Has anyone else had trouble with the starter on a JD 4120 series? I understand this same unit is also used on skidsteers, etc that use this 4 cylinder JD Powertech engine. Mine starting acting up about (4) years ago, but I was always able to get the tractor to fire by holding the key in the start position for a while. It wasn't too bad and I kind of looked at it as an anti-theft device. (2) weeks ago it wouldn go at all however and I pulled the starter and tested it with jumper cables and a battery. It seemed ok, so I put it back on and the tractor fired again. The next time I went to use it however, no go. I pulled the starter again and this time it would not work at all with the jumper cables. The local JD dealer wanted almost $300 for a new starter but I was reluctant to buy that, not only because of the steep price, but also because the original only lasted a couple years before it started acting up. I think it is a corrosion issue because, when it was intermittant, as I held the key over, I would hear a faint "crackling" noise from the starter area as the solenoid heated up and the juice began to flow. Overal, the tractor has been great and this is the only issue over (6) years. Thankfully, I was able to find a new starter on the internet for just over $100 and it is working fine now. If I get bored this winter, I will dig into the old starter and try and figure out why it failed. I will post back when an if I find out anything.
JD 4120-4720 starter issues?
- Thread starter wolc123
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AKfish
Super Member
- Joined
- Oct 1, 2004
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- 5,419
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- Tractor
- JD 5115M; JD 110 TLB; JD 4720; Ford 9N; JD X300R
Haven't heard about this problem before. 'Course I've never searched through the old posts, either....
Have noted starter problems with the JD lawn tractors, though. JD just issued a recall/retro for replacement starters on the X300R tractors.
Be curious to know if the current 4x20 series tractors have a different model/part number for the starter motor versus the model/part number for say; your 4120.
Might be an easy check on JD Parts.
Keep us in the loop. Thanks.
AKfish
Have noted starter problems with the JD lawn tractors, though. JD just issued a recall/retro for replacement starters on the X300R tractors.
Be curious to know if the current 4x20 series tractors have a different model/part number for the starter motor versus the model/part number for say; your 4120.
Might be an easy check on JD Parts.
Keep us in the loop. Thanks.
AKfish
9973720wb19
Platinum Member
this is not going to help your problem, but i'd like to mention that i had a JD with a Yenmar engine and it fired up quick. now i have a 2011 jd 4720 and even with pre-heating, it needs to crank a few times before it fires up. just conserned it seems like a problem waiting to happen
My 4120 always starts right away after it cranks, the problem was that it would not begin cranking. JD has gone to a different P/N on the new 4120 series. The bad starter on my tractor was a BOSCH, JD P/N RE508922. That part is no longer available from JD. As far as I know, I may be the only one who had trouble with the old part. At least no one else has posted about similar issues yet (I did an extensive search of old posts before starting the new thread). The fact that an aftermarket replacement is available for around $100 tells me that there must be some pretty good demand for this part. Again, this aint a real big deal and I am generally quite happy with the tractor. At this point I am only out about $120, including shipping costs, and about an hour of my time. That is less money and time than any other tractor I have owned has cost me in unscheduled maintenance over a 5 year period.
May not apply in your case but a couple of years ago my 4720 had a problem that I was convinced was the starter. Your description sounds almost exactly like what I was having. I contacted my service manager and he had his mx tech stop by. They had trouble believing me that the starter was the problem but after 30 minutes the tech said that it was most likely the starter and he would order a new one. As he was finishing up however he got an accidental starter activation as he was moving one of the cables. The battery and the terminals had been ruled out previously by both me and the tech. What it was was some defect in the cable swage crimp that was detected only by twisting/moving the cable moderately aggressively. New warranty cable and no more problem. Even their tech said he had never seen that problem from a cable before.
Similar problem but mine is confined to the starter/solenoid assembly for sure as it wont even spin when directly connected to a battery. I am thinking it is caused by corrosion on the internal connection between the solenoid and starter motor. I will post back this winter if that turns out to be the case.
