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Replacing Bobcat loader control valve seals

Joined
Aug 17, 2019
Messages
12
Location
waverly hall ga
Can i call u? hate to beg...not tonight but maybe tomorrow? ill be trying my seal job at 8:30 to 10:00am est tomorrow or you can try me 706-392-2580. thx
 
Last edited:
Joined
Aug 17, 2019
Messages
12
Location
waverly hall ga
I am giving up on this control block because of the aux valve history obvious crack in valve so im trying to get a good used one just to get to work faster. Do you know of the best sources for used parts? Any ideas are appreciated. Need immediately.
 

willie59

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Dec 21, 2008
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Knoxville TN
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Service Manager
I don't know of a source for used skid loader parts myself. Might be one out there, I'm just not aware of one.
 

crewchief888

Senior Member
Joined
Feb 1, 2012
Messages
1,781
Location
NWI
Willy, a lil history here. Bought a machine from water works atlanta that had very few hours but sat for 12 yrs because of a dead battery and flat tire. Alot of seals dry rotted so ive done wheel bearings and seals and all the cylinder seals. I tried doing control valve seals but kept getting leaks so i took the machine to a place locally called united rental equipment. I told them besides the control valve leaking that one side of the aux hydraulics had stopped working.

500 bucks and a week they said machine was ready and replaced all 4 spool seals again, so i picked it up so i took it to a time sensitive job and found it still leaking. 5 five gallon buckets in 2 weeks. I called united back when i lifted the cab and discovered the leak and all the aux solenoids werent connected at all PLUS THE ENTIRE AUX VALVE WAS LAYING IN BOTTOM OF MACHINE. I asked the mechanic what it was, he said aux valve but denied removing it. Had no idea how it got into belly of tractor. anyway, after that mess i tinkered with orings till i got it sealed and no leaks until last week when fluid started pouring from lower front corner of the control valve. Its the lower valve with detent in rear. When i pulled the lower valve out the rear, there were no seals in front of the control block, none period.
I slid in the valve from the rear and when in the control body i slid a green seal in front of body over the valve. Not sure if it went in backwards but after putting everything back together the machine still leaks profusely. The stream of oil is a dime size stream not just a drip. Any ideas what im doing wrong here. The green seal fits exactly inside the black rubber boot. machine is 753g with 700 hrs.

if you just put the front seal under the rubber boot, that's NOT where it goes....

your machine should have an aluminum plate that's under the front boot. it's called a seal retainer the seal goes UNDER that inside a counterbore t the front of the valve

:eek:
 
Joined
Aug 17, 2019
Messages
12
Location
waverly hall ga
if you just put the front seal under the rubber boot, that's NOT where it goes....

your machine should have an aluminum plate that's under the front boot. it's called a seal retainer the seal goes UNDER that inside a counterbore t the front of the valve

:eek:
Crew, do you know of any video or threads with pics so i can identify the aluminum plate retainer? Im desperate.
 
Joined
Aug 17, 2019
Messages
12
Location
waverly hall ga
Update: thx everyone, heres what i found. Pulled both boots off front of valve but never realized the locking solenoid cast iron block came off and with dirt around it looked like one piece so after separating the block from the valve it was simple. Ran it for 30 seconds till low oil shutdown stopped engine. Before it was gushing in 1 second so appears leak may be under control. It helps to look at a parts breakdown cause i swore that was one unit and didnt separate. Now anyone that needs help, call me as i can help even the slowest like me, lol. No skill needed to do these seals. Just the right tools which i can advise on. Thx to all who helped me here. Big chest bump. Love this forum.
 

willie59

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Dec 21, 2008
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Knoxville TN
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Service Manager
Don't know that I would consider myself a hero, just a guy with a lot of crap in my head. :D
 

willie59

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Dec 21, 2008
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Knoxville TN
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Service Manager
Willie, it all falls into the category of "I thought everyone knew that"........
And it never ceases to amaze me how many people don't know "that"

LoL, I suppose you're correct there Nige. I have worn so many hats in my lifetime about the only thing I haven't done is fly an airplane. I truly am a "jack of all trades and master of none". For the last two days I've spent most of my time in a Freightliner M2 tractor dragging trailers around. :D
 

Dave AWS

New Member
Joined
Aug 23, 2019
Messages
1
Location
Ohio
Don't know that I would consider myself a hero, just a guy with a lot of crap in my head. :D
Thanks from another new member. I just replaced the spool seals in my Bobcat 773G last night. I followed your list and it went very well. I'm a little dinged up bending myself around in the belly of the machine but feel very satisfied that I did this myself.
 

willie59

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Dec 21, 2008
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Knoxville TN
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Service Manager
I'm a little dinged up bending myself around in the belly of the machine but feel very satisfied that I did this myself.

LoL, I've always said working on the innards of a Bobcat is like working on top of a porcupine down in a hole. Good to hear you got it sorted out. :cool:
 

lawnguy

Member
Joined
Feb 9, 2020
Messages
22
Location
MidSouth
So after reading through a bunch of this I’m assuming the 743 control valve ( melroe single body) was a bit different than most?
Chasing a lift arm drop.
Had one cylinder packing bad.( repacked both sides)
One hardline between pump and motor bad ( replaced all)
Above work slowed it considerably but still does it.. however, every now and then when traveling it will stop for a second. I’m thinking trash in a spool but probably not my luck. Machine has zero leaks .
 

crewchief888

Senior Member
Joined
Feb 1, 2012
Messages
1,781
Location
NWI
So after reading through a bunch of this I’m assuming the 743 control valve ( melroe single body) was a bit different than most?
Chasing a lift arm drop.
Had one cylinder packing bad.( repacked both sides)
One hardline between pump and motor bad ( replaced all)
Above work slowed it considerably but still does it.. however, every now and then when traveling it will stop for a second. I’m thinking trash in a spool but probably not my luck. Machine has zero leaks .

there are 2 or 3 different control valves in the 40 series machines. spool seals are there to stop the valve/spool from leaking externally, has nothing to do with cylinder drift/drop. several things could be causing the problem. bad spot inside the cylinder barrel, cracked valve housing, broken centering spring on the lift spool, rust/corrosion in the lift detent assy, or the retainer bolt is loose on the detent.


:eek:
 

lawnguy

Member
Joined
Feb 9, 2020
Messages
22
Location
MidSouth
there are 2 or 3 different control valves in the 40 series machines. spool seals are there to stop the valve/spool from leaking externally, has nothing to do with cylinder drift/drop. several things could be causing the problem. bad spot inside the cylinder barrel, cracked valve housing, broken centering spring on the lift spool, rust/corrosion in the lift detent assy, or the retainer bolt is loose on the detent.


:eek:
I’ve worked on many older bc’s back in the day but that saying use it or lose it has kicked in.. that’s why I was asking about style of spools. I’m trying to locate the specific component repair manual for the that valve .. those seem to be rare .
 

lawnguy

Member
Joined
Feb 9, 2020
Messages
22
Location
MidSouth
AC979638-5AF3-41C7-BA75-6628C334ACAB.png AC979638-5AF3-41C7-BA75-6628C334ACAB.png So I’m down to the 4 parts circled.
It’s been many moons since I actually disassembled one of these. Is that spring not supposed to have more resistance than a ball point pen spring? I mean it is weak.
 

RBuchenan

New Member
Joined
May 19, 2020
Messages
1
Location
Massachusetts
An alternative method for repair is to remove the front drive lever panel, or whatever Bobcat
calls it, with the drive levers attached to it.

Disconnect the shock absorber dampeners from the front panel and flip them back out of the way.

Then disconnect drive links from cross shaft. The bolts go through threaded holes in drive links, the nut is a jam nut.


Hi Willie, at the risk of reviving a very old thread again. i am just starting this job on a 763C. is there any good reason NOT to break the two links at the junction in the middle and remove the whole front with the shock absorbers and front half of the links intact with the bellcranks?
 

willie59

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Dec 21, 2008
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13,361
Location
Knoxville TN
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Service Manager
Hi Willie, at the risk of reviving a very old thread again. i am just starting this job on a 763C. is there any good reason NOT to break the two links at the junction in the middle and remove the whole front with the shock absorbers and front half of the links intact with the bellcranks?

On some models it's easier to access the control valve components if you do that, it's not that hard to remove that panel and it opens things up nicely. Since you're doing a C series machine, might check that pivot bushing for the traverse bar that connects the left pedal to the control valve.
 

sid rust

New Member
Joined
Apr 12, 2017
Messages
1
Location
queensland australia
Thanks for a great thread willie59 and the other contributors. It was especially helpful with the seal orientation.
I was working on a 763g and the only things I can add is the traverse arm easily slides out through the r.h. side cover to get it out of the road.
The front panel is loosened and moved forward watch out for the pedal arm grommets when repositioning the panel. Thanks.
 
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