Help with 646 LBH Hydraulic system

Apparently, this has been your tractor for some time and it performed well up to just recently. I highly doubt that your real problem stems from the wrong oil but......a thorough oil change certainly won't hurt and it will eliminate that issue.

I would be more inclined to suspect the banana plate and other linkage under the tractor. That's where I would look first. You need a helper. Get them to sit on the tractor (no keys in the ignition) while you crawl underneath with a trouble-light. Locate the travel/lift valve. What you are trying to determine is this. When your helper puts the travel lever in full forward and then steps on the pedal on the right side, does the spool in the travel valve move all the way out or in? And if they move the travel lever to full reverse, does the spool move all the way out or in? If the banana plate and associated parts are badly worn or if something has been broken or bent or come undone, then you are not getting full movement of the spool in the travel/lift valve and that's what is impeding your movement.

Before changing out the oil, that's where you need to focus. Locate your parts manual in the Library here and study that linkage. Print out the pages so you can refer to them while you are under the tractor.

Hydriv said:

Apparently, this has been your tractor for some time and it performed well up to just recently. I highly doubt that your real problem stems from the wrong oil but......a thorough oil change certainly won't hurt and it will eliminate that issue.

I would be more inclined to suspect the banana plate and other linkage under the tractor. That's where I would look first. You need a helper. Get them to sit on the tractor (no keys in the ignition) while you crawl underneath with a trouble-light. Locate the travel/lift valve. What you are trying to determine is this. When your helper puts the travel lever in full forward and then steps on the pedal on the right side, does the spool in the travel valve move all the way out or in? And if they move the travel lever to full reverse, does the spool move all the way out or in? If the banana plate and associated parts are badly worn or if something has been broken or bent or come undone, then you are not getting full movement of the spool in the travel/lift valve and that's what is impeding your movement.

Before changing out the oil, that's where you need to focus. Locate your parts manual in the Library here and study that linkage. Print out the pages so you can refer to them while you are under the tractor.

Click to expand...

Thanks fellas for all the response.
Tom
Yes I have had this tractor for some time now. I did not really get to use it like I did the other day. Most of the time it was to pull it out of the garage and out of the way. The other problem for me is finding the helper to sit on the seat while I am underneath poking around. Help is hard to find these days. lol
I will check out the movement of things and poke around further before I change out the oil.

Bart
The problem seems to be only after the tractor gets hot. Yesterday I removed the front grille assembly. The oil cooler was complely blocked with a blanket of thick tar like gunk. I cleaned that off and put it back together. I did not have anymore time to test her out afterwards. My time was up

Nutcase446
I do not believe there is a dealer anywhere close to me. I would have to investigate that further. I am quite confident in the knowledge on this forum and also appreciate the help that everyone here has to offer. My problem is not so much taking things apart but getting them back together with no spare parts.

I will report back as soon as I get back up there to tinker.

Hey guys, sorry for the snails pace.. I went to do some checking on the 646 and now I can't get her to start. I am not sure but it seems like a neutral switch problem (just guessing). When I turn the key, I get just the red light on the dash and nothing else.. no clicks noise or anything else. Battery seems ok and I even tried to give her a jump with a battery charger.. no change.

I took a few photos of underneath what looks like at least one safety switch. Is there a way to bypass that switch?? Also, I took the liberty of snapping some shots of the bannana plate and whatever else is under there. Anything obvious?? I did not have any help with me so I could not have anyone move the travel lever back and forth, but there seemed to be way too much slop and free movement with that plate and linkage.

Not sure what you guys can tell from the photos but please fire away. I need to get this thing started it is blocking the whole fleet behind it.

Thanks















sorry guys if the photos are a bit much. I wanted to include as many as possible.

The Parts Manual indicates that there are TWO neutral safety switches on your tractor that are wired in series with each other and are wired in series with the ignition switch and the starter solenoid.

Either one of the switches has failed or it is not being actuated to complete the start circuit or a wire is off or a wire is broken or a wire is corroded.

Here's the simple test.

Locate the starter motor. Hopefully, you have a clear view of the rear of the starter solenoid that is piggybacked onto the actual starter. You will see the heavy wire coming from the battery to the large lug on the solenoid. There will be a small lug next to it that receives the power from the keyswitch via the two safety switches. Use something metal (old screwdriver) to create a short circuit between the big lug and the small lug. Just make sure the trans-axle is in neutral when you do this. If the ignition key is turned to ON, the engine will start if you short those two terminals together. The instant the engine starts, remove the short.

Now you know that power is not getting to the starter solenoid..

- use a test light to see if power is leaving the keyswitch S terminal when the key is turned to START. If you have power at the keyswitch, then it's OK.

- follow the wire that leaves the keyswitch to the first safety switch and look for power on both sides of that switch when the key is twisted to START.

- if you get power on one side but not the other, then either the plunger of the switch is not being depressed far enough or the switch is defective.

- if you do get power on both sides with the keyswitch turned to START, then follow the wire to the next safety switch and repeat the test.

If you have a Multi-Meter, then it will have various scales on it that will measure AC volts, DC volts, Amps and a thing called OHMS, which is resistance to the flow of current.

Begin by locating the DC VOLTS range on the meter. You should have a red probe and a black one. Put the red one on the battery + terminal and the black one on the battery - terminal. The meter should read 12 volts. If so, then you now know how to measure DC volts.

With black probe touching clean metal (good ground), you can use the red probe to determine if the key switch is delivering 12 volts to the START circuit when the key is turned to START. The meter needle or LCD scale should flip back and forth every time you twist the key and release it from the START position. Once you have that figured out, it's a simple matter to repeat this process as you follow that wire to each safety switch. Obviously, you should see 12 volts on at least one side of each switch unless the wire going to that switch is broken internally or corroded internally.

I spoke about the OHMS scale. Reset your meter to OHMS. DIsconnect the positive wire that goes to the tractor's battery to protect your meter while using the OHM's scale.

With the meter set to OHMS, touch the red and black probes together while watching the meter. You should see a change in the LCD readout or the meter needle should move to the left side of the scale. That indicates "continuity", meaning that there is NO resistance to current flow. If the meter's internal batteries are OK, that's what should happen. IF it does not happen, then a new set of batteries will likely fix the problem.


Assuming that you have a properly working meter, remove the two wires going to the safety switch. While watching the meter. put the probes across the switch. It does not matter which probe you put on which terminal on the switch. Just make sure that the probes are not touching one another but are touching the switch terminals. DID the meter move like it did when you touched the probes together earlier? If so, then the switch is allowing current to flow through it. If the meter did not move, then you need to depress the switch actuator to see if you get current flow. IF you do, then the problem is evident. The switch needs to be adjusted so that it gets fully depressed when everything is in neutral.

Test the second switch the same way.

You can also put the probes on each end of a wire to make sure that wire will flow current. If you get a partial reading on the meter, then you are seeing a high resistance to current flow and that wire should likely be replaced.

If you get the tractor started using the method I described in my other post, you can perform whatever work you need to do as long as you don't stall the engine or shut it off. These switches are just there to make sure that the tractor isn't in gear when it is being started.

Forgive any typos or spelling this is from my phone.
When shorting the starter it did not get me started. With key in off position I get a spark. when shorting the starter. When the key switch is in the start position I get zilch.. no spark. The meter shows the battery putting out 11.87 volts. The key switch seems to be getting the power. Turning the key switch to the start position seemed to put out less than the the 11 plus volts. Im sorry it wash really turf to do this without another set of hands to turn the key while holding the probes. After disconnecting the pos bat term n switching to ohms. I only found the one safety switch pictured. It seemed to read 0 on the ohm meter. The meterhas an audible beep as well. The switch did beep indicating a complete circuit.. does that sound correct or do I sound like a complete bonehead?
Ok. Where do I go from here .. to the bar?? :drinkbuddies:
Hope this works I have no way to preview this before I send if it even makes it through. Service is sketchy up here.