755 gremlins

[kmmn]

My 755 seems to be possessed by gremlins (not the AMC variety).

Problem #1 - The Temp Warning light comes on after running the tractor. I don't think it's electrical, because it does seem really hot. So far I've checked the screen, which was clean, but the sky erupted, so I'll need to pick up later. I'm thinking coolant level, belt, radiator cap, thermostat, water pump.

Problem #2 - After shutting down the tractor while mowing, the PTO (rear) won't readily engage. (It does after a few tries and turning the tractor on/off (see problem #3). The seat switch had been sticking, but I sprayed some PB Blaster on it a couple of cuts ago, and that's been working pretty well. Since it eventually works, I'm skeptical of it being the magnet and I have had other electrical problems lately, all tracking back to worn wiring.

Problem #3 - The tractor keeps running after turning the key to Off... it's never done that in 23 years.

I don't believe in coincidences (although the tractor is 23 years old), so I wonder if #2 & #3 are related. (As far as I know, the only electrical component of the cooling system is the warning light, so I'm leaning toward that being mechanical).

I appreciate any suggestions.

Thanks!

 

[Spanner]

Sounds like the whole tractor is overdue for a re-furb - especially the wiring.

#2. Fit a new Seat Switch assembly. You have an unreliable switch so troubleshooting the PTO is hit-&-miss.

You need to work with 'known good' components, not "PB Blast-&-hope-it-works".

Pull all the fuses (One at a time) and replace with brand new shiny fuses. Apply di-electric grease to the blades also.

#1. While waiting for you to fit that switch, tell us what colour is your coolant? Lime green(?) or rusty orange(?)

#3. Ignition switch may be worn and not 'disconnecting' the stop solenoid on the Injection Pump. Mechanical linkage from the Solenoid to the Pump may be worn and binding. Physically eye-ball this mechanism when you switch the key to 'Off' and report whether the solenoid de-activates the fuel supply lever. Solenoid may be 'sticking' ?

 

[kmmn]

I only applied the PB Blaster because the plunger was sticking... I wasn't having any PTO issues at that point, but I agree that there are too many variables.

The coolant is full and lime green


Thanks!

 

[Spanner]

The Plunger was sticking because it was 'dirty' with dust or rust. PBB moves the contamination into a puddle inside. You may have caused your own fault. Replace the switch assembly.

Green coolant is good.

Observe and report Item #3.

 

[kmmn]

It was not the switch (I bypassed it as a test). According to the wiring diagram, the PTO circuit is connected to the temp warning light circuit (JD's idea to prevent really overheating it, I guess), so that explains the problems occurring at the same time. Last night, the light came on during a restart, after running for a couple of minutes, so there's no way it was that hot, yet). I ran through the wiring loom and found a fray making contact with the body of the starter... when I opened the loom, the frayed wire was orange w/yellow (the temp sensor wire). There are enough repairs to the harness that I'm going to see if JD still offers a wiring harness, but it looks serviceable, for now. Thanks!

 

[Spanner]

Hey thanks for the follow-up.
Great that you have it figured out. Sorry I may have mis-read and took Probs #1 &#2 separately thinking #2 was seat sw. & PTO operation alone.

You can split the loom and make your own replacement, one wire at a time if necessary.

Did you make any sense of Prob #3 ?