JD 425 AWS one cylinder dropping out so only half power...

   / JD 425 AWS one cylinder dropping out so only half power... #1  

sawmillbay

New member
Joined
Jan 4, 2011
Messages
7
Tractor
John Deere 425 AWS
Hello - I have a JD 425 AWS. I bought it new back in 1997, I think. For the past few months it drops to one cylinder resulting in only half power. When it does that I smell fuel. The coil/ignition module and plugs where just changed and that did not solve the problem.
The tractor runs like a top - no spitting or sputtering, doesn't smoke, even when the cylinder drops out. It will sometimes run on both for an hour and then lose the cylinder only to have it kick back in and out after that.
One mechanic says the whole engine needs to be torn down, another thinks that it may be electrical, ie: a loose or rubbing wire. I can live without a manicured lawn but I need to clear the snow in order to keep my business open.
Any help would be appreciated! Thank you.
 
   / JD 425 AWS one cylinder dropping out so only half power... #2  
When it cuts out pull the plug wires and check for spark. If losing spark on one side you at least have a starting point.
 
   / JD 425 AWS one cylinder dropping out so only half power... #3  
Sawmill - Next time the engine acts up, shut it off and do a compression test.

Also check the cylinder heads by hand to see how hot they are. Maybe poor coolant circulation causing the head to get too hot and cause the valves to stick open.

Have you been able to determine which cylinder is acting up?

Richard
 
   / JD 425 AWS one cylinder dropping out so only half power...
  • Thread Starter
#4  
No spark when it is acting up on the left side.
 
   / JD 425 AWS one cylinder dropping out so only half power...
  • Thread Starter
#5  
It is the left side. Single gal here, not sure how to do a compression test...
I have had it to the shop several times and they can't seem to get it to act up.
 
   / JD 425 AWS one cylinder dropping out so only half power... #6  
Sounds to me like it's an intermittent electrical problem in the ignition system that develops after the engine heats up.

You say that the ignition coils are new?? There are two --- hopefully, both are new. Next time you lose a cylinder, you might want to try switching the ignition coils to see if the problem moves to the other side or remains on the left side. If the problem remains on the left side after you switch the ignition coils, then you have an indication that the ignition coils are not the source of the problem.

In addition to the ignition coils you have a "pulser" coil for each side. The pulser coils generate the charging signal for the ignition coils. (Best way I know to explain it) Sounds like the problem might be in the left pulser coil. So, if you have someone working on it, ask them to check that out.
 
   / JD 425 AWS one cylinder dropping out so only half power... #7  
I agree with what Bruce said.

Richard
 
   / JD 425 AWS one cylinder dropping out so only half power...
  • Thread Starter
#8  
Ok - thank you so much! I will have them check that out and let you know!
 
   / JD 425 AWS one cylinder dropping out so only half power... #9  
I also was going to suggest swapping the external ignition coils and see if the problem swaps too. If it does, replace that coil. If not you have to dig deeper. As in the coils that trigger the external coils bruceatlam refered to.
 
   / JD 425 AWS one cylinder dropping out so only half power... #10  
Any update??
 
 
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