt a few times with things like stuck bolts and they also work very well on philips screws/bolts that refuse to budge. Since they turn while they are being struck with a hammer they will not jump out of even half stripped screwheads like a standard screwdriver.

    I was not kidding about the 'hot wrench' just have to be careful and heat the parts fast to a dull red, then they usually unscrew without a fight. Something you just can't do with a propane torch as it takes too long to heat a small spot.

  • javert
    12 years ago
    last modified: 7 years ago

    The Word from the John Deere STX manual:

    "Disconnect the idler spring
    Remove cap screw (labelled NO, above), and sheave. Some models require idler (labelled YES) to be removed also.
    Remove belt

    Installation
    Install sheave and belt
    Tighten cap screw to specification
    Connect spring"

    All this, the manual says, can be done without removing the deck. Post all the numbers and markings, as well as the size of the cap screw, and I'll see if I can figure out what the specified torque is - the manual isn't easy to read on this issue.

    Use the P-Blaster. If still no go, buy, beg, borrow, bum, or steal an air hammer.

  • tomplum
    12 years ago
    last modified: 7 years ago

    On this version stack pulley a bolt does need to come apart. I stand corrected. Would I be incorrect to say that the lower bolt on the RH bracket if removed would allow the belt to shimmy in there? (The bracket that has the "yes" on mownies coolerific diagram)

  • mownie
    12 years ago
    last modified: 7 years ago

    That turned out to be sort of what I had expected. I'm glad everybody jumped in to help on this.
    I'm also glad notsomechanicky has a good camera finger.
    Those are some good shots.
    Yes, I have to agree the NO bolt is now a YES bolt.
    Kinda like when your kid brings home a kitten named Sam and you later find out it is Samantha.

  • notashandyasyou
    Original Author
    12 years ago
    last modified: 7 years ago

    javert - I believe my manual says the torque should be 70lb-ft when I reinstall it. that's my NEXT dilemma, if i ever get past the "uninstall" phase.

    thanks everyone for their help, advice and suggestions. - i will hopefully be able to get some help from some people with real tools in the near future.

  • notashandyasyou
    Original Author
    12 years ago
    last modified: 7 years ago

    ok folks - i'm BACK IN BUSINESS! a local handyman friend came over and got the cap screw off in 15 seconds using an electric socket driver (impact drill? impact wrench?), and holding the bottom nut with a wrench. he said i should have sprayed the bottom nut instead of the top cap screw.

    we then spent the next 45 minutes putting the mower back on the tractor - it was definitely a much easier job with 2 people.

    i may have tilted the blades somehow, or it may just be that my test run was done at the highest mowing height - i will figure that out this weekend, but i'm sure it's easily fixable.

    thanks all, for your help.

  • buzzard_flats
    12 years ago
    last modified: 7 years ago

    Good to hear the problem is solved, I had a gut feeling there was a nut at the bottom of that. One of the handy tools to have is a telescopic inspection mirror and a mini maglight to look under stuff where you can's see line of sight. I jokingly call mine a elephant dental mirror, about 2" dia with a handle that can be extended and swiveled, think it was about 10 bucks at the autoparts store.

    Some time in the future you may want to look into replacing the bearings in the spindles for the blades and the idler pully('s) probably someone here can give you the P/N of the bearings. I have had good luck with ordering bearings on-line either from ePay or Accurate bearing (1800-323-6548, Lynn) as they are less expensive than OEM or the worse choice hardware store bearings that are unsealed in one of those parts trays. I usually pay $3-4 per for what the local hardware wants $12 for and they come in sealed boxes.

  • notashandyasyou
    Original Author
    11 years ago
    last modified: 7 years ago

    Hey folks, so I'm posting this follow up in my original thread because I think I have a related problem.

    Last year, I replaced the PTO drive belt and the mower blade drive belts on my inherited JD STX 38 Yellow Deck.

    Today I took the mower out (NOT the first time this season) and had some serious issues. First of all, the grass is tall - 18-24 inches. I had the mower height set to the tallest height. The grass may have also been slightly damp - although not wet.

    I was able to cut basically one path, then I realized that although the PTO was engaged, the blades weren't cutting the grass. I was going at the slowest speed (first gear) and even tried cutting using only 1/2 of the mower deck width at a time - no help.

    I took the mower back to my driveway, cleared out lots of old clumped grass from the blades, and started the mower and the PTO. The blades were definitely turning. I turned off the mower again, and noticed that the PTO drive belt is looking terrible - it's all pitted and slack - it's not tight around the PTO shaft!

    So, my theory is this: the PTO drive belt is shot again (Although not broken yet) - so the blade spin when I'm not trying to cut anything, but when I come in contact with any sort of grass of substance, the slack belt is "slipping" and resulting in the blades not cutting?

    Does this make sense? Solution: replace the belt AGAIN????

    A few more things to note: 1) I tried cutting shorter grass and drier grass and had very little luck. 2) why would my PTO drive belt, just replaced a year ago, be so shredded already? That's worrisome...

    any advice would be appreciated.

    thanks.

  • chmst1999
    11 years ago
    last modified: 7 years ago

    hello all. I have a related problem. I replaced my belt when this same problem occurred, and it seemed to cut fine. However, it seems like the belt is loose. Now, when I pull up on the switch to engage the deck, it haphazardly works. As I'm cutting, the blades stop and then if I stop for a moment, they start again. How do I tighten the belt?

  • tomplum
    11 years ago
    last modified: 7 years ago

    chmst, I assume that the tensioner is seized and likely needs to be freed up to work.

  • jdfix
    10 years ago
    last modified: 7 years ago

    Yeah - I'm new to this - Forums and tractors. To mownie - Can I get in on the PDF for the PTO ? My PTO switch was "incnsistent" is starting and not starting. The PTO no longer works.... Thanks

  • mownie
    10 years ago
    last modified: 7 years ago

    jdfix, I will be glad to provide a copy of the PDF manual......but you need to e-mail me first so I can attach it to the "reply". This PDF covers ONLY the actual PTO electric clutch. It gives instructions for testing and adjusting the clutch. It does not give any information about tractor wiring or tractor wiring diagrams.
    I checked your forum profile and saw that you did not include your e-mail address. So you need to find mine and e-mail me.

  • airjose
    10 years ago
    last modified: 7 years ago

    Well, I have the same problem. I found out that the deck pulleys must be checked. The small long screw goes into a long sleeve and bushings thru the deck attached to a nut. All must be free and greased (lubricated) and replaced if they are bad. I had to cut mine and replaced them all as they were rusted and frozen. Now my PTO does not works. My mower was left outside by the previous owner without starting for 6 months. (mownie please send me a copy of the pdf manual if possible) The PTO is not locked but will not engage.

  • maxx4
    9 years ago
    last modified: 7 years ago

    Was posting cause I had the same problem this weekend hit are piece of wood and blades stopped. Thought it was the belt cause it was really loose and wasn't the clucth cause with mower key turned but not started I heard the clutch click any way it was the tension spring on ejection side of deck. It had spun and made the belt loose. Easy fix best thing to do is call your local dealer and talk to parts and they will give you some tips on what to check. With their suggestions and looking at pictures of what a deck should look like I found the solution.

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