753G grapple problem

[daytona701]

Hi, I resealed the cylinders on my Bobcat grapple recently. The grapple had sat unused for 2 years. Yesterday I went to use the grapple. At first I was able to open and close the claws, then the claws went full open and I couldn’t move close, then the tilt would only move down and the arms would raise and lower very slowly. The engine was straining against the pump. I don’t know if I have debris in the hydraulic system or a bad component. Any advice would be greatly appreciated.

 

[Tazza]

If you haven't used the aux hydraulics for a while, it soulds like one of your aux stems has gotten stuck
They can be opened up and cleaned, but they may be damaged doing so. WOrst case you need to find the one that is stuck and replace it.
If you remove the stems one at a time so you don't mix the parts up, remove the Orings and using soft jaws hold on to this oart of the stem, then use a spanner on the hex part and un-screw it. Remove the parts and note the order, ensure you get all the way down to the spool that is inside it, re-assemble with oil or WD40

 

[daytona701]

If you haven't used the aux hydraulics for a while, it soulds like one of your aux stems has gotten stuck
They can be opened up and cleaned, but they may be damaged doing so. WOrst case you need to find the one that is stuck and replace it.
If you remove the stems one at a time so you don't mix the parts up, remove the Orings and using soft jaws hold on to this oart of the stem, then use a spanner on the hex part and un-screw it. Remove the parts and note the order, ensure you get all the way down to the spool that is inside it, re-assemble with oil or WD40

Tarzan, where are the stems located on the machine. I traced the hydraulic lines to the hydraulic control box.

 

[daytona701]

Tarzan, where are the stems located on the machine. I traced the hydraulic lines to the hydraulic control box.

Auto correct did Tarzan instead of Tazza.

 

[daytona701]

If you haven't used the aux hydraulics for a while, it soulds like one of your aux stems has gotten stuck
They can be opened up and cleaned, but they may be damaged doing so. WOrst case you need to find the one that is stuck and replace it.
If you remove the stems one at a time so you don't mix the parts up, remove the Orings and using soft jaws hold on to this oart of the stem, then use a spanner on the hex part and un-screw it. Remove the parts and note the order, ensure you get all the way down to the spool that is inside it, re-assemble with oil or WD40

Tazza, I started the Bobcat this morning and the hydraulics started bogging down the motor immediately with no input on the controls by me. I have no experience working on hydraulics except resealing some leaking cylinders. I have the factory service manual on cd and looked over the hydraulic control valve. The Bobcat serial number is above 518811001 and I can see where the auxiliary hydraulic section is located in the valve. I bought the Bobcat used around 2009. Soon after the hydraulic control valve started leaking so I removed it and had the Bobcat dealer in New Orleans reseal the unit. It has worked well since. When I resealed the cylinders on the grapple I should have flushed the old fluid out before attaching the return line to my machine. I think I may have contaminated the system. The hydraulic fluid is due for a service. Do you think it would be a good idea to remove the control valve to reseal then flush the system to remove any crud? I also recently replaced the hose on the right drive side and at the same time chased down some codes that were thrown because of a loose ground at the battery negative terminal. I don’t believe these are related to the hydraulic problem.

 

[Tazza]

Tazza, I started the Bobcat this morning and the hydraulics started bogging down the motor immediately with no input on the controls by me. I have no experience working on hydraulics except resealing some leaking cylinders. I have the factory service manual on cd and looked over the hydraulic control valve. The Bobcat serial number is above 518811001 and I can see where the auxiliary hydraulic section is located in the valve. I bought the Bobcat used around 2009. Soon after the hydraulic control valve started leaking so I removed it and had the Bobcat dealer in New Orleans reseal the unit. It has worked well since. When I resealed the cylinders on the grapple I should have flushed the old fluid out before attaching the return line to my machine. I think I may have contaminated the system. The hydraulic fluid is due for a service. Do you think it would be a good idea to remove the control valve to reseal then flush the system to remove any crud? I also recently replaced the hose on the right drive side and at the same time chased down some codes that were thrown because of a loose ground at the battery negative terminal. I don’t believe these are related to the hydraulic problem.

I don't htink you have a contaminated system, that's what the filter is for, if everything else works as it should, i think it's ok.
The stems are on the top of the control valve, look for two coils with wires coming from them. The stem is the part that the coils sit on. They un-screw from the valve. When removing them, if the oil tank is still full, oil will pour out the hole, so i'd advise to drain all the oil you can before you start.
You can re-seal the valve with it still in the machine, you really don't want to pull the valve, all the tube lines connected to it are a nightmare to remove and re-install.

 

[daytona701]

I don't htink you have a contaminated system, that's what the filter is for, if everything else works as it should, i think it's ok.
The stems are on the top of the control valve, look for two coils with wires coming from them. The stem is the part that the coils sit on. They un-screw from the valve. When removing them, if the oil tank is still full, oil will pour out the hole, so i'd advise to drain all the oil you can before you start.
You can re-seal the valve with it still in the machine, you really don't want to pull the valve, all the tube lines connected to it are a nightmare to remove and re-install.

Tazza, drained hydraulic fluid, removed both coils on top of control valve, unscrewed both solenoid valves from the control valve. Is this the part you call stems? How do the coils work? Is the stem in the solenoid valve suppose to move up and down? The stems on the solenoid valve look to be one piece with the solenoid valve. What is the best place to get replacement o rings? I have two o ring kits from Harbor Freight but I don’t want to put crappy o rings in the machine. Sorry about the noob questions but that is how I learn.

 

[Tazza]

Tazza, drained hydraulic fluid, removed both coils on top of control valve, unscrewed both solenoid valves from the control valve. Is this the part you call stems? How do the coils work? Is the stem in the solenoid valve suppose to move up and down? The stems on the solenoid valve look to be one piece with the solenoid valve. What is the best place to get replacement o rings? I have two o ring kits from Harbor Freight but I don’t want to put crappy o rings in the machine. Sorry about the noob questions but that is how I learn.

Sorry for the late reply
Those are indeed the stems. Inside there will be parts that move when the coil is powered. They look to be one piece, but you can open them up.
New O rings and stems can be bought from Bobcat, but napa is a better option for orings.
If you turn the ignition on, activate the aux hydraulics and move the thumb switch, you should be able to feel the stem buzz in your hands with the coil on it. Ensure both do this, if one doesn't, it is probably bad. but try it on the other working coil if that' the case to ensure it is indeed different.

 

[buckwill]

Sorry for the late reply
Those are indeed the stems. Inside there will be parts that move when the coil is powered. They look to be one piece, but you can open them up.
New O rings and stems can be bought from Bobcat, but napa is a better option for orings.
If you turn the ignition on, activate the aux hydraulics and move the thumb switch, you should be able to feel the stem buzz in your hands with the coil on it. Ensure both do this, if one doesn't, it is probably bad. but try it on the other working coil if that' the case to ensure it is indeed different.

if when powering up does it bog down only when u engage the grapple or every time now, if it bos only when u engage then u have a problem with the engage valve not opening, possibled solenoid not opening, elect supply proble,. if it is trying to open and not succeeding then u have a stuck spool, put your hands on the hoses on each side of the cylinder, does the hose stiffen, if both the open and close side stiffen the you have 2 valves open essentially trying to engage both open and close the hydraulics, could be an open o ring or an electrical solemoid hanging open , this gives an identical result, this put power to both sides of the hydraulic system essentially pitting the hyd system against itself, cracck the fitting on each side of the appropiate cylinder during these test, if you have flow go to the spool supplying that cylinder, if this problems are in all cylinders, then look to the power beyond valves, brek your problem down to manageable pieces, its like the question, can u eat a whole ham, ?? the quick answer is heck NO!!, the country boy answer is ahh, yeah, let me get a loaf of bread, some mayonaise and some red koolaid, make sandwiches,, knowledge is power, u know your pump is working, find where the oil is trying to go, my guess is you have a stuck valve holding both sides of a valve open , or yoy have an electrical problem trying to engage both sides of a vaklve, since it did work, um also a bloown o ring essentially trying to engage both sides also, ok forgot, detritis getting into a spool holding it open resulting in both sides trying to service both sides of the system, sorry i do run on, ramble, buck, have fun, i think you have a contaminated iol supply