Won't start when hot

[sequences]

Hello, We have a 1979 JD 2040. Starts fine when cold. We do plug it in when temp is below 30f, to make things easier. The starter does have some bad spots, but if you get past them (hear the click) it will go. Problem is once the engine gets hot, and you have to turn it off for something, it will not restart. No clicks, nothing. Give it some time to cool down, and it will start again. It has new batteries, new positive and neg wires. Suspecting the starter or solenoid, but not sure what to look for. Where to start? This happens more in hot weather.

 

[oldnslo]

Have you checked to see if you are getting voltage to the starter? That is first place I would start is where do I have voltage and where do I not have voltage. Typically click indicates starter solenoid is working.

 

[sequences]

Have you checked to see if you are getting voltage to the starter? That is first place I would start is where do I have voltage and where do I not have voltage. Typically click indicates starter solenoid is working.

Gathering ideas to try for a game plan. Tractor has a loader, with a heavy frame that blocks access to starter. Also distracted with many chores that all have to get done now. Anyway, once we have a plan we'll get going on it. Raining today, and no cover. We plan on cleaning contacts at starter/solenoid; think we can do that without taking loader off. Have replaced starter in the past without removing loader, but it is a real pain-literal and figuratively. Had to adapt tools, and my hands were the only ones that could get in there. Not doing that one again!

 

[Tx Jim]

If your 2040 has 3 cylinder engine is serial # below or above 266750? Above serial # 266750 2040 has closed-center hyd's. Hyd pump isn't remaining in de-stroked mode then when attempting to start hyd is attempting to buiild pressure which increases load on starter while attempting to start engine. Either rapidly turn steering wheel from side to side while attempting to start engine or install/use hyd pump de-stroking screw

 

[Doughknob]

Some electrical component is heating up and not making proper contact when so. Could be wire splice, switch, relay…..

Those cans of computer keyboard cleaner work to cool things. Cheap way to diagnose, spray on hot starter relay for a while and see. Or spray on switch. Etc…..

 

[Harry in Ky]

Many possibilities, some already mentioned. It starts when it's cold, but not when it's hot? No click or any starter related action?

If I were faced with that situation, what would I do? Wait until it does it again, then go fishing with a volt meter? With a hot starter on a hot engine, and behind a loader frame. By myself. Trying to reach the key with one hand and probe with the other. Probably not my plan. I would take a piece of 12 or 14 gauge wire, long enough to reach from the start terminal on the solenoid, up to the positive battery post. Put a ring terminal on one end, and attach it to the starter while the engine is still cold. Maybe test it by flashing the other end of it to the battery post just to make sure it works. Place the bare end somewhere safe but where I can reach it from the seat. Now start the tractor with the key and run it up to temperature. Whatever that takes until it won't start with the key. Now try the jumper wire and see what happens. If it starts, the starter and solenoid are not the problem. Start looking at neutral switch, start relay, related wiring and connections, etc. If it still won't start, then wait for it to cool down again and plan on pulling the starter.

 

[Tx Jim]

I reread OP's statement & decided 2040's non-starting problem is electrical not hydraulic related as I previously implied. I think starter solenoid plunger is binding from heat. Another thing that might help warm engine start better is relocating factory ground cable from RUSTY battery box to engine block or starter mounting bolt if not presently relocated. JD also offered a starter relay kit to supply more amperage to solenoid engagement wire(see photo below)

 

[glcaines]

Your problem is almost definitely a failed thermister. I've had three John Deere tractors with exactly the same symptoms caused by a failed thermister. The standard symptoms are that the engine will start immediately when cold and will continue to run without problems, even when hot. If you shut the engine down, it won't re-start until the engine cools down even with the starter spinning fast. Actually, it is the thermister cooling down, not the engine. Once the thermister cools down, usually 30 minutes or so in my cases, the engine fires right back up. The thermister on my JD tractors was buried in the middle of the wiring harness directly below the steering wheel, and somewhat difficult to access. It takes me about an hour to replace the thermister. The same thermister is used on all JD tractors as far as I know, and the part number is: LVU10323. I believe I paid ~$5.00 for my first one and around ~$12.00 for the last one I bought. A lot of people have gotten ripped off with expensive repairs that were not needed due to the thermister failing. I was initially told by a JD dealer that I needed a new injection pump for a very large price, when this happened to me the first time. Fortunately, someone else familiar with JD tractors gave me the real story and I took my tractor back from the dealer and replaced the thermister myself.

 

[Harry in Ky]

He said the starting problem involves the starter not working. Doesn't sound like "spinning fast but not starting".

I'm no Deere expert, but I wasn't aware that any 40 series tractors used a thermister. Always good to learn something new.

 

[Tx Jim]

He said the starting problem involves the starter not working. Doesn't sound like "spinning fast but not starting".

I'm no Deere expert, but I wasn't aware that any 40 series tractors used a thermister. Always good to learn something new.

Harry you're correct JD 40 series tractors such as a 2040 had no thermistor(LVU10323)