Replacing Bobcat loader control valve seals

[willie59]

I have an update for the thread. Changed the control valve seals on a 753C recently, they're a kind of a PITA compared to the 763G and 773G. Because of the mounting location of the control valve, doesn't do any good to remove the machine side cover, it won't give you access to the control valve, everything has to be done from the topside. And the front of the control valve is a Bi-itch to get to because the loader arm manual descent valve body is in the way. Aside from this, the repair is pretty much the same method as other models, we'll just cover a few differences doing the 753C.

First, like with other models, remove the bucket, raise loader arms, install safety prop, and tilt bucket coupler all the way forward (dump). Make certain you have cleaned the dirt and crap in the belly of the machine under the control valve, you're going to need that hole open in the belly of the machine to drain oil into a pan when you pull control valve spools out.

The 753C had the hyd tank behind operators seat, you're going to have to drain the tank or you'll lose your oil when replacing control valve seals.



Best way to drain this tank? LoL, you guessed it, the suck bucket. Ha ha ha ha



Here's one of the problems you're going to have on this model, getting to the allen head screws that hold the dust boots and seal retainers on the front of the valve body, you can't get your hands in there for all the stuff in the way.



Now, removing the control valve to perform repairs would be a major disconnect deal, yuk! Likewise, removing that valve body for loader arm descent wouldn't be a piece of cake, no real good options here. Here's about the best you can get to access the front valve components.

Disconnect and remove this crossover pipe.



Remove the hose connected to the T fitting.

 

[willie59]

Remove the T fitting.



This gives you just a little access to the front of the valve. But don't get excited, it ain't much, you didn't just blow the world open. And if you have big fat hands, well, sorry, sucks to be you right about now. Prepare your list of favorite curse words. You can at least now get to the linkage pins and remove them with needle nose pliers, and you at least have enough access to use one hand to guide an allen wrench into the retainer screws.



There is a cavity on the opposite side of the descent valve body that you can get your other hand into to operate a 3/8 drive ratchet with an extension and an allen head driver socket on the end to remove the retainer screws. It's still a tedious operation as you really can't see what you're doing, this is pretty much done with your hands feeling their way through it.



Once you get the retainer screws out, you can remove the dust boots and seal retainer plates. Now it's time to go to the rear of the valve body.

Proceed by removing the spool end caps on rear of valve body, but be sure to remove the E clip on the lower spool end cap as mentioned in the last pic of post #3 of this thread.

If you simply attempt to remove the valve spools from the rear of valve body, they won't come out, the centering spring on the end of the spool will hit the fuel tank fill hose before they come out of the valve body. You have to remove the fuel hose where it's connected to the fuel tank, but you can't get to the hose clamp on the end of the fuel hose because the hyd pump output hose is in the way.



You have to disconnect the pump output hose from the pump, and tie it back with a zip tie. Now you can access the hose clamp on fuel hose. This is fun to work with this clamp where it's located.



That's pretty much the quirks of seal replacement on the 753C, the rest of the procedure is pretty much the same as with other models mentioned previously in this thread. One thing you don't have to mess with on the 753C is the spool locking solenoids on the front of the valve body as they don't use them. The 753C used the seat bar locking devices, so when you remove the linkage pins from the front of the valve spools, depress the plastic seat bar pad for the pedal locks with your hand and push the right pedal forward and the left pedal rearward, this will pull the linkage connections away from the valve spools so you can remove and re-install dust boots and seal retainer plates.

 

[cps]

Hi atco, I dont work on to many bobcats, or any skid steers, but i wana thank you for posting these threads in so much detail
it may well help me out someday!

Cheers Aiden

 

[willie59]

Hi atco, I dont work on to many bobcats, or any skid steers, but i wana thank you for posting these threads in so much detail
it may well help me out someday!

Cheers Aiden

Hello Aiden, well, to be sure, consider yourself one of the lucky mates. These little critters seem to have a way of finding me. :tong

 

[Soiled]

Atco could you pm me, I guess I spend to much time reading and not responding here and therefore don't have access to contact you..?
I'm an hour from Knox and have a repair you may/may not be interested in.

Thanks, Jeremy

 

[willie59]

Well Soiled, you just need one more post and you'll be able to private message any member, so post away.

Yep, you're not too far from me in Oneida. I can't send you a PM here until you become a Junior Member. I can send contact info to the email address you have provided on your profile. I'd be happy to hear if your problem is something I can help you out with.

 

[DrJim]

That fixes the spool valve seals, but what about the float detent?

I'm new to the forum, and was tickled to find your (Atco's) thorough instructions on servicing the spool valves. I'm lucky--I just happen to have a 773 G. But I'm not sure that leakage is a problem, rather the left pedal sticks--it sticks closed, requires excess foot pressure, and then pops open. The float function has never worked (never locked down). Is the sticking related to the float detent, or is the stickage possibly related to dirt or corrosion in the solenoid lockout device?

 

[willie59]

Welcome to the forum DrJim. You're not far from me with you in the atom city.

I can't say for sure, but your problem could be caused by the float detent parts, given you stated it doesn't work proper anyway. If it's been that way since you obtained the machine, maybe someone did something to the valve trying to repair it and messed up the detent, hard to say for sure. The only way to know for sure is pull the spool out on the loader arm section and check out the float detent components of the spool.

 

[DrJim]

When we found the machine in 2003 in the suburbs of Girdler, KY, it only had 162 hours on it. The float would sometimes lock down, but not often. I don't think anyone ever has had it apart. It has ? 750-800 hr on it, it's a 2001 model. The Bobcat folks say that the detent balls are steel, and they rust. (I don't know--maybe they are chromed and the plating wears off, and the balls get pitted.) But the Bobcat folks also act like you have to have a special tool to depress the spring. Maybe they are talking about trying to service the detent without pulling the spools apart? I figure my son and I can fix it, though it might make sense for us to bring it to you. How many rolls of hay is the job worth? We only have 20 left.

 

[willie59]

Well, it's kinda hard to guess just what's causing your problem. The machine sure doesn't have a lot of hours on it. If it were me, I think I would start pulling it apart and check the components because that machine has a lot of life left in it and I'd want things to work proper. You can't really take apart the float detent with the spool installed, the spool assembly needs to be removed from the valve body. And if I was going to do that, even though the machine has low hours, I'd replace the seals while I have it apart, which means I'd replace the seals on the bucket spool as well, get everything in good working order for a long time.

You're going to lose a little oil when you pull those spools out, so make sure you clean the well under the valve as best you can so oil can drain out the small hole at the rear of the well into a drain pan. Then start pulling the valve components apart as described in the thread inspecting parts as you go. You can check the operation of the spool lock solenoids when you get it removed from the valve body. Simply hold the lock assembly in your hand and have a helper hit the green enable button with the seat bar down, this will power up the solenoids and you can view the lock pin movement.

Once you get the loader arm spool out, then you can inspect float detent. I typically avoid pulling that device apart, but in your case, since it's not working proper, I think a pull apart is in order. Clean out a 5 gal oil bucket, hold the spool assembly down in the bucket vertically with the detent device at the bottom of the bucket. Pull the round sleeve on the end of the assembly away from the spool, you may have to pull it with a good snap. If the detent balls and spring are fitted proper, there's going to be two small steel balls fly out into the bucket, and possibly the spring as well, but at least you will have detained them inside the bucket instead of scattered across the shop.

Once you get it apart you can check for potential problems such as worn detent balls, wear grooves or notches, any thing that would affect detent or spool operation.

 

[bustedknuckle]

You can also wrap a rag around the detent sleeve and pull it off. That will catch the detent balls.

 

[DrJim]

You can also wrap a rag around the detent sleeve and pull it off. That will catch the detent balls.

Thanks for the support, bustedknuckle. I was thinking the same thing. With my luck, the darn parts would richochet out of the darn bucket that ATCO suggests. Maybe I'll use a rag _and_ the bucket. Considering what state he's in, ATCO ain't half bad.

 

[willie59]

Mostly...I'm in a state of confusion Jim. LoL

Get the detent apart however you want to. Getting it back together is the fun part.

 

[DrJim]

. . . Getting it back together is the fun part.

That's the secret that you haven't revealed yet . . . .

 

[1080 bobcat]

That's the secret just be ready to say a few good word's if don't have those specail pilers.

 

[DrJim]

That's the secret just be ready to say a few good word's if don't have those specail pilers.

With the spools out and the detent apart and cleaned, how long does it take to reassemble the detent parts if you _do_ have the special pliers? If it's only a minute--if the pliers save a lot of grief--it might be feasible for me to find someone with the pliers to do just that part. Or, ask ATCO what those special words are. . . .

 

[Sam_French]

Thank You Atco and all the other Bobcat/Skidsteer mechanics that have chimed in on this thread. I have learned a lot and own a 743B. What are knipex pliers?

Thank You

Sam French

 

[willie59]

With the spools out and the detent apart and cleaned, how long does it take to reassemble the detent parts if you _do_ have the special pliers? If it's only a minute--if the pliers save a lot of grief--it might be feasible for me to find someone with the pliers to do just that part. Or, ask ATCO what those special words are. . . .

Knipex makes a lot of different specialty pliers. They have one particular pliers that have an excellent tooth profile to work on the detent device. I typically just use ordinary tongue and groove pliers to compress the balls and spring, then slip the sleeve of the detent device onto the spool setting the detent balls inside. I wish I had some pics on servicing this item, but I don't, and it's hard to explain without pics. But you never know, there could be a Bobcat fall out of the sky on our lot tomorrow needing this done. Strange things like that happen.


Also, you're welcome Sam French.

 

[DrJim]

:bash

But you never know, there could be a Bobcat fall out of the sky on our lot tomorrow needing this done. Strange things like that happen. QUOTE]

That could be arranged faster than you think. Be careful what you wish for.

 

[willie59]

Well, it happens...T200 showed up yesterday. lol