/ John Deere 4110 diagnosis #1  

SunnyValley

New member
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Feb 4, 2026
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9
Tractor
4110 JD
Hi all,

I just purchased a new to me 4110 with just over 300 hours. It clearly needed a bit of work, but it was the only useful tractor in the budget since we bought land 4 years ago.

I was able to drive it on the trailer with some low power issues and puffs of black smoke. It would idle fine, but wasn't happy in gear. Wiggling wires on the fuel solenoid would shut it down, so my hopes were that it would be an easy fix. I replaced the solenoid and the smoke cleared up. The tractor would idle perfectly now without any smoke. Loader worked great in neutral.

The new issue was that the solenoid would kick the engine off in gear or when the pto was engaged. "Click". I started checking the specs for all safety switches. The seat switch was reading 30ohms on a and b when seated. That is high, but it shouldn't tell the fuel solenoid to shut down when the rear pto is engaged, as you are able to run that while off seat, I think? (Haven't been able to try yet)

I decided to do some regular maintenance. The old tractor was filthy from the brine and slush soaked drive home. Oil was overfilled, trans oil was overflowing out of the dipstick tube, and there was likely a 1/4 cup of sand and dirt in the gas tank, along with a bit of water. I drained and cleaned the tank, replaced the fuel filter, cleaned the housing, and blew out return lines. Put a new air filter in while I was at at. Added a splash of seafoam to fresh diesel and let it idle for 20 minutes. No issues. It idles fantastic. I go to start it in the morning.... strong crank, no start. Black smoke when trying to crank. I decided to check the battery. Charged it up and ran two test cycles with my battery repair charger. Green light there. Im feeling like there are electrical gremlins at this point, so I pull the computer under the seat and inspect the board. No hot spots, no cracked solder. Looks fine. Next I check grounds. Sure enough, the battery negative to frame is hanging on by a thread.... literally. Gentle wiggle snaps it right off. I got it! No.... brand new cable. Cleaned connections. Still won't start. Now I'm circling back to the solenoid. It's new, but is it working? 32ohms on terminals that should be at 12.4. That isn't good, but would it cause no start condition?

I am about to bypass the seat switch just to rule it out. New JD fuel solenoid inbound. I will update when I make some progress.

Any advice would be appreciated.

Thanks for reading,
James
 
/ John Deere 4110 diagnosis #2  
It sounds like you are well versed in mechanical troubleshooting. I believe you are on the right track with the seat switch as an additional problem.
 
/ John Deere 4110 diagnosis #3  
That is high, but it shouldn't tell the fuel solenoid to shut down when the rear pto is engaged, as you are able to run that while off seat, I think? (Haven't been able to try yet)
seat switch should be tied to pto switch.
Sounds like a lot of poor maintenance for a low hour unit
 
/ John Deere 4110 diagnosis #4  
Any thoughts on how the engine oil and hydraulic oil become over filled? Was there any water in there? I'd keep a close eye on both to see if they continue to rise, which they will unless everything was the result of vandalism.
 
/ John Deere 4110 diagnosis #5  
When I checked ohms on an OE 4110 fuel solenoid awhile back I got similar readings as you did. Solenoid functioned fine and is still installed.

Here's that discussion.


Issue I was having back was an intermediate start condition; would always crank, sometime would start, sometime not. Turned out to be a burnt board which integrates the safety switches to the start circuit. There's a discussion of that on a previous TBN thread; search my posts.
Good luck
 
/ John Deere 4110 diagnosis
  • Thread Starter
#6  
It sounds like you are well versed in mechanical troubleshooting. I believe you are on the right track with the seat switch as an additional problem.
I have definitely spent some time wrenching on vehicles, but this is my first Diesel machine.
seat switch should be tied to pto switch.
Sounds like a lot of poor maintenance for a low hour unit
I believe it is... I ended up just unplugging it and capping the open terminals. It completely solved the stalling in gear/pto.
Any thoughts on how the engine oil and hydraulic oil become over filled? Was there any water in there? I'd keep a close eye on both to see if they continue to rise, which they will unless everything was the result of vandalism.
I am guessing that the previous owner had someone do a drain and fill. They might have not drained everything and filled to the service manual ammounts. I haven't noticed any high levels since.
When I checked ohms on an OE 4110 fuel solenoid awhile back I got similar readings as you did. Solenoid functioned fine and is still installed.

Here's that discussion.


Issue I was having back was an intermediate start condition; would always crank, sometime would start, sometime not. Turned out to be a burnt board which integrates the safety switches to the start circuit. There's a discussion of that on a previous TBN thread; search my posts.
Good luck
That is what I have discovered as well. Seems the specs in the service manual are out or not critical. The brand new JD solenoid was closer to spec, but still high. It works though.
 
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/ John Deere 4110 diagnosis
  • Thread Starter
#7  
After going through the rest of the fuel system and unplugging the seat switch, I managed to get the tractor starting and running. There was clearly an air lock somewhere. Possibly some contamination in the fuel near the end of the line as well. I had to crack all 3 injector lines at once and crank for 10 second intervals for a few rounds to get the bubbles out. There was a loose fuel line connection on top of the injection pump as well. My Dad told me to crack the injectors on day one. I told him this was a self bleeding machine. He replied "It's a diesel tractor". Eventually I listened. Now I know.

Overall the tractor is running and working decent. I am smoking from the exhaust and hearing a distinct "popping" at cold start. Once it warms up, the smoke and "popping" settles down and I can run the machine for a few minutes as if it were in perfect health. Once I get it working and hot, the breather tube starts smoking and dripping oil pretty good. Otherwise, there is plenty of power.

I am now looking in the direction of stuck rings, as this was a neglected machine that did a lot of sitting. I am really hoping someone didn't do damage with ether or something. I am told this "popping" could also be injector related, if not a stuck valve or something similar?

Next steps are adding some Marvel Mystery Oil to the engine oil/fuel and working it hard (once I rebuild this severely neglected mower deck). If things don't clear up after a couple tanks of deisel, I will move on to replacing injectors and fuel lines. Some of the lines are quite stiff and will eventually be an issue anyways. If there are still issues, I guess the top comes off for a look. At least the Marvel Mystery will have cleaned everything up for me.

Cheers,
James
 
/ John Deere 4110 diagnosis #8  
Overall the tractor is running and working decent. I am smoking from the exhaust and hearing a distinct "popping" at cold start. Once it warms up, the smoke and "popping" settles down and I can run the machine for a few minutes as if it were in perfect health. Once I get it working and hot, the breather tube starts smoking and dripping oil pretty good. Otherwise, there is plenty of power.

I am now looking in the direction of stuck rings, as this was a neglected machine that did a lot of sitting. I am really hoping someone didn't do damage with ether or something. I am told this "popping" could also be injector related, if not a stuck valve or something similar?

Next steps are adding some Marvel Mystery Oil to the engine oil/fuel and working it hard (once I rebuild this severely neglected mower deck). If things don't clear up after a couple tanks of deisel, I will move on to replacing injectors and fuel lines. Some of the lines are quite stiff and will eventually be an issue anyways. If there are still issues, I guess the top comes off for a look. At least the Marvel Mystery will have cleaned everything up for me.

Cheers,
James
Why not do a compression test first? Didn’t this series use a pcv valve? Is it any good?
Normally, I would send the injectors out for testing but looks like these may be inexpensive enough to just replace
@thepumpguysc may have a different opinion
 
/ John Deere 4110 diagnosis
  • Thread Starter
#9  
Why not do a compression test first? Didn’t this series use a pcv valve? Is it any good?
Normally, I would send the injectors out for testing but looks like these may be inexpensive enough to just replace
@thepumpguysc may have a different opinion
If I had a compression tester, I absolutely would! I plan on running the marvel mystery for a deep clean anyways. If issues clear up, then I am in luck. Would you suggest a compression test before running the oil or do you mean before pulling the valve cover?

My search came up with just a breather tube on these. I just see a tube going into the cover, but there could be something on the inside?

I noticed the injectors were quite affordable as well. I am going to get a new set on there with some fresh fuel line when I can get to the JD dealer next.
 
/ John Deere 4110 diagnosis #10  
If I had a compression tester, I absolutely would! I plan on running the marvel mystery for a deep clean anyways. If issues clear up, then I am in luck. Would you suggest a compression test before running the oil or do you mean before pulling the valve cover?

My search came up with just a breather tube on these. I just see a tube going into the cover, but there could be something on the inside?

I noticed the injectors were quite affordable as well. I am going to get a new set on there with some fresh fuel line when I can get to the JD dealer next.
Yes, I would do a compression test before adding anything else to the equation. You can get a tester pretty cheap these days. Doesn’t have to be super duper top shelf to see if things are in the same ballpark. Any chance you could find a loaner or rental?
 
/ John Deere 4110 diagnosis
  • Thread Starter
#11  
Yes, I would do a compression test before adding anything else to the equation. You can get a tester pretty cheap these days. Doesn’t have to be super duper top shelf to see if things are in the same ballpark. Any chance you could find a loaner or rental?
Good to know. Thanks! We live in a community of farmers with diesel tractors, so I'm sure I could borrow one if I ask around. I was thinking a cleaning would be a good first step, but I guess I could be doing damage if there is something more serious than stuck/dirty valves/rings?
 
/ John Deere 4110 diagnosis #12  
Good to know. Thanks! We live in a community of farmers with diesel tractors, so I'm sure I could borrow one if I ask around. I was thinking a cleaning would be a good first step, but I guess I could be doing damage if there is something more serious than stuck/dirty valves/rings?
Yes, quickest and easiest way I know of to “see” root causes. Not really a more damage thing as it is applying “kiss (keep it simple stupid) principles to your troubleshooting steps. Sometimes we tend to let emotion (gotta have tractor running) override our brain looking for a quick fix.

If you find some loaner tools, ask for a leak down tester too (just in case)
 
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