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Discussion Starter #1
Hi guys, gave my in law a real nice JD STX black deck. Ran good . They mowed last night , told me big flame came out pipe, some smoke and death?!?
Went dowmn and checked it wasn't seized. Went to start it, and it runs with a loud non rod like knock? We towed it home and oil is good ( may have been added after fact!? ) The sound is there when cranking it over and at all throttle levels. Might this be the valve seat ( s ) loose? I will take pictures when we get to take head off. We will check engine bolts and normal stuff first! Any ideas with the little info I have at moment!
 

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Its hard to say for sure, but my first suspicion is valve trouble. If a valve suddenly stuck or a seat dropped, the engine could have flamed out, and it definately won't run again until it gets fixed. That loud clunk could be a loose seat or valve head coming into contact with the piston.

First thing Id do is pop the valve cover and have a look inside. Look for anything out of place...one valve stem sitting lower than the other, bent pushrod (s), damage or breaks to a rocker arm...

If the valves are all in order, do a cylinder leakdown test. Massive leakage = head has to come off to investigate.

If the engine passes or at least scrapes by a cylinder leakdown test, the damage is probably somewhere in the bottom end. Likely a rod.

Though before assuming anything is broken, bear in mind this engine has hydraulic valve lifters, and a bad lifter will tick and clatter at all engine speeds. They don't usually make any noise during cranking, so your problem is probably more severe if its a heavy clunk all the time, but it could just be a bad lifter. These Command engines require 10w-30 oil for the lifters to perform correctly.
 

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Discussion Starter #3
Hi Poke, we ran 10W30 already. We got it in 9/15/12 last year and restored it. Got it done in January. My sister wanted it ,so off it went to mow in March to their house down the road. Mowed maybe three four times, dead? Guess the engine had a problem we didn't see/ hear! We only cleaned carb on it and oil change of course with new filter. Thank God we didn't sell it, or mad customer for sure! My sister is easy, I finished mowing for them and will test mow some tractors there to appease them!
 

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Just wondering, did this mower sit for any length of time with fuel in the tank? This gasoline we have now is so bad that I've seen a few engines that will run on this old fuel for a little while, only to stick an intake valve when they get hot. That may have been what happened to the Deere. Old ethanol-blended gas will gum up an intake tract quickly, even if it passes through the carburetor without problems.
 

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Discussion Starter #5
Hi Poke, no this was a total restore, tank was removed and cleaned. New fuel line ,filter ,shutoff. It was done for resell. My sister and in law saw and fell in love with it! Took care of resell! :( LOL
This machine sat under a deck for at least three years, was nicknamed arachnophobia due to the size of the spiders in it! It had hundreds of various size spiders in it, on it ,under it!!! It ran well, but was done in winter , so this is first real tests. In law let grass go high of course, because they had no fuel? My sister and him are disabled, so little money . We help best we can. Guess they should have kept the old Bolens I gave them, real nice machine that one was, low hours, garage kept!
 

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Looks like you're going to need to check it out firsthand to get a definate answer about what actually went wrong, but Im still leaning towards valve problems. Hope its something simple for ya. I hate fixing one and having it come back a little while later with more problems. Doesn't matter what went wrong....it still gets frustrating, and makes me look bad.
 

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Discussion Starter #7
Hi Poke, hoping your right! I can get a head easy. finding a engine is also not terrible. Just want to find out what happened now! Curious about the cause! I know what you mean. We do this as a hooby only. Had a few return or customer come back to complain. Dad takes it personal, his name on machine! I feel bad for him! He is older now,so he might forget to do something , then it makes machine fail. Thank God this one stayed in family. My sister and in law are poor, so I wind up giving them cars, now tractors. At least they are ours still, just off property! :)
 

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Discussion Starter #8
Well guys found out our issue! Thank God it wasn't real bad. We cleaned up damage. Buttoned it up tonight. Will start it tomorrow! Cranked it and nice and quiet!


Guess the choke bolt came out and it must have gotten stuck in valve for the flame out pipe!


 

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BOSS
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hey i have a stx 38 black deck
i only am going to rob the engine off of it if you want it for part pm me
 

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Well guys found out our issue! Thank God it wasn't real bad. We cleaned up damage. Buttoned it up tonight. Will start it tomorrow! Cranked it and nice and quiet!


Guess the choke bolt came out and it must have gotten stuck in valve for the flame out pipe!


Got lucky there! Just be SURE to Loctite those screws down tight once you're done. Don't want it happening again. I see this problem from time-to-time, mainly on Briggs and Stratton engines, and it is always those pesky little screws which come loose. Go figure...
 

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Thanks Poke and LTG! Thank God it didn't! I found another issue with it though, the Stator must be dead. I ran it with PTO on for bit, came back and turned it off. Went to restart, nothing! Battery was dead. Check charging system with multimeter, 12v. Changed the voltage regulator with spare, same. Checked with test light ,the charge leg dead. Oh well! Will troubleshoot it another day. Told in law to charge battery, told me he was!? Guess we could not troubleshoot it too good in winter?! :)
 

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Thanks Poke and LTG! Thank God it didn't! I found another issue with it though, the Stator must be dead. I ran it with PTO on for bit, came back and turned it off. Went to restart, nothing! Battery was dead. Check charging system with multimeter, 12v. Changed the voltage regulator with spare, same. Checked with test light ,the charge leg dead. Oh well! Will troubleshoot it another day. Told in law to charge battery, told me he was!? Guess we could not troubleshoot it too good in winter?! :)
If the charge leg (purple wire) has no voltage present with the key on, your stator and regulator aren't the problem. At least not yet. You probably have a bad connection, ignition switch connection, or a bad switch itself. That mower is wired up so that the ignition switch removes power from the regulator when the key is off, and restores power when you turn the key on. With the key on, you should have battery voltage present at the center post of the regulator.

Start by pulling apart the compound plug which connects the engine to the tractor's wiring harness. These plugs are notorious for filling with dirt/corrosion and rattling loose. A bad connection here, especially at the stator feed wire, will quickly arc and burn the contacts. Fix as necessary.

If the connection is OK here, time to check the keyswitch. Since the keyswitch is on the rear fender on that model, its easy to pop the switch loose and have a look behind it. If all connections are good here, chances are you'll need a new ignition switch.

If you restore power to the stator and still no charge, then start checkong the stator.
 

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Discussion Starter #14
Thanks Poke, I'll check it out next time I can get hold of tractor. They are using it now.
 

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Discussion Starter #15
Well just picked it up to find out issue. Poke, you are correct, no voltage in center and far right wires. The Stator wire on far left is bright on test light. All wires at voltage regulator BTW!
Will check out better when able! Gave them another STX 38 yellow deck we just got done!
 

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Discussion Starter #16
I found the problem, a foolish mistake on my part. I found that I put the charge wire on the start side of solenoid! LOL I only had power when cranking.
I switch wires and now charge system has 14.5 volts!! Thanks guys for all the help! Returned it to Brother in law this morning and got my yellow deck back before he ruined it!
 
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