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K321 Compression Issue?

2511 Views 67 Replies 10 Participants Last post by  CorkGuy94
1986 JD 214 / K321

Bought used with a rebuilt engine

Approximately 300 hours on rebuilt engine

2020 Service @ dealer: Replaced Rear Sheave / Replaced deck and power belts / Lubed deck bushings / sharpened blades / Oil change / Adjusted deck height. Minor oil leak from bottom but not significant.

Mid 2021 Performance issue: Runs with no issues without PTO engaged. Engage PTO, and after 10 minutes, engine sputters, engine shakes, engine stalls, and engine recovered when choked but stalled immediately after choke removed. A bit of oil popping from oil tube.

Checked for spark, and when this issue occurs, spark remains constant.

Changed Capacitor, changed coil, changed plug (which had been the incorrect plug), changed points which were only 5 years old, changed plug wire..

Same issues after above was performed.

Early 2022: Changed carburetor.

After carburetor change, mower ran well with PTO engaged, for about 40 minutes and then engine sputters, engine shakes, engine stalls, and engine recovered if choked but stalls immediately after choke removed. A bit of oil popping from oil tube. A slight bit of smoke from exhaust. Engine still starts and runs well without PTO engaged.

Shop where I bought the JD thinks it may be a compression issue.

How do I check compression on a K321 which has an Auto Compression Release Mechanism?

August 29, 2022 EDIT:

FWIW, I just ran a compression check, with a compression check tool. 120 PSI, 5 times. I don't have a compression problem.

Might this be a fuel pump issue, since I have gone from 10 minute run time to 40+ minute run time after installing a new carb?
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Edit: the pto must be engaged, and you must remove the mower deck belt from the clutch. Also, you want to turn the clutch clockwise.

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#5??? Choke wide open implies not engaged at all...not fully engaged.
IME at best you will get inconsistent readings and risk damaging your arm/shoulder. When I tried this on a 214 rehab some years ago, I did the thumb over spark plug hole test instead and checked valves (ok) and head gasket integrity instead. Then decarboned the head and piston just in case. Quit stumbling after that, but mine wasn't bad enough to choke/kill the engine with PTO engaged...so may not be a valid comparison. If you do the comp test, rely on a set of young arms/shoulders!
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I would also be concerned with the gas you are using. A small amount of moisture in gas will cause pump gas with alcohol to separate. It will collect in bowl of carburetor and engine will not run on it unless the choke is pulled in most cases. If you wash the machine, it is easy to get a small amount in the fuel cap vent. One should always cover it during washes. You can drain some gas into a clear jar to see what you have and if it’s separating. I don’t know if I would put much faith in the compression test with the ACR on these engines. Oil consumption is a better sign of cylinder condition. A head gasket is pretty cheap and one gets to look at cylinder, piston top, and valves as well as a good decarboning while in there. Good luck with the hunt for your problem.
I would also be concerned with the gas you are using. A small amount of moisture in gas will cause pump gas with alcohol to separate. It will collect in bowl of carburetor and engine will not run on it unless the choke is pulled in most cases. If you wash the machine, it is easy to get a small amount in the fuel cap vent. One should always cover it during washes. You can drain some gas into a clear jar to see what you have and if it’s separating. I don’t know if I would put much faith in the compression test with the ACR on these engines. Oil consumption is a better sign of cylinder condition. A head gasket is pretty cheap and one gets to look at cylinder, piston top, and valves as well as a good decarboning while in there. Good luck with the hunt for your problem.
Fuel is new, I don'twash the engine or the body, doesn't use oil
Edit: the pto must be engaged, and you must remove the mower deck belt from the clutch. Also, you want to turn the clutch clockwise.

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Where does one find the PTO sheave, and how does anyone reach 1000 rpm by pulling a rope with shoulder and arm?
The PTO sheave is what engages to the crank, where the deck belt goes on/rides. And if it's got decent compression, you'll be hard pressed to hit 1000 rpm jerking it clockwise with a rope...even with the plug out. Be careful of the rope knot, they sting.
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Turning the engine backwards is to make the compression release not release said compression. 1000 rpm doesn't necessarily need to be achived.

This is the PTO sheave
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If your tractor has an electric clutch as shown above, check the resistance of the clutch coil. When the coil starts to go bad, it draws more current. The ignition is affected and the engine will stumble and die. Does your engine recover quickly if the PTO is disengaged quickly?
Disregard if yours has a manual clutch.

tommyhawk
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If your tractor has an electric clutch as shown above, check the resistance of the clutch coil. When the coil starts to go bad, it draws more current. The ignition is affected and the engine will stumble and die. Does your engine recover quickly if the PTO is disengaged quickly?
Disregard if yours has a manual clutch.

tommyhawk
It recovers immediately if I disengage the PTO

How do I do this? "check the resistance of the clutch coil"

The only coil I'm aware of has been replaced as mentioned in my original post.
#5??? Choke wide open implies not engaged at all...not fully engaged.
IME at best you will get inconsistent readings and risk damaging your arm/shoulder. When I tried this on a 214 rehab some years ago, I did the thumb over spark plug hole test instead and checked valves (ok) and head gasket integrity instead. Then decarboned the head and piston just in case. Quit stumbling after that, but mine wasn't bad enough to choke/kill the engine with PTO engaged...so may not be a valid comparison. If you do the comp test, rely on a set of young arms/shoulders!
Could you provide some explanation about this: "When I tried this on a 214 rehab some years ago, I did the thumb over spark plug hole test instead and checked valves (ok) and head gasket integrity instead. "
That is an interesting idea 'spinning the crank backwards to keep the ACR out of the picture'. In theory it matters not which way direction the crank is rotating as long as both valves are closed during the compression stroke, right?
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Could you provide some explanation about this: "When I tried this on a 214 rehab some years ago, I did the thumb over spark plug hole test instead and checked valves (ok) and head gasket integrity instead. "
I tried the compression check method posted earlier from the manual by TiredDeere210. Had a hard time getting any grip on the PTO sheave (manual PTO) with a rope and wore out my arm...only to get below-par compression values. So I reverted to my basic compression test...pull the plug, put your thumb/finger over the hole and spin the engine over. If you can't keep the hole covered...ie. compression pushes your thumb/finger off...it has decent compression. So I moved on to checking the valves, pulling the head and decarboning the engine. New head gasket, clean underneath and it ran much better. It never had a dying problem to begin with though. I was just being fussy I guess.
That is an interesting idea 'spinning the crank backwards to keep the ACR out of the picture'. In theory it matters not which way direction the crank is rotating as long as both valves are closed during the compression stroke, right?
I have no clue...just following the manual's advice. You can also disable the ACR, which isn't too hard to do. Learned this by watching an online video about a complete Kohler rebuild...don't have that link though. IIRC I found it by GoogleMachining "Kohler ACR Compression Test" or some similar search string. What I remember about that is you remove a cover on the block, look inside with a flashlight and you can see the spring that is part of the ACR...which you remove or unhook to disable the auto ACR. Of course I discovered that AFTER I decided the 214 was okay and didn't feel inclined to have another go at it. Someone with Kohler chops on the board can likely answer your question about crank rotation for compression checks.
Unless this is brain fart Monday, I believe I have always done compression tests on carbed engines with the throttle plate wide open...which is why I earlier questioned item #5 about closing the choke completely.
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Corkguy94, I don't want to lead you on a wild goose chase, so can you tell us for sure if you have an electric clutch or a manual type? The 200 series electric clutch is engaged by a toggle switch on the dash. The manual clutch is engaged by a lever on the dash. Post a picture of the right side of the engine with the engine cover removed, if you like.
We will be glad to go through the resistance and air gap routine, but it just doesn't apply to the manual type.

tommyhawk
I tried the compression check method posted earlier from the manual by TiredDeere210. Had a hard time getting any grip on the PTO sheave (manual PTO) with a rope and wore out my arm...only to get below-par compression values. So I reverted to my basic compression test...pull the plug, put your thumb/finger over the hole and spin the engine over. If you can't keep the hole covered...ie. compression pushes your thumb/finger off...it has decent compression. So I moved on to checking the valves, pulling the head and decarboning the engine. New head gasket, clean underneath and it ran much better. It never had a dying problem to begin with though. I was just being fussy I guess.

I have no clue...just following the manual's advice. You can also disable the ACR, which isn't too hard to do. Learned this by watching an online video about a complete Kohler rebuild...don't have that link though. IIRC I found it by GoogleMachining "Kohler ACR Compression Test" or some similar search string. What I remember about that is you remove a cover on the block, look inside with a flashlight and you can see the spring that is part of the ACR...which you remove or unhook to disable the auto ACR. Of course I discovered that AFTER I decided the 214 was okay and didn't feel inclined to have another go at it. Someone with Kohler chops on the board can likely answer your question about crank rotation for compression checks.
Unless this is brain fart Monday, I believe I have always done compression tests on carbed engines with the throttle plate wide open...which is why I earlier questioned item #5 about closing the choke completely.
What do you mean by 'decarboning the engine'?
Corkguy94, I don't want to lead you on a wild goose chase, so can you tell us for sure if you have an electric clutch or a manual type? The 200 series electric clutch is engaged by a toggle switch on the dash. The manual clutch is engaged by a lever on the dash. Post a picture of the right side of the engine with the engine cover removed, if you like.
We will be glad to go through the resistance and air gap routine, but it just doesn't apply to the manual type.

tommyhawk
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Corkguy94, I don't want to lead you on a wild goose chase, so can you tell us for sure if you have an electric clutch or a manual type? The 200 series electric clutch is engaged by a toggle switch on the dash. The manual clutch is engaged by a lever on the dash. Post a picture of the right side of the engine with the engine cover removed, if you like.
We will be glad to go through the resistance and air gap routine, but it just doesn't apply to the manual type.

tommyhawk
I would just unplug the pto when this happens and see if it clears up.
Quite a few of the 112 and the 212 that I have had a part of the 5 prong plug on the back of the ignition switch melted where the power comes from the solenoid. Loose/corroded connection caused problems when under load
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Thread Starter here: FWIW, I just ran a compression check, with a compression check tool. 120 PSI, 5 times. I don't have a compression problem. Might this be a fuel pump issue, since I have gone from 10 minute run time to 40+ minute run time after installing a new carb?
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