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When I engage the mower deck on my 425 it kills the engine. Once everything is warmed up it works OK. The blades seem to turn freely and the gear box oil has been checked.
 

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Jackson, you really don't habe a problem, other than a "cold" engine.

When an engine first starts, the aluminum pistons expand, a lot & quickly, your oil hasn't enough time to fully circulate through your engine, and the oil doesn't "splash" onto the cylinder walls. As your engine warms up, the cylinders expand, you now have oil to all of your bearings, and the oil is "splashing" onto your cylinder walls. A "cold" engine is struggling to run on its own, never mind trying to also run a deck!

Start your engine, run at 1/3 to 1/2 throttle for 2 or 3 minutes, THEN turn pto on. My 322 is the same and will die every time if it's not warmed up a little. Bob
 

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When I engage the mower deck on my 425 it kills the engine. Once everything is warmed up it works OK. The blades seem to turn freely and the gear box oil has been checked.
I had a similar issue my 425. I had read many posts that it wasn't unusual just let it warm up. Turned out I was down a cylinder. Fixed that issue and it runs strong. Could be nothing or you could be down power. How is it when you have the deck engaged and are mowing?

Jim
 

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Back close to 20 yrs ago I had a 425 and it did the same thing . Wasn't the engine, I'm thinking it was the solenoid that engages the mower deck.
 

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The ignition coils are a known issue with that engine, which is likely the reason it was down one cylinder. Coils behave strangely when they get hot or aren't hot, like when first starting the engine. Bottom line, the load being put on the engine is causing the engine to quit.

It's not a matter of the engine needing to be warmed up which causes the engine to stall. It's an issue with the ignition system not providing enough of a spark that when the engine is placed under a load, the engine stalls. The tractor uses a coil for each cylinder. Chances are the spark plug on the cylinder with the weak coil will not be clean and burning properly, which is an easy way to determine which ignition coil is bad.

There is also a diagnosis system for testing the coil which is outlined in the Technical Service Manual. Anyone who owns any model John Deere tractor, the Technical service manual is worth its weight in gold......OK, well maybe not Gold, but they are extremely handy and extremely valuable.They are also not cheap, but they are the source of solving any problem which can come up with the machine.

The PTO is the greatest load to place on the engine very quickly. If you were to hitch the tractor to a very heavy object and push the forward hydro pedal, the load would likely cause the engine to stall as well. Its the sudden load on the engine which causes the stall.

My money is on the ignition coil. Pull the spark plugs out one at a time and carefully check them and make sure you know which plug came from which cylinder. The plug which is covered with carbon or other signs of unburned / inefficient combustion chamber activity is generally the cylinder with the bad coil. A weak coil means the spark plug isn't firing as intensely as it should, so the plug builds up carbon and other "crud" which normally would be consumed in the combustion process.

If it has been a long time since the tractor was serviced and the fuel filter, air filter, spark plugs replaced, each of those items also can impact the engines operating efficiency. But an engine which stalls and then restarts and stalls is most often the victim of weak spark from a defective ignition coil.

The ignition module also impacts the coils efficiency. It's not uncommon for the ignition module to need to be replaced as well. With an Ohm meter, you can test the ignition coil for resistance. I will get the procedure and post if for your review. Please note, the machines serial number determines which testing procedure to use.....
 

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The following are the pages from the Technical Service Manual which deal with igntion system and component testing. As I mentioned before, the serial number of the machine determines the specific testing points for the procedures outlined.

The following pages start with item 1 and go through the various steps and symptoms for the portion of the system which should be tested to determine whether the component needs to be replaced. The pieces most typically involved are the igniton coils and the ignition module.

Ignition coils (2 are used, one per cylinder) for the 425 are John Deere part number AM120732 and retail at $54.28 each


Amazon.com: john deere am120732

The ignition module for the 425 is John Deere part num ber AM128906 and retails for $28.95, here they are on Amazon for your convenience.

Amazon.com: John Deere Original Equipment Module #AM128906: Gateway
 

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Here is a simple check. My friends 445 was running on one cylinder. The top of the spark plug unthreaded.:laugh:
 

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On a 425 we have we've always had to have the engine at full throttle and warm for the deck to engage without the engine cutting off. It's been like this for the last 25 years. 445's or 455's are a different story. Those tractors I could have at half throttle and they would engage the deck just fine.

Rick
 

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When I engage the mower deck on my 425 it kills the engine. Once everything is warmed up it works OK. The blades seem to turn freely and the gear box oil has been checked.
My 425 would always die if I engaged the mower deck too soon after start up. I always needed it to warm for a minute or two. I would say this is normal unless you have some other associated symptoms. As another power said, Kawasaki engines in that mower seem pretty cold natured for whatever reason. I am also thinking the deck has a high level of friction so trying to go from zero to running 2000 rpm's in an instant is sometimes too traumatic for the engine. This is a shaft driven deck so there isn't a lot of slippage in the system until the power hits pulleys and belt.
 

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This issue is not limited to Deere mowers; Our 18 year old Simplicity rider does the same thing. We have to warm it up in order to engage the PTO. It's been that way for years.

Brian

When I engage the mower deck on my 425 it kills the engine. Once everything is warmed up it works OK. The blades seem to turn freely and the gear box oil has been checked.
 

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I've had this happen to my x 584 (only 33 hrs). I'm assuming it doesn't matter on hours or year, if the engine has not warmed up some and you've got an air cooled gasser you could run into this? I had not noticed it in the spring or summer here in WI but the last two times I've gone to mow, it's been about 45F outside. I've started it up, and only about 30 seconds later I've turned on the PTO because I don't want to just sit there at 1/2 throttle burning fuel for nothing.
 
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