YM1401D 3ph goes up ok=down no go

GrenAkrsFrmr · Nov 13, 2004

I have a Yanmar 1401D about 1980 mod, been very good tractor until one day I raised the 3ph which worked ok, but this time it just refuses to lower, still goes up(higher & higher), just not down, not even standing on lift arms.
HELP!!
I read some /forums/images/graemlins/confused.gifpost where others have had 3ph problems & I would like to get as much info as I can B4 tearing into the hydro control giz-mo. I don't know what all of the knobs, leavers, dip stick, and the little screw thing is that has a T type handle under the seat, are. I dont have a manual and some of the post talked about 'clearences'. I thought maybe something got stuck so I tapped around on things under the seat with a hammer, not real hard, but still no luck.
I hope I didn't mess something up when I had a bright ideal about using the 3ph to move a goat shed (idea didnt work, but if I ever need to remove the front tires, that does real good.) But the 3ph worked good after that, so I dont think that was it.
I also replaced the seat with one of those fishing boat swivel seats(a whole lot more comfortable) except when I turn arround to look back, the seat catches the lift control handle and lowers my 3ph, but dont really think that is the cause of my problem.
So, can somebody Please Help. Give me some ideas to try, or as a last resort, percautions about actually taking the control giz-mo apart?
Thanks so much, any advice is so much welcomed.

mark777 · Nov 13, 2004

Should be a round knob under the front part of your seat that will lock up your implement in the UP position. Rotate knob counter-clockwise (opening the valve) to unlock.

There is also a roll pin handle on the left (as you sit) under the seat that controls the fall rate of the lift arms. This will adjust the speed of the lift arms lowering implements to ground level.

For some reason kids love to play with these controls.

The only other thing that I can think of is perhaps the seat may interfere with mechanical linkage that actuates the lift arm assembly. Also a good penetrating oil sprayed on the controls will usually free up stuck valves.

Good luck, Mark

normde2001 · Nov 13, 2004

"and the little screw thing is that has a T type handle under the seat,"

Try that in both directions, one way holds up the 3ph. also make sure the round knob thingy down by your feet is open (CCW). That locks up the 3ph for servicing.

GrenAkrsFrmr · Nov 17, 2004

I would like to THANK everyone that took time to read my post, and especially those that entered suggestions of help. But alas, nothing seemed to have worked. I now have a manual on order, still have not physically taken the control thingy apart(will wait till recv. manual), but I did post some photos and would like everyone to take a look-see. They show my seat, & various other shots of the control thingy for the 3ph. Also in the return hydraulic line down by the right foot brake lock, it shows a section of rubber hose that has been inserted in the line, is this where that valve is suppose to be that locks the 3ph in the up position for servicing??
Thanks again folks, and if any new suggestions or precausitions please let me know B4 it is to late. Especially if someone has actually taken one of these control thingys apart B4. /forums/images/graemlins/confused.gif

gbirky · Nov 17, 2004

I took a look at your photos. One of them (titled Front right 3ph Control Thingy) shows a "T" handle which sticks forward under the seat. I am not familiar with the 1401, but most Yanmars have two of those. The one facing forward (the one in your picture) is normally used to lock the 3pt in the up position for servicing an implement. It is possible that it got turned in and locked the 3pt. Try turning it counter-clockwise, and see if the 3pt will lower. It may take several turns.

The other "T" handle normally is on the right side of the "3ph Control Thingy", and is used to adjust the rate at which the 3ph goes up and down. That one can also cause the same problem if it is turned all the way in.

It is also possible that you got some dirt in one of those
adjusters, and it won't allow hydraulic fluid to pass. You may have to dis-assemble the works to figure out what is wrong.

mark777 · Nov 17, 2004

GrenAkrsFrmr,

I have looked at all the photos and see your implement ( T Handle) lock down where it is supposed to be. It should turn freely CW and CCW. If not it is fairly simple to remove the valve assembly and disassemble in a small vice, clean with 1000 grit wet/dry quality abrasive paper, as they tend to have surface rust. Clean with carb and choke spray (or diesel) replace O ring and reassemble.

There is no photo of your flow-rate valve. It is about 12" to 14" back on the left side (as operator sits) with a roll pin sticking up and looks like an "L". Some are enameled in red.
It may be the roll pin handle is broken off or missing, and what is left appears to be a stud or 3/8 shaft and nut.

Once you find that valve, you will be able to remove and repair the same way as the implement lock down valve in the front. The flow rate valve has a detent spring and ball with an O ring. Free up, clean and reassemble, as I am fairly confident that one of the two valves will cure your problem.

BTW I am doing this from memory as I don't have my 1401 near by. Many of the YM models are set up the same way.

Good luck, Mark

normde2001 · Nov 17, 2004

"T type handle under the seat," If that is the handle in the pic behind this shifter, that probably takes the place of the round knob on that model, as that is where it is normally located. There should be another one similar to that, literally under the seat, ( you have to lift the seat to see it.

sourmash2 · Nov 29, 2004

I have a 2420D which developed the same problem. I have owned and used this tractor for almost 3 years, and this was the first trouble it has given me. I know this is a larger tractor than what you are working on, but maybe this info can help.
I went through all the same checks that you seem to have already made, and then I took my manual and started "operating". I had to take the side case off to get to the implement control valve and remove the control valve. I took the valve to a local hydraulic shop, and they found a small piece of trash lodged in one of the ports which was keeping the "unload valve" from working properly. It cost me $40.00, and my time to disassemble and re-assemble. All said, it wasn't a bad job. The manual helped alot, pictures are good!! /forums/images/graemlins/smile.gif
Hope this helps, good luck.

GrenAkrsFrmr · Dec 19, 2004

Yes, I'm at that point now. I have removed the fender and took out the 'T' spicket valve that is on the right hand side of the control thingy that adjust the drop rate= still no go down. I have ordered & received a parts manual that show exploded view of control thingy, and I am at the point where it looks like I am going to have to take the control thingy off of the tractor to get a view of it's insides working from underneeth. Question?? has any one taken the high pressure connection apart between the high pressure line and the control thingy. I will have to take this apart at that point in order to get my control thingy off of the tractor. Looks like there are 2 wrench type places between the control thingy and the high pressure line. Can I just use 2 wrenches to seperate the line at this point?? or is there something else I need to consider??
THANKS /forums/images/graemlins/confused.gif

bruce1966us · Dec 19, 2004

I have seen rust build up in the 3 pt lift cylinder that would not allow the 3pt to drop. The hydraulic pressure would still raise the lift, but of course there is no hydraulic down pressure. You can remove the housing that the threaded control valve screws into and visually inspect the cylinder. I think there are only 4 bolts.

Thanks,
Bruce