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1989 LT40 hydraulic Valve and Switch

Started by Chiselbut, May 08, 2024, 02:50:44 AM

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Hydraulic toe boards not functioning.

Insulation on smaller gauge wires at battery terminals started to melt. 

Lever actuated switch for this function does not appear to be working. No vibration or sound like the other three switches when they are pumping fluid.

Could it be that the melting wires and the hydraulic switch/valve issues are related? How and why?

My plan (let me know if this makes sense) is to disconnect battery and follow the wires, check for clean and good grounds, loose wires and bad connections from the battery to the hydraulic pump and motor. 

Replace wires, tighten and clean connections, check fuses and somehow test that switch (?)

Outside of calling WM - what advice and tips can you give me?

I appreciate the help here.  I'm a first time owner of a WM mill and it feels like i am learning the hard way - without prior experience and local support to draw from. 

Thoughts and thanks.



Wire heat like that is usually a sign of a loose connection, so you are on the right path. I would be checking for corrosion at all connections and inside of any crimp terminals.    The copper strip is the long, 1" tall piece on the operator side of the frame by the hydraulic box.  You also want to check the ground rub on the bottom rail to make sure you have a good, clean connection there.  
Franklin buncher and skidder
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Woodmizer LT Super 70 and LT35 sawmill, KD250 kiln, BMS 250 sharpener and setter
Riehl Edger
Woodmaster 725 and 4000 planner and moulder
Enough cows to ensure there is no spare time.
White Oak Meadows


Thanks.  Next:  hydraulic switch for the toe board.  They are 35 years old.  Hopefully WM still has the part.  


The simplest place to start when one hydraulic function stops is the micro switch on the valve.   The switches get out of adjustment sometimes.   

It takes longer to open the hydraulic box than adjust the switch.
Woodmizer LT50, WM BMS 250, WM BMT 250, Kubota MX5100, IH McCormick Farmall 140, Husqvarna 372XP, Husqvarna 455 Rancher


The 89 WM had different  valves than newer models. No micros. Four valves  hooked in sequence  to the common  manifold. Internal electrical parts still available. Replace the valve centering spring while  the handle  is off.


This is good information and pointing me in the right direction. will contact WM and see if i can get the parts.  Thank you. 


Here is a picture of the earlier 87-91 hydraulic switch.


The goods news is the toeboard valve  is the first in the line of valves.  The one you're focused  on in Pic. There is a small "0" ring where it sits on the manifold when going  back on. The solenoid  in the picture may need replacement  soon so get two so one on the shelf. 


I learn something new here everyday!  
Woodmizer LT50, WM BMS 250, WM BMT 250, Kubota MX5100, IH McCormick Farmall 140, Husqvarna 372XP, Husqvarna 455 Rancher


Woodmizer solenoid, hyd. motor. 
Part # P09595.
Don't  bother buying local. Several variations. 


As Sawyer Ted mentioned in your other post, register  mill with WM. Parts and over the phone help become fairly easy. 


I suppose, when i remove the switch and disconnect the lines: fluid will drain.

Advice needed:  if there is a hydraulic system drain is it best to just drain the system first?  Knowing that i also have cylinder leak that needs new seals, and i will be removing toe boards and the log lift for repainting.

In addition the wiring needs rebuilding so i may just pull the entire hydraulic pump and switch assembly/manifold too and rewire the system.

Thoughts ?


No need to drain fluid when disconnecting the toe board  valve. You're  above the reservoir.  Will be some fluid at hose disconnect area. Shop rag needed. 


I'm posting this progress to help another early LT40 owner.

Worked with a very patient and skilled technician (Doug) at Wood Mizer over the phone about this early hydraulic switch issue.  A+ experience. (He was working at WM during this early period and knows these early mills inside and out).

A complete switch is available and requires ordering from the manufacturer (Bucher). Price comes in at $361.89.  The internal spring is more likely the culprit and costs about $11.00.  A 100 uf 25v capacitor can be purchased at an electronics store.  The switch available is for the other 3 switches but are not exactly the same for the first in line toe board switch that has a slightly different design. He is consulting with others to determine if the switch plumbing can be modified to fit.

I ordered 3 springs (just in case).  He cautioned that the task to replace the spring requires care and many have damaged the switch or broke a fragile internal part while trying to fix the switch (perhaps a thin aluminum strip).  Yet, he said a person with basic mechanical skills and tools have successfully replaced the spring and repaired the switch too. He indicated that even their field repair techs have also had mixed results.

I will give it a try - and need to be in the right frame of mind when doing this.  Its easy for me to feel a little anxious and impatient when doing something for the first time.  Patience is a virtue. 

Let me know if this thread is helpful and i will take a few sequential photos of this repair and post them for the record.  I am guessing that these early first generation mills are nearing or at the point of needing these types of repairs (and there is not a lot of detail on the internet or You Tube about these early mills). 


Definitely  would be helpful for me to follow  along on this. Pics always  helpful.  Had no idea the toeboard valve was slightly  different  than the other 3 other than the pressure  release being plumbed into it.

Ben Cut-wright

The lever springs for the other valves require the entire valve be removed.  If those valves haven't been removed you may find the line nut below the valves frozen-stuck tight.  I've had to cut/bust these nuts and replace them when they would not turn.  Might be wise to have those on hand if yours are frozen or rounded off. 

The spring in the electrical contact section requires the valve be removed. So when replacing either the lever spring or the contact springs the valve will need to be removed. 

Parts manual calls out a different valve for the toe boards as you said.  Some revisions used "three way" valves and some used "four way". 

If you intend to remove all the valves to replace springs it might be wise to have at least one complete electrical kit on hand just in case there was damage to that component.  You might check the capacitors while you are in there.


I love discussing problems with Doug.  I always try to get him on the phone, when I have a problem or question. 
Mahindra 6520 4WD with loader/backhoe and a Caterpiller E70 Excavator.  My mill is a Woodmizer LT40HD Wide 35hp Yanmar Diesel. An old Lull 644D-34 called Bull


Good day.  The end result - the toe board switch was missing the contact spring.  The capacitor (or diode?) was also shorted or did not test as a functioning diode with the multi-meter. 

I ordered P09593 electrical repair kit from WM about $67.00 shipped. 

Side note:  the contact spring alone from WM is $11.00.  I found  a 100 uf 25v capacitor online for about $1.79.  I ordered several of these shipped for $8.66 and have 3 spare new contact springs from WM.  Making the capacitor assembly is done using 18 AWG wire, a crimped fork and round connector. Two 7/16 10-24 x 1/2 nylon screws at .41 (if needed at the  hardware store)  will yield you a repair fir less than $16.00. just FYI.  Another way to look at is:  4 valve/switch repairs can cost $270.00 or $68.00.

Tools: 3/4" open end wrench,  flat head screwdriver, 5/32 allen key, and 3/32 allen key for the small set screw holding the contact spring in place.

No need to remove the entire manifold assembly to do this repair.  I removed it to access bad connectors, frayed wires, and another switch that was leaking fluid from behind the front cap that soaked a folded paper towel under it in about 3 days.  Enough of a drip to annoy and to repair.

Fortunately the hex nut under the toe board valve was still good and not rounded over as the other valves were.  An almost 1/4 turn with a 3/4" open end wrench enabled removal of the cap and to check it out.

Don't go crazy wild bezerk and yank the cap.  The capacitor wire goes through a hole in the bottom of the cap.  Lift the cap just enough to access the capacitor screws.  Remove the two screws holding the capacitor assembly in place then completely remove the cap. 

Pictures show what the switch looks like under the cap, PO9593 kit, and a fresh painted assembly. 

The slow fluid leak came from a  7/16 - 24 threaded hole on the front of the valve.  Some aircraft thread sealant, small copper washer and a short bolt sealed this and two days later there is no drip.  At first i thought the lever shaft  O-ring was leaking.  No need to disassemble the valve from the back side.  Good to go for now until sawmill reassembly and testing at a later date. 

One last question:  i am not familiar with the type of plastic tube connector seen laying in front of the manifold in the photo.  Is this a compression fitting?  I pulled the tube out on the sawmill end - and I am wondering if i can push it back in for a sealed fit?  or do i need to find this connector?  What is the name for this connector? 


Here is a close up of the fitting in question

doc henderson

looks like a push-pull connector, Push the red part in towards the elbow, and the tube will come out.  push tubing in and when you pull on it the red part should come back out and grip it.  used in air and water connections often.
Timber king 2000, 277c track loader, PJ 32 foot gooseneck, 1976 F700 state dump truck, JD 850 tractor.  2007 Chevy 3500HD dually, home built log splitter 18 horse 28 gpm with 5 inch cylinder and 32 inch split range with conveyor powered by a 12 volt tarp motor

doc henderson

Timber king 2000, 277c track loader, PJ 32 foot gooseneck, 1976 F700 state dump truck, JD 850 tractor.  2007 Chevy 3500HD dually, home built log splitter 18 horse 28 gpm with 5 inch cylinder and 32 inch split range with conveyor powered by a 12 volt tarp motor


Photo shows contact spring, capacitor (inside cap (hard to see)two nylon screws, and copper contacts. Remember not to go cray wild bezerk if you need to remove the cap.  More than likely replacing the contact spring doesn't require removing the cap or the capacitor assembly. loosen the contact spring set screw inside the lever shaft and pull the spring.   

Conclusion:  for newbies not too familiar with hydraulic switches and valves and not able to find photo references on the internet - it would be easy to think this is going to overwhelm and shut the mill down.  I  had the impression parts were not available for a 35 year old mill.  As you can see - its not a big deal.  The complete toe board valve assembly however is NLA.  The other three valves are available (about $362.00).  I cant imagine these valves going bad - they are stout little hydraulic valves.  The wear items for the switch however, may need replacing ... judging by previous repair, missing parts and, rounded over base nuts, some cobbled wiring and lots of overspray paint from past disassembly efforts. 

Onto the next issue:  pulling and pressing out the main drive bearings, and inspecting the shaft.  Very rough bearing rotation: rusty dirt  water and little to no oil in the bearing assembly. 

doc henderson

the "frightprop" video is good.  used for pneumatic controlled Halloween stuff using pneumatic ram.
Timber king 2000, 277c track loader, PJ 32 foot gooseneck, 1976 F700 state dump truck, JD 850 tractor.  2007 Chevy 3500HD dually, home built log splitter 18 horse 28 gpm with 5 inch cylinder and 32 inch split range with conveyor powered by a 12 volt tarp motor

Ben Cut-wright

The component is a capacitor. It cannot be tested in the same manner as a diode.

Did you replace the lever springs?

Might be helpful to others to describe the process of loosening the hydraulic nut under the valve.

What was the "leaking" bolt hole that you fitted a screw into used for?

No idea what is causing the melted wiring?

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