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Replacing Bobcat loader control valve seals

willie59

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Occasionally a member finds their Bobcat loader control valve making an oily mess of the bottom of their machine because it needs new seals for the control valve spools. Some simply take the machine to their local Bobcat dealer for repair, but others consider doing the repair themselves and save a little money, to which they ask if this is a job that they can do. If one has a bit of mechanical skills, it certainly is a project that can be done. Here are the basic steps to accomplish the repair. This was done on a 773 G Series loader. There may be differences on older models, such as a 743, but the differences have little affect on the procedures for doing this repair. On the wheel loaders, it's a little easier because you can remove a side plate to access the front of the control valve easy. On the track machines, such as T190, the track frame gets in the way of working through side panel so all parts of the repair are done on the topside with cab raised. Worst part about doing this repair is the stuff in the way of accessing the control valve components, but that just comes with working on a Bobcat, pretty much everything you need to work on with these machines has something in your way. Sorry about a few fuzzy pics, I had to get in a few awkward positions to take pics and it was hard to hold camera still while flash working. So, lets re-seal a control valve. If your working on a wheel machine, take the time to clean out the debris and gunk from underneath the drive motor on the control valve side by reaching through the removed side plate hole between wheels. At the rear of that compartment is a hole in the belly of the machine. Place an oil drain pan under the hole to contain the oil that will drain from control valve while making repairs. Track machines have the hole in a different location.

Bobcat control valve seals.jpg
 
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willie59

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Remove the linkage pins where the foot pedals links connect to the valve spools. Notice that rectangular link on the bottom spool, note it has two holes in the front of it where the traverse arm from the left pedal connects to it. Note which hole your traverse arm pin is in. Otherwise, when you reassemble the machine, you'll be scratching your head which hole it was in.

Bobcat control valve seals (1).jpg

Remove the bolt that connects the right foot pedal to the linkage arm. Pull the linkage arm forward toward front of machine.

Bobcat control valve seals (2).jpg

Remove the center pivot retainer bolt and washer from the traverse arm from left pedal, remove the two pivot mount nuts on each side of the center pivot, pull the traverse arm free and forward.

Bobcat control valve seals (3).jpg

Bobcat control valve seals (4).jpg

Bobcat control valve seals (5).jpg
 

willie59

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Now with the links pulled forward away from control valve you have need room to work on the control valve. Remove the four allen head bolts that secure the rubber spool dust boots and the spool lock assembly.

Bobcat control valve seals (7).jpg

Remove the rubber dust boots from the two spools. Now, with seat bar down, turn on ignition switch (or Run button if keypad control) but do not start engine. Push green Operate button at left control console. This will activate spool lock solenoids. Now simply slide spool lock assembly forward and off of valve spools. Once free of spools, turn ignition off. No need to disconnect wires, simply place lock assembly out of the way.

Bobcat control valve seals (8).jpg

Notice, for reassembly, that the coil on the end goes up, the backside of the lock assembly is smooth, and the front has a depression for the dust boots to
fit in.

Bobcat control valve seals (10).jpg

Slide the seal retainer disks foward and off the spools, and remove o-ring seals that sealed the mounting of spool lock assy to valve body.

Bobcat control valve seals (12).jpg

Now it's time work topside under raised cab on the backside of the valve body. You may have plastic seal caps on the spool centering spring caps. You can leave the plastic cap in place on top spool spring cap (green cap in pic below), but remove the bottom one to access the e-clip on the back of the lower spool cap. Very important, remove the e-clip and washer. If you don't, your likely to have 2 detent balls and a spring go to meet Alice in Wonderland in the belly of the machine when you remove the centering spring cap. Don't ask me how I know that.

Bobcat control valve seals (13).jpg
 
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willie59

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Remove the 2 allen head screws that secure the top spool cap and remove cap.

Bobcat control valve seals (14).jpg

Remove the 2 allen head screws that secure the lower spool cap. Grasp the cap and gently pull it off the detent mechanism. Make certaing that shaft sticking out the back of the cap is loose and free as your removing the cap. Do not put any pull on that shaft.

Bobcat control valve seals (18).jpg

Grasp the centering spring of the lower spool. Do not grasp or disturb the detent mechanism on the rear of the spool. Gently pull the entire spool assembly backwards out of the valve body.


Bobcat control valve seals (21).jpg

Remove the top spool assembly in same manner by grasping centering spring and pull entire spool out of valve body. Here are the two spool assemblies with old seals and seal retainer disks still on the spools.


Bobcat control valve seals (24).jpg

Now go back to front side of valve body and remove the old spool seals that are still in the valve body bores. Make sure there are no fragments of old seals left in the front or rear bores of valve body.

Bobcat control valve seals (23).jpg
 
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willie59

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Here's the 4 new spool seals and 2 o-rings to seal the spool lock assembly mounting.

Bobcat control valve seals (25).jpg

Notice the lip on the outer part of seal. The lip goes inward in the valve bores.

Bobcat control valve seals (26).jpg

Clean the valve spool with starting fluid or brake cleaner and compressed air to insure there's no dirt/grit on spool, place spools on a clean cloth while working with them. Lubricate the valve spool, then gently slip a new seal onto the spool, working it to the centering spring end of the spool. Take your time and be patient, being careful as your working the seal over the sharp edges along the spool.

Bobcat control valve seals (27).jpg

Here's the two spools with new seals fitted.

Bobcat control valve seals (28).jpg
 
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willie59

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Inspect the front and backside of the valve body to make sure there is no dirt/grit, clean if necessary. Make certain no dirt/grit gets in valve body bores or areas where seals go. Lubricate the lower spool with detent mechanism with assembly grease, place some grease where the seal will fit into valve body bore. Slide the spool into the lower valve bore until seal reaches valve body.

Bobcat control valve seals (29).jpg

Once seal encounters face of valve body, place fingers at rear of spool. Push the spool in with firm/steady finger pressure, the seal will pop into place in valve body. Perform same procedure for upper spool.

Bobcat control valve seals (30).jpg

Re-install the centering spring caps. Fit the washer and e-clip on detent device shaft. Re-fit plastic protector cap over e-clip.

Bobcat control valve seals (32).jpg

Bobcat control valve seals (33).jpg

Bobcat control valve seals (34).jpg
 
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willie59

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Go back to front of valve body, lubricate spools with assembly grease, gently fit new seals on spools. Make sure outer lip on seal goes inward toward valve body. Slip seal retainer disks on spools.

Bobcat control valve seals (36).jpg

Using steady finger pressure, press seal retainer disks inward to pop seal home in valve body.

Bobcat control valve seals (37).jpg

Apply a good amount of assembly grease to groove around outside perimeter of seal retainer disks on top and bottom spool. Fit your 2 new o-rings in the grooves around the seal retainer disks, pressing them fully into the grease in grooves. Smear the grease around the face of the o-rings. The grease will hold the o-rings in place during installation of spool lock assembly. (Sorry, my pic of o-rings installed was no good)


Bobcat control valve seals (38).jpg

Thoroughly clean the spool lock assembly with starting fluid or brake cleaner, dry with compressed air. Apply a film of assembly grease to the bores of the lock assy. Turn ignition on and press operate button to activate spool lock solenoids. Gently slide lock assy onto spools and home against valve body.

Bobcat control valve seals (39).jpg

Make certain you don't disturb seal lock assy after it's planted against valve body or you could upset one of the o-rings and get this. It appears whoever was in this valve before didn't properly set o-ring, this is what will result, tearing of the o-ring.

Bobcat control valve seals (42).jpg
 

willie59

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Apply some assembly grease to end of spools and spool lock assembly.

Bobcat control valve seals (40).jpg

Fit rubber dust boots onto spools. Replace boots if cracked or deteriorated. Install allen head mounting screws. Tighten each screw a little at a time to evenly set pressure on o-ring seals. Don't just lock one screw down and move to the next. Once allen head screws are set, turn iginition off.

Bobcat control valve seals (41).jpg

Rotate the top spool so the flats on spool are vertical, rotate the bottom spool so flats are horizontal. Go to front of cab, slide linkage bar backwards at right pedal, fit linkage to pedal with mounting bolt but do not tighten bolt yet.

Bobcat control valve seals (43).jpg

Re-install the traverse bar from left pedal onto pivot at center of traverse bar. Now you can re-install the link connections to spools. If your working on a track machine, this is the part that is an absolute PITA because it's difficult to get to these components from the top. You have my sympathy, use your own favorite swear words for the cuss fest. Once you have the links connected to the spools, now you can tighten the linkage mounting bolt on the right pedal.

Bobcat control valve seals (44).jpg

Well, we're done. You now have your new seals installed and are good to go. Don't forget to remove your drain pan from under machine. Somehow, Murphy's Law will insure you'll run over it and squash it.
 
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mljohn

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hey attco going to walts hitchen post for ribs tonight them fingers look as if they could use a good barbaq sause treatment
 

qball

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atco, i need a heart valve replaced, what do you charge?
 

alrman

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Awesome post ATCO ! :notworthy
Things a bit quiet at work? I mean, being able to document your job - hope the customer doesn't recognize his machine - he might want a discount !
Next time do you think you could use a hand model for those close up shots ! - Nice thumbnail :laugh:laugh
 

bill onthehill

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Atco, that is a great write up. The truth be told as we age we need to document things so when we have that vague remembrance of doing it before we can dig out the pics to jog our fuzzy thoughts! I have reached the age where I no longer stress myself by trying to work on BOBCATS! Retirement has the benefit of saying NO. I would offer to guide someone younger but the old joints don't contort like they used to.
 

AndyGrevis

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A good mechanic isn't expensive, he's priceless

Thanks Atco, fantastic write-up! :notworthy
 

willie59

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Awesome post ATCO ! :notworthy
Things a bit quiet at work? I mean, being able to document your job - hope the customer doesn't recognize his machine - he might want a discount !
Next time do you think you could use a hand model for those close up shots ! - Nice thumbnail :laugh:laugh

LoL! Yep, I keep the nails trimmed very short with nippers alrman. Got no use for fingernails myself, they're just another place on the hands to accumulate dirt/grease. Gotta be picky about my good looks ya know. :tong


Atco, that is a great write up. The truth be told as we age we need to document things so when we have that vague remembrance of doing it before we can dig out the pics to jog our fuzzy thoughts! I have reached the age where I no longer stress myself by trying to work on BOBCATS! Retirement has the benefit of saying NO. I would offer to guide someone younger but the old joints don't contort like they used to.

Yeah bill, they tend to be a bit more uncomfortable than in my younger years, but I'm not large of stature, still able to get in there and curse the little critters. I guess it's just my way of rebelling against old age. :cool:


Thanks Atco, fantastic write-up! :notworthy

Thanks Andy, just hoping it will assist some forum member. ;)
 

willie59

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what no chasing detent balls and springs down in there :cool2:pointhead


LoL...yeah, did that on the first 743 I did years ago...and out in the field. :Banghead Learned from the first experience with those detent balls and spring. :yup

Thanks for the reply bobcatmechanic, good to hear from ya. ;)
 

bobcatmechanic

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best thing i found for them is petroleum jelly and a pair of knipex pliers worth the money they want for them small pair awsome for control valve detents the biggest 22in pair great for cylinders
 

willie59

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best thing i found for them is petroleum jelly and a pair of knipex pliers worth the money they want for them small pair awsome for control valve detents the biggest 22in pair great for cylinders

By golly, it does look like the Knipex pliers would be perfect for that! I used a pair of tongue and groove pliers, but it looks like those would be the ticket. I'll have to look into that. Thanks for the advice. ;)
 
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