JD 1640: No start when warm

[cray54]

I'm working on a John Deere 1640 that will not start if it has reached operating temperature and is then shut off.

I assume this is related: when it is summertime, it still needs glow plugs to get it to fire when it is at ambient temperature and cranks quite slowly. I have tested voltage at the starter while cranking and it is not significantly lower than the voltage at the battery when cranking.

I understand there is some sort of de-stroke valve on the hydraulic pump that can cause this problem, but I cannot find further information. Is the de-stroke problem a result of a failed part? How do you properly adjust a de-stroke valve and do you need to do it every time?

Thanks,
Chris

 

[Tx Jim]

De-stroking screw part # AR33249. De-stroking screw can aid starting by keeping frt hyd pump from loading starter trying to pump oil while cranking. Screw must be turned down before cranking and then turned back up to allow hyd pump to pump oil. De-stroking was an added option just to aid hard starting tractors. JD 1640 has no glow plugs.

 

[cray54]

Why would a manual de-stroking screw be necessary now when the tractor used to start more easily without it (I would assume some sort of failure occurred in the past)?

I am new to tractors / diesels (but not to engines / machines), so I apologize if I mix up the terminology. The manual indicates the 1640 has a "thermostart aid" which I seem to have incorrectly referred to as "glow plugs". What is the difference between those two terms / functions?

Thanks,
Chris

 

[Tx Jim]

Thermostart is a heating element in the intake manifold. Whereas glow plugs are screwed into the cyl head. Normally if battery,starter and batt cables are good then hard starting on closed-center hyd tractors can be attributed to high pressure internal hyd leaks causing hyd pump to put excessive strain on the starter.

 

[cray54]

I tried some of the methods to reduce hydraulic load (lower 3-point, unload loader, unload accessory lines) and moved the steering wheel during cranking to see if cranking speed changed. It did not, so my current assumption is that de-stroking the pump would not help.

The starter on our skidder is supposed to fit the 1640, so I will swap that to see if maybe the starter is the problem.

Thanks,
Chris

 

[Tx Jim]

I tried some of the methods to reduce hydraulic load (lower 3-point, unload loader, unload accessory lines) and moved the steering wheel during cranking to see if cranking speed changed. It did not, so my current assumption is that de-stroking the pump would not help.

The only method mentioned above that will noticeably aid starting is rapidly moving steering wheel back & forth while attempting to crank.

First thing to do if battery ground cable is still attached to battery box is relocate the grd cable to engine block preferably to one of the starter mounting bolts.

 

[cray54]

Battery cables are still attached to the sheet metal, but that part of the system is well connected (I have checked and tested it). I used spare cables to test connecting directly to the block and found the system cranking at the same speed. I'm going to pull the starter and check that before going too much further.

 

[Tx Jim]

Battery cables are still attached to the sheet metal, but that part of the system is well connected (I have checked and tested it).

Battery boxes have been known to rust and get bad connection where box attaches to clutch housing. More amp's of current will get to starter if ground cable is attached directly to starter mounting bolt.

 

[cray54]

Battery boxes have been known to rust and get bad connection where box attaches to clutch housing. More amp's of current will get to starter if ground cable is attached directly to starter mounting bolt.

This battery box has not rusted, nor has it developed a bad connection. I tested this by temporarily connecting the negative terminal to the starter bolt as others have also suggested. It resulted in no measurable current or voltage changes at the starter. Also, it made no noticeable difference in starter behavior.

The money to be spent on repairs is not my own, but that of my grandmother. I believe I am being frugal on her behalf by only repairing systems that have failed or are failing. In this case, I do not believe a new ground cable and configuration will be a good use of her money.

Thanks again for the help and suggestions. I'll post once I have the starter tested and possibly rebuilt.

-Chris

 

[Tx Jim]

This battery box has not rusted, nor has it developed a bad connection. The money to be spent on repairs is not my own, but that of my grandmother. I believe I am being frugal on her behalf -Chris

Chris
I'm glad your being "frugal" with your Grandmothers money. But there has been a many starter repaired/replaced in the past because the ground cable had a significant lose of amperage between where it attaches and the starter and I felt I should point that fact out to you.

 

[Farmer Frank]

I used to have this problem on my 4020. I was told to turn the steering wheel back and forth rapidly when starting to take the load off the starter or whatever. This little trick solved the problem. I have learned with the 4020 and the 4630, all connections have to be clean and tight and the battry(s) have to be FULLY charged. I installed a cut-off swith on the battery box on the Cat backhoe so it would not discharge, seemed to have worked. Again, all connection have to be clean and tight....:thumbsup:

 

[cray54]

New starter fixed everything. I will continue to lower 3-point, unload loader and unload accessory lines as the manual states this should be done prior to starting (even if it does not reduce hydraulic load "noticeably").

Next I will re-test my connections, clean them and apply dielectric grease to contact points.